Advanced Liver Support [Discontinued] by Health Resources

POSSIBLY EFFECTIVE

• Dyspepsia. Oral artichoke leaf extract may improve symptoms in patients with functional dyspepsia or dyspepsia associated with biliary disease. Details: Several clinical trials in patients with functional dyspepsia or dyspepsia associated with biliary disease show that taking artichoke leaf extract can reduce symptoms such as nausea, vomiting, flatulence, and abdominal pain. Improvement seems to occur after 2 to 8 weeks of treatment (2056,11429,12208). The validity of some of this evidence is limited by a small sample size (2056) or lack of a control group (11429). However, a higher-quality clinical trial in patients with mild dyspepsia shows that taking artichoke leaf extract 640 mg three times daily for 6 weeks improves overall symptom and quality of life scores. Specifically, patient ratings for flatulence, feelings of fullness, and early satiety were reduced when compared with placebo. Further, for every 12 patients treated with this extract over placebo, one additional patient reported markedly or completely improved symptoms (12208). Some studies have used a specific extract called ALE LI 220 (Hepar-SL forte, Serturner Arzneimittel GmbH) at doses ranging from 320-640 mg three times daily for up to 8 weeks (2056,12208). Another study has used a different artichoke leaf extract (Cynara SL, Lichtwer Pharma) at a dose of 320-640 mg daily for 2 months (11429). Some clinical research has also assessed artichoke extract in combination with ginger extract. Results show that taking 2 capsules of a specific product containing artichoke leaf extract 100 mg and ginger extract 20 mg (ProDigest, Indena) daily for 4 weeks markedly or completely improves symptoms such as nausea, fullness, pain, and bloating in about 1.5-fold more patients with functional dyspepsia when compared with placebo (91474).
• Hyperlipidemia. Most research shows that oral artichoke lowers cholesterol and triglyceride levels in patients with hyperlipidemia. However, frozen artichoke juice does not appear to have these effects. Details: Multiple meta-analyses and clinical studies in patients who are either healthy or have hyperlipidemia, nonalcoholic fatty liver disease, or pre-obesity show that taking artichoke leaf extract or concentrated artichoke juice capsules daily for 4-24 weeks reduces total cholesterol by 13-18 mg/dL, low-density lipoprotein (LDL) cholesterol by 15-17 mg/dL, and triglycerides by 9-18 mg/dL, but does not increase high-density lipoprotein (HDL) cholesterol, when compared with placebo (104132,108713,111560,111564). While the five studies including non-hyperlipidemic patients in one of these analyses reported mixed results, all four of the studies evaluating artichoke leaf extract in patients with hyperlipidemia showed significant reductions in total cholesterol and LDL cholesterol when compared with placebo (104132). Additionally, a dose-response analysis suggests that baseline cholesterol levels are a stronger predictor of benefit than dose and treatment duration (108713). The validity of these findings is limited due to the high heterogeneity of studies included in meta-analyses. Another clinical study in patients with mild hypercholesterolemia shows that taking artichoke extract 250 mg twice daily for 8 weeks decreases LDL cholesterol by about 11% and increases HDL cholesterol by about 10% when compared with placebo (91478). Other formulations have also been evaluated, including cynarin, a constituent of artichoke, and artichoke juice. Some older, small clinical studies suggest that taking cynarin 20 mg three times daily for 2-7 months reduces total cholesterol and triglyceride levels when compared to baseline in patients with hypercholesterolemia and/or hypertriglyceridemia (52222,52223,52236). However, cynarin does not appear to reduce cholesterol levels in patients with familial type II hyperlipoproteinemia (1424). In patients with hyperlipidemia, consuming frozen artichoke juice 20-30 mL daily for 6-12 weeks does not appear to reduce total or LDL cholesterol levels and may even increase triglyceride levels (52216,52234). Artichoke leaf extract has also been evaluated in combination with other ingredients. Clinical research shows that taking a product containing red yeast rice extract, artichoke leaf extract, and other ingredients (Limicol, Laboratoire Lescuyer) 3 or 6 tablets daily for 4-16 weeks decreases LDL cholesterol by 14% to 21% in patients with hyperlipidemia. However, the red yeast in this product contains monacolin K (lovastatin), which likely contributed to the cholesterol-lowering effect (89451,89452,89454). Another specific product (Vazguard; Indena SpA), containing artichoke leaf extract (Indena SpA) 100 mg and bergamot phytosome 600 mg, has also shown benefit in patients with mild hypercholesterolemia when taken twice daily for 2 months (108712). However, it is unclear if this effect is due to artichoke leaf, bergamot, or the combination.

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Biliary disorders. Although there has been interest in using oral artichoke for various biliary disorders, including for the treatment of cholestasis or prevention of gallstones, there is insufficient reliable information about the clinical effects of artichoke for these conditions.
• Diabetes. Several small clinical studies suggest that oral artichoke extract may slightly reduce fasting blood glucose, but may not improve glycated hemoglobin (HbA1c) or other measures of glycemic control, in patients with diabetes. Details: A meta-analysis of 9 small clinical trials shows that taking artichoke leaf extract for 8-12 weeks reduces fasting blood glucose by around 5 mg/dL, but does not improve HbA1c, insulin levels, or markers of insulin resistance, when compared with placebo (105768). The generalizability of these findings to patients with diabetes is limited; only 2 of the 9 studies specifically enrolled patients with diabetes. The other studies included patients who were overweight or with liver disease, hyperlipidemia, or metabolic syndrome. In contrast, a post-hoc analysis of clinical research in overweight adults at risk for developing diabetes shows that taking a specific artichoke leaf product (Altilix, Bionap S.r.l.) 50 mg daily for 6 months reduces HbA1c by around 0.9% and improves measures of insulin resistance and beta-cell function when compared with placebo (111564).
• Hangover. It is unclear if oral artichoke extract is beneficial for the prevention of hangover. Details: A small clinical study in healthy adults shows that taking artichoke extract 960 mg immediately before and after alcohol consumption does not prevent alcohol-induced hangover when compared with placebo (11774).
• Hepatitis C. It is unclear if oral artichoke is beneficial in patients with hepatitis C. Details: One small clinical study in patients with chronic hepatitis C shows that taking artichoke leaf extract 3200 mg daily for 12 weeks does not normalize liver enzyme levels or reduce viral load when compared to baseline. Although symptoms such as fatigue, abdominal discomfort, and joint problems appear to improve in the first 4 weeks, the improvement is not maintained over 12 weeks (91475). However, another small clinical study shows that drinking a tea infusion of wild artichoke three times daily for 3 months normalizes liver enzymes and serum virus levels in 12 of 15 patients with hepatitis C (97717). The validity of these findings is limited by the lack of a control group.
• Hypertension. Analyses of small clinical studies suggest that oral artichoke may slightly reduce blood pressure in patients with hypertension; however, individual study results are conflicting, and the improvements in blood pressure may not be clinically significant. Details: Evidence regarding an association between artichoke consumption and hypertension is conflicting (91477,104133,105767,111561). Two meta-analyses include many of the same studies yet reach contradictory conclusions. One meta-analysis of 8 small clinical trials shows that taking artichoke leaf extract, powder, or juice for 8-12 weeks does not reduce systolic blood pressure (SBP) or diastolic blood pressure (DBP). However, subgroup analysis in patients with documented hypertension shows that artichoke reduces SBP by around 3 mmHg and DBP by around 2 mmHg when compared with placebo (105767). In contrast, another meta-analysis of 7 small clinical trials shows that taking artichoke 50-2700 mg daily for 4-12 weeks reduces SBP by about 2 mmHg and DBP by about 1.5 mmHg. Subgroup analysis shows that the greatest reductions in SBP and DBP occur in doses of 500 mg daily or less, at durations longer than 8 weeks, and in patients under 50 years old (111561). Discrepancies between the results of the meta-analyses with overlapping studies may be due to the former meta-analysis including artichoke supplementation in combination with other ingredients, while the latter meta-analysis focused on artichoke supplementation alone.
• Irritable bowel syndrome (IBS). It is unclear if oral artichoke leaf extract is beneficial in patients with IBS. Details: Some observational research in patients with IBS has found that taking a specific artichoke leaf extract (Hepar-SL forte, Serturner Arzneimittel GmbH) 640 mg three times daily for 6 weeks is associated with reductions in abdominal pain, cramping, bloating, flatulence, and constipation when compared to baseline (2562). Also, a small clinical study in patients with IBS shows that taking a different specific artichoke leaf extract (Cynara SL, Lichtwer Pharma) 320-640 mg daily for 2 months reduces the incidence of IBS symptoms in patients with dyspepsia by about 26% when compared to baseline. Patients taking this extract also had improved quality of life (15204). The validity of these findings is limited by the lack of a control group.
• Metabolic syndrome. It is unclear if oral artichoke leaf extract is beneficial in patients with metabolic syndrome. Details: A small clinical trial in patients with metabolic syndrome shows that taking artichoke leaf extract 1800 mg daily for 12 weeks does not improve fasting blood glucose, insulin resistance, total cholesterol, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, or blood pressure when compared with placebo. However, taking artichoke extract does reduce triglycerides by around 27 mg/dL when compared with placebo (100935).
• Nausea and vomiting. Although there has been interest in using oral artichoke for nausea and vomiting, there is insufficient reliable information about the clinical effects of artichoke for this purpose.
• Nonalcoholic fatty liver disease (NAFLD). It is unclear if oral artichoke leaf extract is beneficial in patients with NAFLD. Details: Meta-analyses of 12 clinical studies in adults with a variety of metabolic disorders, including NAFLD, show that taking artichoke 50-2700 mg daily for 4-24 weeks reduces alanine aminotransferase (ALT) and aspartate aminotransferase (AST) when compared with placebo (111560,111563). These effects are greater for ALT in trials lasting 8 weeks or longer and for AST at doses over 500 mg daily (111563). The validity of these findings is limited by significant heterogeneity among the included studies. A small clinical trial in patients with NAFLD shows that taking a specific artichoke leaf extract (Cynarol, Niak Pharmaceuticals), standardized to contain cynarin 2%, as 200 mg three times daily for 2 months improves NAFLD severity, reduces liver size, and increases hepatic vein flow when compared with placebo. The severity of NAFLD improved in 82% of patients taking artichoke, compared with 5% taking placebo. NAFLD severity did not worsen in any patients taking artichoke, compared with 27.5% of those taking placebo. Serum levels of liver transaminases, total bilirubin, and lipids were also improved with artichoke when compared with placebo (100934). However, the validity of these findings is limited by inappropriate randomization, the use of a per-protocol analysis, and significant differences between groups at baseline. Artichoke leaf extract has also been evaluated in combination with conventional therapies. A clinical trial shows that taking metformin 500 mg twice daily and/or vitamin E 400 IU once daily along with a specific artichoke leaf extract (Tishoke; Goldaru Company) 400 mg twice daily, providing 40 mg chlorogenic acid daily, for 12 weeks improves NAFLD severity and reduces liver size when compared with baseline. However, these improvements were similar to those seen in patients taking metformin with vitamin E. After 12 weeks, the number of patients with no fat accumulation (steatosis grade 0) increased by 23% in the artichoke and metformin group, 17% in the artichoke and vitamin E group, and 10% in the metformin and vitamin E group (108714)
• Obesity. A meta-analysis of several small clinical studies suggests that oral artichoke extract may slightly reduce waist circumference, but not body weight or body mass index (BMI), in patients who are overweight or obese. Details: A meta-analysis of 10 small clinical trials shows that taking artichoke leaf extract, powder, or juice for 8-12 weeks reduces waist circumference by 1.11 cm, but does not improve body weight or BMI, when compared with placebo (105766). The generalizability of these findings to patients who are overweight or obese is limited by the fact that only 3 of the 10 trials specifically enrolled patients because they were overweight. Other studies evaluated patients with liver disease, metabolic syndrome, diabetes, hyperlipidemia, or hypertension. In contrast, a post-hoc analysis of clinical research in adults with overweight shows that taking an artichoke leaf supplement (Altilix, Bionap S.r.l.) 150 mg daily for 6 months reduces body weight by around 2.3 kg but does not improve waist circumference when compared with placebo (111564).
• Osteoarthritis. Although there has been interest in using oral artichoke for osteoarthritis, there is insufficient reliable information about the clinical effects of artichoke for this purpose. More evidence is needed to rate artichoke for these uses.

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POSSIBLY EFFECTIVE

• Diabetes. Oral milk thistle extracts of silymarin seem to improve glycemic control in patients with diabetes. Details: A meta-analysis of 7 small heterogeneous clinical trials in patients with type 2 diabetes shows that taking milk thistle containing silymarin 210-600 mg alone or with other ingredients daily for up to 6 months reduces fasting blood glucose and glycated hemoglobin when compared with control. Sub-group analyses suggest that studies conducted for less than 3 months seem to have a greater glycemic benefit than those lasting 3 months or longer. Furthermore, there was a greater glycemic benefit when milk thistle was used in combination with other natural ingredients (105054). Most studies in the analysis used silymarin in divided doses of 420-600 mg daily, while only one study used 200 mg daily (15102,63190,97626,105054). Additionally, a meta-analysis of 22 clinical studies in healthy adults and adults with diabetes or other medical conditions shows that taking milk thistle reduces fasting blood glucose by around 22 mg/dL, reduces glycated hemoglobin by 0.85%, and reduces fasting insulin by 3.8 mU/mL when compared with placebo or control (113987). Most of these studies were conducted in the Middle East, so it is unclear whether these results are generalizable to other geographic locations. Most studies of combination products have been conducted in Italy and involve a specific product (Berberol, PharmExtracta) containing milk thistle standardized to silymarin 105-210 mg with tree turmeric standardized to berberine 500-1000 mg (96141,105054). In addition to improving glycemic indices in patients with type 2 diabetes (105054), this product has shown glycemic benefit in patients with concomitant obesity and metabolic syndrome (97624) and in patients with type 1 diabetes (96142).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Acne. It is unclear if oral or topical milk thistle is beneficial in patients with acne when used alone or in combination with other treatments. Details: A small clinical trial in patients with acne vulgaris shows that taking a milk thistle extract standardized to silymarin 140 mg daily for 2 months does not improve acne severity based on the Global Acne Grading system scale when compared with doxycycline 100 mg daily, and silymarin is less effective than doxycycline when evaluated using the Acne Severity Index (ASI) scale. In addition, using silymarin in combination with doxycycline does not appear to be more effective than doxycycline alone (101160). There is also interest in using milk thistle topically for acne. A small quasi-experimental study in adults with mild to moderate acne suggests that applying silymarin 1.4% cream twice daily for 3 months improves global acne scores and appearance of acne when compared to baseline, but not when compared with biweekly salicylic acid chemical peels (113143). However, the interpretation of these results is limited by the use of subjective outcomes. Similarly, observational research in patients aged 12-25 years with mild-to-moderate acne suggests that applying a specific cream (Cleanance Comedomed, Pierre Fabre Dermo-Cosmetique) containing milk thistle fruit extract 25% twice daily for 8-12 weeks as initial or add-on therapy is associated with moderate improvements in acne scores when compared to baseline (111175). The interpretation of these results is limited by the lack of a comparator group. Further, most patients were also prescribed other skincare products or treatments. Topical milk thistle has also been evaluated in combination with other ingredients. A small open-label study conducted in Korea in adults with acne vulgaris shows that applying a specific topical product (Silymarin CF, Skinceuticals) containing silymarin 0.5%, vitamin C 15%, salicylic acid 0.5% and ferulic acid 0.5%, twice daily for 3 months moderately improves acne scores when compared to baseline (110488). A similar open-label study conducted in Brazil in adults with acne shows that applying a serum with this same combination and concentration of ingredients once daily for 12 weeks improves investigator's global assessment of acne severity, global lesion count, inflammatory and non-inflammatory lesions, post-inflammatory hyperpigmentation, skin clarity, skin tone evenness, and overall skin appearance and reduces skin surface oil when compared to baseline. Additionally, an open-label study conducted in the US and Germany in adults with acne shows that applying this same serum daily for 4 weeks in addition to prescription topical acne medications reduces investigator-assessed erythema, dryness, and scaling when compared to baseline (113985). In the aforementioned studies, it is unclear if these effects are due to milk thistle, other ingredients, or the combination. The validity of the studies is also limited by the lack of a comparator group.
• Alcohol-related liver disease. It is unclear if oral milk thistle is beneficial in patients with alcohol-related liver disease, as evidence is conflicting. Details: Some preliminary research shows that taking a milk thistle extract containing 70% to 80% silymarin (Legalon, Madaus GmbH) 420 mg orally daily for one month to 4 years improves some liver function tests (2613,2618,17228,63260,63339). Some studies also report improvements in liver histology and survival (2616,17228,63278). However, in other studies, taking a similar dose of the same product for 3 months to 2 years is not associated with any benefit over placebo (7321,7322,7355,63158). A meta-analysis of clinical research also shows that milk thistle extract does not reduce mortality or complications related to liver disease in patients with alcohol-related liver disease (63192). Reasons for the conflicting findings are unclear but might relate to the low methodological quality of many of these studies.
• Allergic rhinitis (hay fever). It is unclear if oral milk thistle is beneficial in patients with allergic rhinitis. Details: One preliminary clinical trial shows that taking a milk thistle extract of silymarin 140 mg orally three times a day plus cetirizine (Zyrtec) 10 mg daily for one month decreases the severity of allergic rhinitis symptoms when compared with placebo plus cetirizine (18105).
• Alzheimer disease. It is unclear if oral milk thistle is beneficial in patients with Alzheimer disease. Details: A small, single-blind clinical study in patients with Alzheimer disease shows that taking milk thistle 450 mg daily for 3 months improves scores on the Mini Mental State Exam when compared with placebo (113978). Other preliminary clinical research shows that taking a supplement containing a milk thistle extract of silymarin 150 mg in combination with ferulic acid, gamma-oryzanol, and apigenin orally twice daily for 3 months to 2 years may stabilize mental functioning in patients with Alzheimer disease when compared to baseline (63223). It is unclear if this effect is due to milk thistle, other ingredients, or the combination.
• Amanita mushroom poisoning. While an intravenous milk thistle constituent, silibinin, has been studied for treating Amanita mushroom poisoning, this product is not readily available in the U.S. Details: Preliminary evidence from uncontrolled studies shows that administering silibinin, a constituent of milk thistle, intravenously (IV) within 48 hours of Amanita phalloides (death cap) mushroom poisoning, followed by oral therapy, may lessen liver damage (2615,63293). However, silibinin is not readily available in the US.
• Benign prostatic hyperplasia (BPH). Oral milk thistle has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research shows that taking a milk thistle extract of silymarin 190 mg along with selenium 80 mcg orally three times daily for 6 months may improve lower urinary tract symptoms, urinary flow rates, and residual volumes in adults aged 45-70 years with BPH when compared with placebo (88155). It is unclear if these effects are due to milk thistle, selenium, or the combination.
• Beta-thalassemia. Meta-analyses of clinical studies in patients with beta-thalassemia suggest that oral silymarin, a constituent of milk thistle, reduces serum ferritin levels. Details: Most small clinical studies and meta-analyses of these studies show that taking silymarin in conjunction with conventional iron chelation medications such as deferiprone, deferasirox, or deferoxamine, is more effective for reducing serum ferritin levels than taking a conventional medication alone (88154,98452,107375). In one meta-analysis, the combination of silymarin and deferasirox appeared to be more effective than combinations with other iron chelation medications (107375). However, one preliminary clinical study in patients 12 years of age and older with beta-thalassemia shows that taking a milk thistle extract containing 70% to 80% silymarin (Legalon, Madaus GmbH) 140 mg orally three times daily for 3 months, in conjunction with deferoxamine, does not improve serum ferritin when compared with deferoxamine alone (63212). This difference in outcome is likely due to the shorter duration of therapy. Silymarin also does not seem to affect total iron binding capacity or liver iron concentration in patients with beta-thalassemia (107375).
• Chemotherapy-induced acral erythema. It is unclear if topical milk thistle is beneficial in patients with acral erythema due to capecitabine. Details: Preliminary clinical research shows that applying a gel containing a milk thistle extract of silymarin 1% twice daily to the hands and feet, starting from the first day of chemotherapy and continuing for 9 weeks thereafter, prolongs the time to onset of acral erythema and decreases its severity when compared with placebo in patients with gastrointestinal cancer who are receiving capecitabine for the first time (95022).
• Chemotherapy-induced hepatotoxicity. Results of clinical studies are mixed over whether oral milk thistle prevents or improves chemotherapy-induced hepatotoxicity. Details: One small clinical study in children and adults up to age 21 with acute lymphoblastic leukemia (ALL) and elevated liver function tests (LFTs) shows that taking a specific product containing the milk thistle constituent silibinin (Siliphos, Thorne Research, Inc.) 80-320 mg (depending on patient weight) daily for 28 days concurrently with chemotherapy does not improve LFTs or bilirubin levels when compared with placebo (63218). Another small clinical study in patients with non-metastatic breast cancer receiving doxorubicin, cyclophosphamide, and paclitaxel shows that taking a specific milk thistle extract of silymarin (Livergol, Goldaru Pharmaceutical Company) 140 mg three times daily with meals for 4 weeks does not improve fatty liver grading or LFTs when compared with placebo (105795). Conversely, a large clinical study in children aged 5-14 with elevated liver enzymes and receiving chemotherapy for ALL shows that taking silymarin 70 mg capsules twice daily or 50 mg syrup three times daily for 9 months modestly improves aspartate aminotransferase (AST), alanine aminotransferase (ALT), and bilirubin levels, but does not improve alkaline phosphatase or albumin levels (113144). Similarly, observational research in patients with a variety of solid tumors and elevated LFTs due to chemotherapy or targeted therapy suggests that taking silymarin 150-900 mg daily is associated with reduced or stabilized LFTs in over half of patients; however, doses above 300-450 mg daily don't seem to have much more benefit (111176). The interpretation of these results is limited by the lack of a comparator group.
• Chemotherapy-induced nephrotoxicity. It is unclear if oral milk thistle is beneficial for the prevention of cisplatin-induced nephrotoxicity. Details: A small clinical study shows that taking a milk thistle extract standardized to 70% to 80% silymarin (Liverherb, Amin Pharmaceutical Company) 140 mg orally three times daily with meals, starting 24-48 hours before cisplatin and continuing until the end of three 21-day cycles, does not prevent cisplatin-induced nephrotoxicity when compared with placebo (95025).
• Chemotherapy-induced peripheral neuropathy. It is unclear if oral milk thistle is beneficial for chemotherapy-induced peripheral neuropathy. Details: A small clinical study in adults with cancer receiving cisplatin chemotherapy shows that taking a specific product (Livergol, Goldaru) containing milk thistle 140 mg three times daily for 3 months improves overall symptoms of chemotherapy-induced peripheral neuropathy when compared to baseline, but not when compared with placebo, with the possible exception of hyposthesia to touch and pins and needles sensation which had worsened only in the placebo group (113979).
• Cirrhosis. It is unclear if oral milk thistle extracts of silymarin are beneficial for cirrhosis from various causes. Details: Preliminary clinical research shows that taking a milk thistle extract of silymarin 420 mg orally daily for up to 4 years might improve liver function tests and decrease mortality in people with cirrhosis due to a variety of causes (2616,63145,63278,63340). However, a meta-analysis of clinical research evaluating milk thistle studies for the treatment of various liver diseases shows that effect sizes are generally small or lack statistical significance (63161). An observational study in adults with hepatitis B virus-related liver cirrhosis suggests that taking milk thistle 150 mg 2-3 times daily for at least 30 days in combination with anti-viral therapy is associated with lower mortality and liver transplantation rates at 1- and 2-year follow up and greater improvement in international normalized ratio, model for end-stage liver disease score, and the Charlson comorbidity index at 1-year follow-up when compared with anti-viral therapy alone (113986).
• Contrast induced nephropathy. It is unclear if oral milk thistle is beneficial for reducing the risk of nephropathy from contrast agents. Details: Population research in Taiwanese patients with liver cirrhosis has found that taking silymarin daily for at least 90 days during a one-year period does not reduce the risk of contrast-induced nephropathy during the following four or more years (98453).
• Coronavirus disease 2019 (COVID-19). It is unclear if oral milk thistle is beneficial for COVID-19. Details: Preliminary clinical research in adults hospitalized with COVID-19 requiring non-invasive oxygen support shows that taking a specific milk thistle product (SinaLive, Exir Nano Sina Company), 70 mg orally three times daily for 2 weeks, does not improve time to symptom resolution, lung scores, or length of stay when compared with placebo (109504).
• Critical illness (trauma). It is unclear if oral milk thistle is beneficial in critically ill patients with trauma-induced liver injury. Details: One small clinical study in patients admitted to the intensive care unit (ICU) due to trauma-induced liver injury shows that taking a specific milk thistle extract (Livergol, Goldaru Pharmaceutical Company) containing silymarin 140 mg three times daily for 14 days reduces markers of liver injury, including alanine aminotransferase (ALT) and aspartate aminotransferase (AST), when compared with placebo (105793). Whether this milk thistle extract improves morbidity, mortality, or length of ICU stay in these patients is unclear.
• Diabetic nephropathy. It is unclear if oral milk thistle is beneficial for improving kidney function in patients with this condition. Details: Preliminary clinical research in type 2 diabetic patients with diabetic nephropathy shows that taking a milk thistle extract of silymarin 140 mg orally three times daily for 3 months, in combination with conventional treatment decreases the urine albumin to creatinine ratio when compared with placebo. However, serum creatinine and estimated glomerular filtration rate are not improved (63250).
• Dyspepsia. Oral milk thistle has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A specific combination product containing milk thistle (Iberogast, Medical Futures, Inc.) seems to improve symptoms of dyspepsia. The combination includes milk thistle plus peppermint leaf, German chamomile, caraway, licorice, clown's mustard plant, celandine, angelica, and lemon balm (19532). A meta-analysis of clinical research using this combination product shows that taking 1 mL orally three times daily over a period of 4 weeks reduces severity of acid reflux, epigastric pain, cramping, nausea, and vomiting when compared with placebo (13089).
• Endometriosis. It is unclear if oral milk thistle is beneficial in patients with endometriosis. Details: Preliminary clinical research in females with ovarian endometrioma shows that taking a specific silymarin product (Goldaru Pharma) 140 mg twice daily for 12 weeks moderately improves pain scores, but not other sexual function scores, when compared with placebo (110486). However, some researchers have also recommended to avoid using milk thistle in estrogen-sensitive conditions, such as endometriosis, due to its estrogenic effects (93025,93026).
• Gambling disorder. It is unclear if oral milk thistle is beneficial for gambling disorder. Details: A small clinical study in adults with gambling disorder shows that taking milk thistle 150 mg twice daily for 2 weeks and then 300 mg daily for the next 6 weeks does not improve symptoms associated with gambling disorder, including gambling urges, thoughts, and behaviors, or improve symptoms of anxiety and depression when compared with placebo (113974). The interpretation of these results is limited by the small sample size and a strong placebo effect.
• Hepatitis. Small clinical studies suggest that oral milk thistle extracts of silymarin may improve hepatitis symptoms. It is unclear whether these products can improve liver function in these patients. Details: In people with hepatitis due to a variety of causes, taking a milk thistle extract containing 70% to 80% silymarin (Legalon, Madaus GmbH) 140 mg orally three times daily for 4 weeks reduces symptoms such as jaundice, dark urine, and scleral icterus, but does not improve liver function tests (LFTs) (63210,63317). However, some improvements in LFTs are seen with a silybin-phosphatidylcholine complex (Silipide, Inverni della Beffa Research and Development Laboratories) taken as 160-360 mg orally daily for 2 weeks to 3 months (63320,63321). However, there are methodological problems with these latter studies.
• Hepatitis B. Small clinical studies suggest that oral milk thistle extracts may improve liver function in people with hepatitis B, although it is unclear if these products can improve disease-related complications. Details: Preliminary clinical studies suggest that taking a milk thistle extract containing 70% to 80% silymarin (Legalon, Madaus GmbH) 140 mg orally three times daily for 28 days to one year, or a silybin-phosphatidylcholine complex (Silipide, Inverni della Beffa Research and Development Laboratories) 240 mg orally twice daily for 7 days, improves liver function tests (LFTs) and liver histology (7356,63263,63299). However, another study shows that taking a milk thistle extract of silymarin 140 mg orally three times daily for 5-25 days has no effect of LFTs (63288). A meta-analysis of clinical research and a review conclude that any clinical effect of milk thistle in people with viral hepatitis is very limited and results suggest that it lacks a significant effect on mortality, liver disease complications, or liver histology (17228,63192).
• Hepatitis C. Small clinical studies suggest that oral milk thistle extracts may improve liver function but do not seem to reduce hepatitis C virus (HCV) RNA levels. Details: Preliminary clinical studies show that taking a milk thistle extract containing 70% to 80% silymarin (Legalon, Madaus GmbH) 140 mg orally three times daily for 3-12 months, or a silybin-phosphatidylcholine complex (Silipide, Inverni della Beffa Research and Development Laboratories) 240 mg orally twice daily for 7 days, improves liver function tests (LFTs) and liver histology (7356,63299). However, other studies report that taking silymarin 125-140 mg three times daily for up to one year, 166 mg twice daily for 3 months, or 400 mg daily for 8 weeks does not improve serum HCV RNA levels, anti-HCV antibody levels, LFTs, or hepatomegaly (13170,63208,63247,63288,108658). Also, taking higher doses of silymarin, up to 700 mg three times daily for 6 months, does not have a significant effect on serum HCV RNA levels or LFTs when compared with placebo (63251). A meta-analysis of clinical research and a review conclude that any clinical effect of milk thistle in people with viral hepatitis is limited and most results show that milk thistle lacks a significant effect on mortality, liver disease complications, or liver histology (17228,63192,88156). Preliminary clinical research in adults with HCV-related advanced chronic liver disease shows that taking a specific milk thistle combination product containing silybinphospholipid complex 303 mg, vitamin D 10 mcg, and vitamin E 15 mg (Realsil 100 D, Ibi Lorenzini), twice daily for 12 months, improves liver stiffness scores, but not liver fibrosis scores, when compared with control (108659). It is unclear if this effect is due to milk thistle, other ingredients, or the combination.
• Hypercholesterolemia. Oral milk thistle has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A meta-analysis of three clinical trials in adults with hypercholesterolemia shows that taking a specific combination product (Berberol, PharmExtracta) containing milk thistle extract 105 mg and tree turmeric extract 588 mg twice daily for 3 months, along with diet and exercise, reduces levels of low-density lipoprotein (LDL) cholesterol by an average of 34 mg/dL when compared with diet and exercise alone. There was no effect on high-density lipoprotein (HDL) cholesterol or triglyceride levels (101158). The studies included in this meta-analysis are generally of low quality, lasted for no more than 12 months, and sometimes include patients with statin intolerance (95019,96140,101158). It is unclear if the effects of this product are due to milk thistle extract, tree turmeric extract, or the combination. Other clinical research shows that taking a similar product (Berberol K, PharmExtracta) containing milk thistle extract 105 mg, tree turmeric extract of berberine 500 mg, and monacolin K and KA 10 mg, taken once daily for 3 months along with diet and exercise, reduces levels of LDL cholesterol by about 28% when compared with diet and exercise alone in patients with hypercholesterolemia (97625). It is possible that any benefit of this product is due to the monacolin content.
• Hyperlipoproteinemia. It is unclear if oral milk thistle is beneficial in patients with hyperlipoproteinemia secondary to liver disease. Details: One very small crossover study shows that taking a milk thistle extract containing 70% to 80% silymarin (Legalon, Madaus GmbH) 420 mg orally daily for 7 months does not significantly improve cholesterol levels in patients with hyperlipoproteinemia secondary to liver disease when compared with placebo (63255).
• Hypoxic liver injury. It is unclear if oral milk thistle is beneficial for reducing liver injury in patients with hypoxia. Details: Preliminary clinical research in patients presenting to the emergency department with hypoxia shows that taking a milk thistle extract of silymarin 280 mg every 8 hours for 3 days reduces markers of liver injury, including alanine aminotransferase (ALT), aspartate aminotransferase (AST), and gamma-glutamyl transferase (GGT), when compared with placebo (103871).
• Infertility. It is unclear if oral milk thistle is beneficial for patients undergoing in vitro fertilization. Details: Preliminary clinical research shows that taking a milk thistle extract of silymarin 70 mg orally three times daily in combination with human chorionic gonadotropin (HCG) lowers the proportion of early and total apoptosis of follicle cells during in vitro fertilization due to male infertility. However, it does not have an effect on the number of oocytes retrieved or the thickness of the endometrium when compared with HCG plus placebo (63227).
• Lactation. It is unclear if oral milk thistle is beneficial for increasing milk production. Details: A small clinical study shows that taking a milk thistle extract standardized to 60% silymarin (BIO-C, Milte Italia S.r.l.) 240 mg twice daily for 4 weeks does not increase milk production when compared with placebo in mothers of preterm newborns (95027).
• Melasma. It is unclear if topical milk thistle is beneficial in patients with melasma. Details: Preliminary clinical research in adults with melasma shows that applying silymarin 1.4% cream twice daily for 3 months moderately improves melasma appearance scores when compared to baseline. These improvements were similar to hydroquinone cream 2% (110489). One small clinical trial in females with melasma shows that application of silymarin 1.4% cream twice daily to the affected area for 3 months is as effective for improving melasma area and severity as a specific type of laser therapy (low fluence Q switched ND:YAG 1064 nm) (105791).
• Menopausal symptoms. It is unclear if oral milk thistle reduces menopausal symptoms such as hot flashes. Details: One small clinical study in postmenopausal patients shows that taking milk thistle fruit extract 200 mg, containing 80% silymarin, twice daily for 8 weeks seems to reduce the number and severity of daily hot flashes and overall climacteric symptoms when compared with taking placebo (105053). This finding is limited by incomplete reporting and potentially inadequate blinding. Other preliminary clinical research has evaluated milk thistle in combination with black cohosh, dong quai, red clover, American ginseng, and chasteberry (Phyto-Female, SupHerb), with some evidence of benefit for reducing hot flashes and night sweats. (19552).
• Metabolic dysfunction-associated steatotic liver disease (MASLD). It is unclear if oral milk thistle is beneficial for MASLD. Details: A moderate-sized, open-label, non-controlled study in patients with MASLD shows that taking milk thistle standardized to silymarin 150 mg twice daily for 6 months does not improve liver stiffness or liver enzymes when compared with essential phospholipids. It is unclear if any changes in these outcomes are statistically significant when compared to baseline (114462). The validity of these findings is limited by the lack of a placebo group, lack of reporting of changes to diet and exercise, unclear statistical analysis and reporting, and the use of a per protocol analysis instead of intention-to-treat analysis. Also review milk thistle's effectiveness in nonalcoholic fatty liver disease (NAFLD), a similar condition.
• Metabolic syndrome. Oral silymarin, a constituent of milk thistle, seems to improve some of the laboratory abnormalities associated with metabolic syndrome. Details: A meta-analysis of 11 low-quality clinical trials in adults with metabolic syndrome, conducted in Asia and Africa, shows that silymarin, 140-2100 mg daily for 45 days to 12 months, modestly reduces fasting blood glucose, glycated hemoglobin, total cholesterol, triglyceride, and low-density lipoprotein cholesterol levels, and increases high-density lipoprotein cholesterol levels, when compared with placebo (107374).
• Multiple sclerosis (MS). Oral milk thistle has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in patients with MS shows that taking a supplement containing a milk thistle extract of silymarin 150 mg in combination with ferulic acid, gamma-oryzanol, and apigenin twice daily for 3-24 months may stabilize clinical symptoms of MS when compared to baseline (63223). It is unclear if this effect is due to milk thistle, other ingredients, or the combination.
• Nonalcoholic fatty liver disease (NAFLD). Small clinical studies suggest that oral milk thistle extracts of silymarin may slightly improve markers of liver function patients with NAFLD. Details: Four meta-analyses of up to 23 mostly small clinical trials in patients with NAFLD show that taking milk thistle products containing a total of silymarin 140-2100 mg daily, either alone or in combination with other ingredients, for 8-48 weeks reduces aspartate aminotransferase (AST) by 7-13 IU/L and alanine aminotransferase (ALT) by 9-17 IU/L when compared with control (97622,105051,113976,113982). However, these changes in liver enzymes may not be clinically impactful and some experts note that serum AST levels do not reliably reflect the spectrum of liver histology in patients with NAFLD (98130). Metabolic indices have also been evaluated. A meta-analysis of up to 20 mostly small clinical studies in patients with NAFLD shows that taking milk thistle for up to 48 weeks slightly improves serum lipids when compared with control (113976). A small clinical study in adults with NAFLD and a body-mass index (BMI) of at least 35 kg/m² shows that taking milk thistle extract 140 mg 4 times daily for 8 weeks, in addition to lifestyle modifications, reduces BMI by approximately 1 kg/m² when compared with placebo with lifestyle modifications (108657). However, another small clinical trial in adults with NAFLD and a BMI of at least 40 kg/m² shows that taking a specific silymarin product (Livergol, Goldaru Pharmaceuticals) 140 mg three times daily for 4 weeks did not reduce BMI or improve liver enzymes, such as AST and ALT, when compared with placebo (110484). A meta-analysis of 7 small clinical trials also shows there is little to no change in BMI associated with silymarin use in these patients (113976). One small clinical study in patients with NAFLD shows that taking a specific combination product (Eurosil 85, MEDAS SL) containing milk thistle extract standardized to silymarin 540 mg and vitamin E 36 mg daily for 3 months, in addition to following a low-calorie diet, does not appear to improve NAFLD-Fibrosis score or fatty liver index (FLI) when compared with following a low-calorie diet alone (96261), though a meta-analysis of 2 small clinical studies in patients with NAFLD shows that taking milk thistle for 12-24 weeks does reduce FLI when compared with control (113976). Also review milk thistle's effectiveness in metabolic dysfunction-associated steatotic liver disease (MASLD), a similar condition.
• Nonalcoholic steatohepatitis (NASH). It is unclear if oral milk thistle is beneficial in patients with NASH. Details: Clinical research in patients with NASH shows that taking a milk thistle extract of silymarin 700 mg three times daily for 48 weeks improves fibrosis in more patients when compared with placebo (96107). However, there is no significant between-group difference in global histological improvement with this product (96107) or with a specific silymarin product (Legalon, Rottapharm Madaus, Mylan) 420 or 700 mg three times daily for 48-50 weeks (101150). Pooling 1 of these clinical studies (96107) into a meta-analysis with another clinical trial that evaluated milk thistle in combination with phosphatidylcholine and vitamin E suggests an improvement in fibrosis by at least one stage when compared with placebo (113984). However, it is unclear if this effect is due to milk thistle, other ingredients, or the combination. Metabolic indices have also been evaluated. A meta-analysis of small clinical studies in patients with NASH or nonalcoholic fatty liver disease (NAFLD) shows that taking milk thistle reduces aspartate aminotransferase (AST) by about 13 IU/L, alanine aminotransferase (ALT) by about 17 IU/L, serum triglycerides by about 23 mg/dL and increases high-density lipoprotein cholesterol by about 2 mg/dL, but does not alter gamma-glutamyl transferase, total cholesterol, low-density lipoprotein cholesterol, body mass index, or insulin resistance when compared with control (113982). However, trials on NAFLD and NASH were not analyzed separately which limits the generalizability of these findings to patients with NASH specifically. The dose and duration of milk thistle treatment was also not described.
• Obesity. It is unclear if oral milk thistle is beneficial in patients with obesity. Details: A meta-analysis of 11 clinical studies in healthy adults and adults with various medical conditions shows that taking milk thistle does not reduce body weight or body mass index when compared with placebo or control (113987). A very small open-label study in adult females with obesity suggests that taking a specific milk thistle extract product (Neocholal-S, Italmex) 151.5 mg, containing silybin 45 mg, twice daily for 12 weeks does not reduce body weight but may reduce fasting blood glucose levels and insulin resistance when compared to baseline (113980). The validity of this study is limited by the lack of a comparator group and very small sample size.
• Obsessive-compulsive disorder (OCD). It is unclear if oral milk thistle is beneficial in patients with OCD. Details: Preliminary clinical research shows that taking milk thistle leaf extract 200 mg orally three times daily for 8 weeks has a limited effect on OCD symptom scores when compared to baseline, but does not provide any benefit over fluoxetine 10 mg three times daily (63219).
• Parkinson disease. Oral milk thistle has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research shows that taking a supplement containing a milk thistle extract of silymarin 150 mg in combination with ferulic acid, gamma-oryzanol, and apigenin orally twice daily for 3 months to 24 months may stabilize clinical symptoms in patients with Parkinson disease when compared to baseline (63223). It is unclear if this effect is due to milk thistle, other ingredients, or the combination.
• Postpartum complications. It is unclear if topical milk thistle is beneficial in postpartum patients with an episiotomy. Details: Preliminary clinical research in postpartum patients shows that applying milk thistle 3% in Eucerin ointment twice daily to the suture site for 10 days reduces episiotomy pain and improves the healing rate when compared with placebo. The milk thistle product was prepared with an ethanolic extract of the seeds to provide 1.53% silybin (107373).
• Prostate cancer. Oral milk thistle has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in patients with a history of prostate cancer who have had radiotherapy or radical prostatectomy shows that taking a dietary supplement containing a milk thistle extract of silymarin 160 mg, soy isoflavones (Novasoy, ADM) 62.5 mg, lycopene (Lyc-O-Mato, LycoRed Natural Products Industries, Ltd.) 15 mg, vitamins, minerals, and antioxidants orally daily for 10 weeks increases the time it takes for prostate-specific antigen (PSA) levels to double by 2.6-fold when compared with placebo (60361).
• Radiation dermatitis. It is unclear if topical milk thistle is beneficial in patients with dermatitis due to radiation. Details: Preliminary clinical research in females with breast cancer undergoing radiotherapy shows that applying a specific topical product containing a milk thistle extract of silymarin (Leviaderm, Madaus GmbH) significantly reduces the incidence of radiation dermatitis and prolongs the time to the onset of radiation dermatitis when compared with applying a panthenol-containing cream (63239). Additionally, meta-analysis pooling this study (63239) with one other small clinical study also shows that applying a cream or gel containing milk thistle extract reduces the incidence radiation dermatitis when compared with control (113674).
• Radiation mucositis. It is unclear if oral milk thistle is beneficial for preventing or treating mucositis due to radiation. Details: One small clinical study in patients with head and neck cancer receiving radiotherapy for the first time shows that taking a specific product containing a milk thistle extract of silymarin (Livergol, Goldaru Pharmaceutical Company), 140 mg three times daily starting from the first day of radiotherapy and continuing for 6 weeks thereafter, reduces the severity and prolongs the time to onset of radiation-induced mucositis when compared with placebo (95021).
• Toxin-induced liver damage. Most small clinical studies suggest that oral milk thistle extracts or constituents may reduce liver injury in people exposed to some, but not all, toxins and medications known to cause liver damage. Details: Taking a milk thistle extract containing 70% to 80% silymarin (Legalon, Madaus GmbH) 420 mg orally daily for up to one month improves liver function tests (LFTs) in people with abnormal LFTs due to chronic occupational exposure to paints or organic solvents such as toluene or xylene (2614,63280). Milk thistle extract has also shown some benefit for reducing drug-induced liver injury (DILI). In patients on isotretinoin therapy for acne, taking a specific milk thistle extract containing silymarin (Livergol, Goldaru Pharmaceutical Company) 140 mg daily for 30 days improves LFTs when compared with placebo (102852). A small clinical study in patients with relapsing-remitting multiple sclerosis who were initiating therapy with fingolimod shows that taking a specific milk thistle extract (Livergol, Goldaru Pharmaceutical Company) containing silymarin 140 mg daily for 6 months prevents fingolimod-induced LFT elevations when compared with placebo (105794). In patients receiving treatment for tuberculosis with rifampin, isoniazid, pyrazinamide, ethambutol, and streptomycin, taking the milk thistle constituent silibinin 70 mg orally three times daily for 6-12 months reduces the rate of liver toxicity to 14% compared with 53% in patients taking glucuronolactone 200 mg orally three times daily (63224). Additionally, in patients receiving standard treatment for tuberculosis with isoniazid, rifampicin, pyrazinamide, and ethambutol, taking a milk thistle extract of silymarin 140 mg orally three times daily for 4 weeks decreases the risk of DILI by 28% when compared with placebo. About 1 in every 4 patients who take silymarin for 4 weeks would avoid DILI (95024). A small clinical study in Iran, also in adults receiving standard treatment for tuberculosis, shows that taking a milk thistle extract of silymarin 150 mg twice daily for 2 weeks modestly improves LFTs when compared with control. None of the 16 patients in the silymarin group developed DILI compared with 2 of 21 patients in the control group; however, this finding was not statistically significant (112230). The interpretation of these findings is limited by the short study duration. However, taking a milk thistle extract of silymarin 420 mg orally daily for 3 months does not seem to prevent liver toxicity associated with tacrine (Cognex) therapy in people with Alzheimer disease (63140). Other research in people with elevated LFTs due to long-term therapy with phenothiazine or butyrophenone antipsychotic medications shows that taking silymarin 800 mg orally daily for 3 months also does not improve LFTs when compared with placebo (63344). A retrospective study in patients with DILI of various offending agents has also found that taking a milk thistle extract, containing a median of 450 mg silybin daily for 24 days is associated with 1.7-2.8 times higher likelihood of LFT normalization when compared with control (110485).
• Trichotillomania. It is unclear if oral milk thistle is beneficial in patients with this condition. Details: Preliminary clinical research in patients 12-65 years of age shows that taking milk thistle 150 mg twice daily for 2 weeks, and then 300 mg twice daily for 4 weeks, does not improve symptoms of trichotillomania when compared with placebo (99426).
• Ulcerative colitis. It is unclear if oral milk thistle is beneficial in patients with this condition. Details: Preliminary clinical research in patients 16-75 years of age shows that taking a specific milk thistle extract of silymarin (Livergol, Goldaru Pharmaceutical Company) 140 mg daily for 6 months, in conjunction with standard medications, decreases disease activity and helps maintain remission when compared with placebo in patients with ulcerative colitis (95029).
• Vitiligo. It is unclear if oral milk thistle reduces the severity of this condition. Details: Preliminary clinical research in a small number of patients with vitiligo shows that taking a specific milk thistle extract containing silymarin (Livergol, Goldaru Pharmaceutical Company) 140 mg twice daily along with phototherapy for 3 months does not improve the severity of vitiligo when compared with phototherapy plus placebo (102851). More evidence is needed to rate milk thistle for these uses.

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EFFECTIVE

• Acetaminophen poisoning. Oral and intravenous N-acetyl cysteine, as prescription drug products, are effective for treating acetaminophen poisoning. Details: Administering prescription N-acetyl cysteine orally or intravenously is effective in decreasing mortality rate and preventing the permanent sequelae of acetaminophen poisoning (17,64513,64745,64746). N-acetyl cysteine injection and oral effervescent tablets are approved by the US FDA for this use (102147,104164).
• Atelectasis. When inhaled, N-acetyl cysteine is effective for treating atelectasis. Details: N-acetyl cysteine solution for inhalation is effective for atelectasis caused by mucus obstruction (15,91650) and is approved by the US FDA for this use (102147).
• Bronchial diagnostic studies. When inhaled, N-acetyl cysteine is effective for bronchial diagnostic study preparation. Details: N-acetyl cysteine solution for inhalation is helpful when used to prepare people for bronchial diagnostic studies (15,91650), and is approved by the US FDA for this use (102147).
• Tracheostomy care. When inhaled and used as adjunct therapy, N-acetyl cysteine is effective for preventing endotracheal crusting in patients with a tracheostomy. Details: N-acetyl cysteine solution for inhalation is effective when used as an adjunct for preventing endotracheal crusting in tracheostomy care (15), and is approved by the US FDA for this use (102147).

POSSIBLY EFFECTIVE

• Angina. Oral or intravenous N-acetyl cysteine may reduce nitroglycerin tolerance in patients with angina. However, some studies suggest that N-acetyl cysteine might increase the risk for severe headaches and hypotension when used with intravenous or transdermal nitroglycerin. Details: Administering N-acetyl cysteine orally or intravenously, in combination with nitroglycerin, seems to improve unstable angina pectoris (2245,2246). There is also some clinical research showing that concurrent intravenous or oral administration of N-acetyl cysteine reduces the development of nitroglycerin tolerance (832,2245,64546). However, other research shows that taking N-acetyl cysteine orally does not reduce the development of nitroglycerin tolerance in angina patients (2281,2282). Additionally, severe headache and hypotension can occur when oral N-acetyl cysteine and nitroglycerin are administered together, which may limit the feasibility of concomitant use (2245).
• Autism spectrum disorder. Oral N-acetyl cysteine may improve irritability, but not other symptoms, associated with autism spectrum disorder. Details: One small clinical study in children with autism shows that taking N-acetyl cysteine 900 mg daily for 4 weeks followed by 900 mg twice daily for 4 weeks and then 900 mg three times daily for 4 weeks improves symptoms of irritability when compared with placebo (91241). Another small clinical study in children and adolescents with autism shows that taking N-acetyl cysteine 1200 mg daily plus risperidone for 8 weeks is more effective than risperidone alone for reducing irritability (91239). However, it does not seem to improve other symptoms, such as hyperactivity, social withdrawal, lethargy, repetitive behaviors, and inappropriate speech (91239,91241,97047).
• Bronchitis. Via inhalation, N-acetyl cysteine is FDA-approved for managing acute episodes of bronchitis. Oral N-acetyl cysteine may help to reduce the occurrence of acute exacerbations of chronic bronchitis when used for 3-36 months. Details: N-acetyl cysteine solution for inhalation is FDA-approved for the management of acute bronchopulmonary disease, including bronchitis (102147). Taking N-acetyl cysteine 1200-1500 mg daily orally for 4 months seems to reduce shortness of breath and coughing, and improve lung capacity, in patients with sulfur mustard-induced bronchitis (64586,64614). Also, taking N-acetyl cysteine orally, usually 400-600 mg daily, seems to reduce the risk of acute exacerbations of chronic bronchitis by a moderate amount when used for 3-36 months (6176,64419,102660). Symptom improvement has been shown to occur in 61% of patients taking N-acetyl cysteine, compared with 34% of those taking placebo (102660). However, oral N-acetyl cysteine does not seem to have a beneficial effect on chronic bronchitis when administered for shorter durations (64685,64696,64737,64818).
• Chronic obstructive pulmonary disease (COPD). Taking N-acetyl cysteine orally seems to decrease the exacerbation rate and improve symptoms in patients with moderate to severe COPD, particularly those who are not taking inhaled corticosteroids. Also, taking N-acetyl cysteine along with standard therapy appears to improve recovery in patients hospitalized due to an acute exacerbation. Details: N-acetyl cysteine solution for inhalation is FDA-approved for the management of chronic bronchopulmonary disease, such as COPD (102147). A meta-analysis of 12 clinical studies involving 2,691 patients shows that N-acetyl cysteine, given as 257-1800 mg daily for at least 6 months, decreases the number of patients experiencing at least one COPD exacerbation by 15% when compared with placebo; however, it is not associated with a reduction in COPD exacerbation rate or improvement in measures of lung function (97046). Some smaller studies have shown a higher improvement rate of 23% to 40%, with the greatest efficacy seen in patients who are not already taking inhaled corticosteroids (10429,64552). While some studies have failed to show any benefit of N-acetyl cysteine, the lack of benefit appears to correlate with a treatment duration of less than 6 months (64704,97039,97046). The 2015 guidelines from the American College of Chest Physicians and Canadian Thoracic Society (AECOPD) recommend that N-acetyl cysteine be considered as an adjunctive treatment option for patients with moderate to severe COPD and a history of 2 or more exacerbations in the previous 2 years (97043). The 2017 Global Initiative for Chronic Obstructive Lung Disease (GOLD) guideline also states that N-acetyl cysteine may be an appropriate treatment option for patients who are not able to use inhaled corticosteroids (97050). In hospitalized patients with an acute exacerbation of COPD, preliminary clinical research shows that adding N-acetyl cysteine 1200 mg daily to regular treatment has a moderate effect on wheeze and the need for oxygen over a 7-day period when compared with regular treatment alone (102653).
• Contrast induced nephropathy. Oral or intravenous administration of N-acetyl cysteine seems to prevent contrast induced nephropathy in patients with kidney dysfunction. However, it is not beneficial in those with normal kidney function or diabetes. Details: Large meta-analyses of over 150 clinical studies in patients with reduced kidney function (serum creatinine of 1.2-2.4 mg/dL) show that oral N-acetyl cysteine is more effective than either sodium bicarbonate or saline hydration alone in preventing contrast agent-induced kidney damage after coronary angiography, computed tomography, left heart catheterization, and/or percutaneous coronary intervention. N-acetyl cysteine in combination with sodium bicarbonate appears to have similar efficacy to N-acetyl cysteine monotherapy, with an odds ratio of 0.62-0.67, when compared with hydration alone. Pretreatment with high-dose statin, prostaglandin, or theophylline appears to be more effective than N-acetyl cysteine, with odds ratios of 0.37, 0.37, and 0.48, respectively, when compared with hydration alone. However, combination treatment with N-acetyl cysteine and a high-dose statin appears to provide the greatest benefit of all treatments studied, with an odds ratio of 0.31, when compared with hydration alone. No treatments demonstrate significant efficacy in reducing the risk of contrast induced nephropathy in patients with diabetes (97036,97038). Some evidence also suggests that N-acetyl cysteine may have similar effects to fenoldopam in reducing the risk of contrast induced nephropathy in patients with reduced kidney function (64489,97036,97038). N-acetyl cysteine does not reduce the risk of contrast induced nephropathy in patients with normal kidney function (mean serum creatinine less than 1.2 mg/dL) when compared with control (64538,64573,64617). Although many individual studies have failed to show a significant benefit (11430,64514,64543,64561,64581,64623,64639,91232,91236,106884), pooled evidence from these and many additional studies provide a benchmark for the place for N-acetyl cysteine in reducing the risk of contrast induced kidney damage in people with reduced kidney function.
• Hyperhomocysteinemia. Oral N-acetyl cysteine seems to reduce homocysteine levels. Details: Taking N-acetyl cysteine orally seems to reduce homocysteine levels in patients with elevated homocysteine levels, including those with kidney failure requiring dialysis (2258,64542,64596).
• Hyperlipidemia. Oral N-acetyl cysteine seems to reduce lipoprotein(a) levels. Details: Taking N-acetyl cysteine orally seems to modestly reduce lipoprotein(a) levels in patients with hyperlipidemia (2256,2257,64516).
• Ifosfamide (Ifex) toxicity. Oral N-acetyl cysteine may be beneficial for reducing ifosfamide toxicity, although it does not appear to be as effective as mesna. Details: Taking N-acetyl cysteine orally seems to reduce ifosfamide-induced bladder toxicity (5808,10270,64730). However, mesna seems to be more effective for preventing ifosfamide toxicity than N-acetyl cysteine (10748).
• Influenza. Oral N-acetyl cysteine may reduce the risk for symptomatic influenza. Details: One multi-center clinical trial conducted in Italy shows that taking N-acetyl cysteine 600 mg twice daily for 6 months does not prevent influenza infection, but reduces the risk for clinically apparent disease by 68%, when compared with placebo (2260).
• Kidney failure. Oral N-acetyl cysteine may reduce the risk for cardiovascular events in patients with kidney failure. Details: One clinical study in adults with kidney failure who have been on dialysis for at least 3 months shows that taking N-acetyl cysteine 600 mg twice daily reduces the incidence of cardiovascular events, such as ischemic stroke and myocardial infarction, by about 40% when compared with placebo. There was no effect on total mortality or mortality from cardiovascular causes, although the study may have been inadequately powered to detect a difference in these outcomes (10430).
• Myocardial infarction (MI). Intravenous N-acetyl cysteine, along with standard therapy, seems to improve outcomes in patients with MI. Oral N-acetyl cysteine has not been evaluated for this use. Details: Clinical research in adults undergoing percutaneous coronary intervention (PCI) for ST-segment elevation MI shows that administering N-acetyl cysteine with nitroglycerin as a continuous intravenous infusion for 48 hours reduces myocardial infarct size by 5.5%, doubles the extent of myocardial salvage, and shortens the time to chest pain resolution when compared with nitroglycerin plus placebo (97044). Additional preliminary clinical research shows that intravenous N-acetyl cysteine, when given with nitroglycerin and streptokinase in patients with evolving MI, may preserve left ventricular function and reduce oxidative stress (7872,64502,64778).

POSSIBLY INEFFECTIVE

• Amyotrophic lateral sclerosis (ALS, Lou Gehrig's disease). Subcutaneous administration of N-acetyl cysteine does not seem to improve survival or disease progression in patients with ALS. Details: One clinical trial in patients with ALS shows that administering N-acetyl cysteine 50 mg/kg daily for 12 months via subcutaneous injection does not improve survival or slow disease progression when compared with placebo (2254).
• Anthracycline cardiotoxicity. Oral N-acetyl cysteine does not seem to prevent or treat doxorubicin-induced cardiac toxicity. Details: Small clinical studies show that taking N-acetyl cysteine orally does not seem to prevent or reverse doxorubicin-induced cardiac toxicity when compared with placebo or a control group (2252,2253,64712).
• Bronchopulmonary dysplasia. Intratracheal N-acetyl cysteine does not seem to prevent bronchopulmonary dysplasia in premature infants. Details: Clinical research in premature infants shows that intratracheal N-acetyl cysteine does not seem to improve symptoms, hasten recovery of chronic lung disease, or reduce the risk of bronchopulmonary dysplasia when compared with placebo (64460,64490).
• Cannabis use disorder. Oral N-acetyl cysteine does not seem to improve abstinence rates in patients with cannabis use disorder. Details: Most clinical research in adolescents and adults with cannabis use disorder shows that taking N-acetyl cysteine 1200 mg twice daily for 8-12 weeks as an adjunct to counseling and other interventions does not reduce symptoms of depression or help with cannabis abstinence (99531,102663,102666,102668). Although a single study shows that taking N-acetyl cysteine more than doubles the odds of a negative urine cannabinoid test over an 8-week period in adolescents aged 15-21 when compared with placebo, there was no significant difference in the time to first negative urine cannabinoid test or end of treatment abstinence (102666).
• Cystic fibrosis. Oral or inhaled N-acetyl cysteine does not seem to improve lung function in patients with cystic fibrosis. Details: Most clinical research shows that taking oral or nebulized N-acetyl cysteine does not significantly improve lung function or lung capacity in patients with cystic fibrosis when compared with a control (22735,64406,64671,64743). However, one preliminary clinical study shows that high-dose oral N-acetyl cysteine reduces the number and activity of airway neutrophils in these patients when compared with placebo (64510).
• Erythropoietic protoporphyria (EPP). Oral N-acetyl cysteine does not seem to improve photosensitivity in patients with EPP. Details: Small clinical studies show that taking N-acetyl cysteine 1800 mg daily orally for 4 weeks does not improve photosensitivity in patients with EPP when compared with placebo or baseline (64448,64756).
• Helicobacter pylori. Adding oral N-acetyl cysteine to conventional Helicobacter pylori (H. pylori) eradication regimens does not seem to increase eradication rates. Details: Despite conflicting findings from individual, small clinical studies (64497,97042), meta-analyses of clinical research show that adding N-acetyl cysteine to a standard antibiotic eradication regimen does not improve eradication when compared with standard eradication therapy alone (99530,106901). N-acetyl cysteine has also been evaluated in combination with other ingredients. Preliminary clinical research shows that taking N-acetyl cysteine 600 mg orally twice daily in combination with curcumin 30 mg, bovine lactoferrin 100 mg, and pantoprazole 20 mg, all taken twice daily for one week, without antibiotic therapy does not eradicate H. pylori infection, although it might improve dyspeptic symptoms and gastrointestinal inflammation (64559).
• Hepatitis. Oral N-acetyl cysteine does not appear to improve treatment response in patients with hepatitis. However, when taken with interferon, it might lengthen the time to relapse. Details: Taking N-acetyl cysteine orally does not seem to benefit patients with acute viral hepatitis (64462). Also, adding N-acetyl cysteine to conventional interferon therapy does not seem to improve treatment response in patients with hepatitis C when compared with interferon therapy alone (64418,64799,64825). However, some clinical research shows that adding N-acetyl cysteine to interferon therapy delays relapse in hepatitis C patients when compared with interferon treatment alone (64424).
• HIV/AIDS. Oral N-acetyl cysteine does not seem to increase CD4+ cell count in patients with HIV. Details: Small clinical studies show that taking N-acetyl cysteine 400 mg orally twice daily or 600 mg once daily for 4-6 months does not improve CD4+ cell counts or viral load in patients with HIV when compared with placebo (64482,64779). In addition, taking N-acetyl cysteine 600 mg orally three times daily in combination with sodium selenite 500 mcg daily for up to 24 weeks does not affect the percentage of CD4+ lymphocytes or viral load in HIV patients when compared with a control (64798).
• Hypotension. Oral N-acetyl cysteine does not seem to improve renal outcomes in patients with prolonged hypotension. Details: One clinical trial in patients with prolonged hypotension shows that taking N-acetyl cysteine orally for 7 days does not reduce the risk of acute kidney failure when compared with placebo (64545).
• Infertility. Oral N-acetyl cysteine does not seem to improve fertility in females with unexplained infertility. Details: One clinical trial in females with unexplained infertility shows that taking oral N-acetyl cysteine 1200 mg daily in addition to clomiphene citrate 50 mg twice daily for 5 days, beginning on the second day of the cycle, does not improve pregnancy rate or reduce miscarriage rate when compared with clomiphene citrate alone (64528).
• Liver transplant. Intravenous N-acetyl cysteine during liver donor operation does not seem to improve liver transplant outcomes. Oral N-acetyl cysteine has not been evaluated for this use. Details: One clinical trial shows that administering N-acetyl cysteine intravenously during a liver donor operation and preserving the liver in cold solution containing N-acetyl cysteine does not reduce the risk of ischemia reperfusion injury or acute cellular rejection in liver transplant recipients when compared with control (64486).
• Pancreatitis. Oral N-acetyl cysteine does not seem to prevent pancreatitis after endoscopic retrograde cholangiopancreatography (ERCP). Additionally, intravenous N-acetyl cysteine does not seem to reduce the risk of organ dysfunction in patients being treated for severe acute pancreatitis. Details: Two clinical trials show that taking oral N-acetyl cysteine 1200 mg once before undergoing ERCP does not reduce the risk of post-ERCP pancreatitis when compared with placebo (64522,109939). One of these trials also evaluated oral N-acetyl cysteine in combination with rectal indomethacin, but the incidence of post-ERCP pancreatitis did not appear to be lower when compared with taking indomethacin alone. However, the study may have been inadequately powered to detect a difference between those groups (109939). In patients with severe acute pancreatitis, intravenous N-acetyl cysteine, in combination with selenium and vitamin C, also does not seem to reduce the risk of organ dysfunction (64551).
• Postoperative recovery. Oral or intravenous N-acetyl cysteine does not seem to improve survival, prevent complications, or reduce length of hospital stay in patients undergoing cardiac or liver surgery. Details: N-acetyl cysteine, taken orally or intravenously, does not seem to reduce the risk of myocardial infarction, stroke, kidney injury, or mortality or reduce the length of hospital stay following cardiac surgery (64610,64624,64628,64635,91233,91240). While some meta-analyses of clinical research show that taking N-acetyl cysteine orally or intravenously reduces the odds of postoperative atrial fibrillation by 36% to 44% when compared with placebo in patients undergoing cardiac surgery (64635,91233,91240), conflicting results exist (64624). In patients undergoing liver resection, intravenous N-acetyl cysteine does not reduce complication rate, risk of liver failure, length of hospital stay, or mortality when compared with a control group. In fact, patients receiving N-acetyl cysteine were more likely to experience delirium and its associated complications (99532).

LIKELY INEFFECTIVE

• Head and neck cancer. Oral N-acetyl cysteine does not seem to reduce mortality, improve event-free survival, or prevent additional tumors in patients with head and neck cancer. Details: Taking N-acetyl cysteine orally does not prevent second primary tumors in patients with head and neck cancer (1710). Also, N-acetyl cysteine alone, or in combination with retinyl palmitate, has no effect on mortality or event-free survival in these patients (1710).
• Lung cancer. Oral N-acetyl cysteine does not seem to reduce mortality, improve event-free survival, or prevent additional tumors in patients with lung cancer. Details: Taking N-acetyl cysteine orally does not prevent second primary tumors in patients with lung cancer (1710). Also, N-acetyl cysteine alone, or in combination with retinyl palmitate, has no effect on mortality or event-free survival in these patients (1705,1710).
• Multisystem organ failure. Administering intravenous N-acetyl cysteine might increase the risk of mortality due to multisystem organ failure. Oral N-acetyl cysteine has not been evaluated for this use. Details: Administering N-acetyl cysteine intravenously, greater than 24 hours after hospital admission, might increase mortality rate due to multisystem organ failure. The effect of N-acetyl cysteine given within 24 hours of hospital admission requires further study (7871).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Acute respiratory distress syndrome (ARDS). Research on the use of intravenous N-acetyl cysteine in patients with ARDS is conflicting. Oral N-acetyl cysteine has not been evaluated for this purpose. Details: Some clinical research shows that N-acetyl cysteine might reduce mortality and improve oxygenation in patients with acute lung injury/ARDS when compared with a control (64619). These patients were administered intravenous N-acetyl cysteine 150 mg/kg on the first day followed by 50 mg/kg for 3 more days. However, other clinical research shows that administering intravenous N-acetyl cysteine 40 mg/kg daily for 3 days does not reduce the risk of ARDS development in patients with acute lung injury (64771). Also, some clinical research shows that intravenous N-acetyl cysteine for up to 6 days does not reduce the time for improvement in patients with ARDS (64492). These discrepancies may be due to variations in genes involved in glutathione-S-transferase (GST) expression (64619).
• Adrenoleukodystrophy (ALD). It is unclear if oral or intravenous N-acetyl cysteine is beneficial in patients with ALD. Details: A case series of three male children with this rare condition suggests that administering N-acetyl cysteine orally and intravenously might improve overall survival and stabilize neurologic status after hematopoietic stem cell transplantation when compared with historical controls (64547).
• Aging. Oral N-acetyl cysteine has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in older adults shows that taking a combination product containing N-acetyl cysteine 100 mg/kg, glycerine 100 mg/kg, and alanine 200 mg/kg orally daily for 16 weeks modestly improved waist circumference, systolic blood pressure, and some serum markers of oxidative stress, but not body-mass index or diastolic blood pressure, when compared with placebo (110624). It is unclear if this effect is due to N-acetyl cysteine, other ingredients, or the combination.
• Alcohol-related liver disease. Although there has been interest in using oral N-acetyl cysteine for preventing alcohol-related liver damage, there is insufficient reliable information about the clinical effects of N-acetyl cysteine for this purpose.
• Allergic rhinitis (hay fever). Although there has been interest in using oral N-acetyl cysteine for allergic rhinitis, there is insufficient reliable information about the clinical effects of N-acetyl cysteine for this condition.
• Altitude sickness. It is unclear if oral N-acetyl cysteine can treat or prevent altitude sickness. Details: One very small clinical trial shows that taking N-acetyl cysteine 400 mg daily does not reduce altitude-associated anorexia or improve food intake in individuals exposed to high altitudes when compared with either placebo or vitamin E 400 mg daily (64599).
• Alzheimer disease. It is unclear if oral N-acetyl cysteine is beneficial for Alzheimer disease. Details: One clinical trial in a small number of patients with Alzheimer disease shows that taking N-acetyl cysteine 50 mg/kg daily for 6 months does not improve most cognitive symptoms of Alzheimer disease when compared with placebo (7870). However, preliminary clinical research in adults with mild to moderate Alzheimer disease also shows that taking a combination product containing N-acetyl cysteine 2.55 grams, L-serine 12.35 grams, nicotinamide riboside 1 gram, and L-carnitine tartrate 3.73 grams orally once daily for 28 days followed by twice daily for 56 more days improves cognitive functioning scores by 14% to 29% when compared with placebo (110623). It is unclear if this effect is due to N-acetyl cysteine, other ingredients, or the combination.
• Aminoglycoside ototoxicity. Small clinical studies suggest that oral N-acetyl cysteine may modestly reduce the risk of ototoxicity caused by aminoglycoside therapy. Details: A meta-analysis of available clinical research in adults with kidney failure receiving aminoglycosides for bloodstream infections shows that taking N-acetyl cysteine 600 mg twice daily for a total of 14 days, or for up to 7 days after completion of aminoglycoside therapy, reduces the risk of hearing loss by 33% when compared with placebo. The findings of this analysis are limited by the small sample sizes and high risk of bias of the included studies (97049).
• Asthma. It is unclear if inhaling N-acetyl cysteine is beneficial in patients with asthma. Details: Preliminary clinical research shows that, when administered as an aerosol daily for one week in combination with isoproterenol, N-acetyl cysteine 10% improves lung capacity and decreases sputum viscosity when compared with placebo in patients with asthma (64674).
• Athletic performance. It is unclear if oral N-acetyl cysteine can improve athletic performance. Details: Some small clinical studies shows that N-acetyl cysteine might be beneficial if taken orally at a dose of 1200 mg daily for 9 days leading up to exercise or when administered intravenously both before and during exercise (64529,91248), but that it might not improve performance when taken as a single 20 mg/kg oral dose 60 minutes prior to exercise (102028).
• Biliary disorders. It is unclear if intravenous N-acetyl cysteine is beneficial in patients with biliary disorders. Oral N-acetyl cysteine has not been evaluated for this use. Details: Preliminary clinical research in patients undergoing surgical bypass for obstructive jaundice shows that postoperative intravenous N-acetyl cysteine for 48 hours reduces levels of some liver enzymes, but not bilirubin levels or mean hospital stay, when compared with a control group. Although all liver enzyme levels had not returned to normal by 30 days after surgery, they were more improved in the group using N-acetylcysteine (102654).
• Bipolar disorder. The effects of oral N-acetyl cysteine in patients with bipolar disorder are conflicting. Oral N-acetyl cysteine might reduce symptoms of depression and increase remission rates, but it does not appear to be beneficial for reducing symptoms of mania or for maintaining remission. Details: One clinical study in patients with bipolar disorder shows that taking N-acetyl cysteine 1000 mg twice daily as adjunct to usual therapy for 24 weeks reduces symptoms of depression when compared with placebo (64608). A subgroup analysis of patients from this study who were diagnosed with bipolar II disorder shows that this dose of N-acetyl cysteine can increase the number of patients who achieve remission of both depression and mania, but not the number achieving remission of only one of these, when compared with placebo (91243). However, other research shows that taking N-acetyl cysteine 3 grams daily in addition to standard therapy for 20 weeks does not improve depression when compared with placebo in patients with bipolar depression experiencing a depressive episode for at least 4 weeks. A limitation of this study is the high (56%) placebo response rate, which might have limited the ability to detect between-group differences in symptoms improvements (99529). Taking N-acetyl cysteine as an adjunct to usual therapy does not appear to be beneficial for maintaining remission. A clinical study in patients with bipolar disorder shows that, although taking N-acetyl cysteine 1000 mg twice daily for 8 weeks improves symptoms of bipolar disorder when compared to baseline, maintenance therapy with N-acetyl cysteine for an additional 6 months does not improve depression symptoms or prevent recurrence when compared with placebo (91234).
• Bronchiectasis. Oral N-acetyl cysteine has been evaluated in patients with bronchiectasis, with promising results. Details: Preliminary clinical research in Chinese adults with bronchiectasis shows that taking N-acetyl cysteine 600 mg twice daily for 12 months reduces the risk of exacerbation by 59% when compared with a control group receiving on-demand treatment only. For every eight patients treated with N-acetyl cysteine, one additional patient was free of exacerbations at 12 months when compared with on-demand treatment only (102027).
• Canker sores. It is unclear if rinsing the mouth with N-acetyl cysteine solution is beneficial in patients with canker sores. Details: Preliminary clinical research in patients with recurrent canker sores shows that rinsing the mouth with N-acetyl cysteine (ACC, HEXAL AG) 200 mg dissolved in water for 30 seconds is no more effective than 0.12% chlorhexidine digluconate for canker sore healing time or level of pain. However, pain was reduced by 50% to 90% more over baseline 2-4 days after use of N-acetyl cysteine when compared with 0.12% chlorhexidine digluconate (102659).
• Chemotherapy-induced hepatotoxicity. It is unclear if intravenous N-acetyl cysteine is beneficial in patients with chemotherapy-induced hepatotoxicity. Oral N-acetyl cysteine has not been evaluated for this use. Details: Some observational research in children aged 2-17 years with chemotherapy-induced hepatotoxicity has found that intravenous N-acetyl cysteine 3 mcg/kg over 24 hours is associated with day-to-day improvement in liver injury, based on liver function enzyme levels, when compared with no N-acetyl cysteine therapy. Decreases in liver enzymes also occurred earlier in patients using N-acetyl cysteine (102664).
• Chemotherapy-induced peripheral neuropathy. Small clinical studies suggest that oral N-acetyl cysteine may reduce the risk for peripheral neuropathy in patients receiving oxaliplatin. Details: One preliminary clinical study in patients with colon cancer shows that taking N-acetyl cysteine 1200 mg orally at 1.5 hours prior to oxaliplatin therapy reduces the incidence of oxaliplatin-induced neuropathy when compared with placebo (64505). Another small clinical trial in patients with gastric or colorectal cancers shows that taking N-acetyl cysteine (Osveh Pharmaceutical Company) 1200 mg one hour before receiving oxaliplatin during eight courses of chemotherapy reduces the incidence and severity of neurotoxicity symptoms when compared with placebo. In patients taking N-acetyl cysteine, 31% had no signs of neurotoxicity after oxaliplatin chemotherapy, compared with 0% of those taking placebo. Also, 44% had mild symptoms, compared with 6% of those taking placebo. However, there were no significant differences in electrophysiological sensory results (102665).
• Chronic fatigue syndrome (CFS). Although there has been interest in using oral N-acetyl cysteine for CFS, there is insufficient reliable information about the clinical effects of N-acetyl cysteine for this purpose.
• Chronic kidney disease (CKD). Oral N-acetyl cysteine does not seem to improve kidney function in patients with CKD or reduce the risk of kidney injury or other complications after cardiac surgery in patients with CKD. However, intravenous N-acetyl cysteine might offer some benefit in patients with CKD undergoing cardiac surgery. Details: Clinical research shows that taking N-acetyl cysteine 1200 mg orally daily in combination with standard antihypertensive drugs does not reduce proteinuria or other markers of kidney injury in patients with CKD (64627). N-acetyl cysteine has also been evaluated for the prevention of acute kidney injury following cardiac surgery in patients with CKD, with conflicting results. Several meta-analyses have shown that N-acetyl cysteine does not reduce the incidence of acute kidney injury, postoperative complications, postoperative interventions, length of hospitalization, or mortality after cardiac surgery in adults with CKD (95766,95767,95768). However, these meta-analyses found that intravenous, but not oral, N-acetyl cysteine might be beneficial (95767,95768). A more recent meta-analysis shows that intravenous N-acetyl cysteine reduces the risk of postoperative acute kidney injury by 23% and reduces the risk of cardiac adverse events by 17% (99533). However, most of the studies included in this latter meta-analysis were small and the definition of cardiac events varied among the included studies. Higher quality research is needed to determine the benefit, if any, of N-acetyl cysteine in reducing acute kidney injury after cardiac surgery in patients with CKD.
• Cocaine dependence. It is unclear if oral N-acetyl cysteine is effective for reducing cravings or withdrawal symptoms in people trying to stop cocaine use. Details: Some preliminary clinical research shows that taking N-acetyl cysteine 600 mg twice daily for 2 days reduces the desire to use cocaine when compared with placebo in individuals with cocaine dependence (64563). However, other preliminary clinical research shows that taking oral N-acetyl cysteine 600 mg twice daily for 2 days does not reduce cravings or withdrawal symptoms when compared with placebo in patients hospitalized for cocaine dependency (64504).
• Colorectal cancer. It is unclear if oral N-acetyl cysteine is effective for preventing colorectal cancer. Details: Clinical research in a small group of patients with a history of adenomatous colonic polyps shows that taking N-acetyl cysteine 800 mg daily for 12 weeks reduces the proliferative index of colonic crypts, suggesting that N-acetyl cysteine might decrease the likelihood of colorectal cancer (7873).
• Coronary artery bypass graft (CABG) surgery. It is unclear if oral or intravenous N-acetyl cysteine is beneficial in patients undergoing CABG surgery. Details: A small clinical study shows that taking N-acetyl cysteine 300 mg orally in addition to intermittent blood cardioplegia does not affect postoperative outcomes or the risk of mortality when compared with control in patients undergoing elective CABG surgery (64638). Another small clinical study shows that giving N-acetyl cysteine 100 mg/kg by intravenous infusion, for two doses during CABG surgery and one postoperative dose, seems to reduce serum creatinine levels at 4 and 48 hours after surgery and reduce the incidence of acute kidney injury when compared with placebo. However, serum creatinine levels were within the normal range in all patients (106886).
• Coronavirus disease 2019 (COVID-19). Small clinical trials suggest that intravenous N-acetyl cysteine is not beneficial in patients at risk for respiratory failure from severe COVID-19. It is unclear if oral use is beneficial. Details: A small single-center clinical trial of patients presenting to the emergency room with COVID-19 pneumonia in Brazil shows that receiving intravenous N-acetyl cysteine 21 grams in dextrose 5% over 20 hours in conjunction with institutional standard care, including empiric antibiotics, does not reduce the need for mechanical ventilation, length of intensive care unit (ICU) stay, or mortality when compared with dextrose 5% (105560). Another small single-center clinical trial in patients with COVID-19 and acute respiratory distress syndrome (ARDS) in Iran shows that receiving a continuous intravenous infusion of N-acetyl cysteine 40 mg/kg in dextrose 5% daily for 3 days in conjunction with institutional standard care, including corticosteroids, vitamin C, vitamin D, and zinc, also does not reduce the need for mechanical ventilation, length of ICU stay, or mortality when compared with dextrose 5% (105561). Similarly, a retrospective study of patients hospitalized in Italy for COVID-19 pneumonia shows that receiving intravenous N-acetyl cysteine 300 mg three times daily, switched to 600 mg twice daily if the patient was clinically stable, for a duration of least 5 days, does not improve inpatient mortality, ICU admission, length of ICU stay, or the incidence of atelectasis, when compared with no supplementation. At a 6-month follow-up, treatment with N-acetyl cysteine also did not appear to impact long-term outcomes in these patients (108449). In contrast, a small, retrospective study in hospitalized patients with moderate to severe COVID-19 pneumonia shows that taking oral N-acetyl cysteine, 600 mg twice daily for 10 days in addition to standard care, including empiric antibiotics, corticosteroids, and remdesivir, reduces the risk for severe respiratory failure requiring ventilator support and reduces mortality at 14 days in those with severe pneumonia when compared with standard care alone (106885). Prospective, randomized, double-blind trials are needed to confirm these findings.
• Dental plaque. It is unclear if mouthwash solutions containing N-acetyl cysteine can reduce dental plaque; higher concentrations may be more effective than lower concentrations. Details: Preliminary clinical research shows that using a mouthwash solution containing N-acetyl cysteine 10% four times daily for 7 days reduces dental plaque (64687). However, other clinical research shows that rinsing twice daily for 3 weeks with N-acetyl cysteine 1.25% does not reduce the development of plaque. In addition, N-acetyl cysteine 1.25% was not beneficial when used for 2 weeks as a treatment for experimental plaque (102662).
• Dry eye. Small clinical studies suggest that eye drops containing N-acetyl cysteine, with or without chitosan, might improve objective measures of dry eye. Details: Preliminary clinical research in patients with dry eye shows that using tear solution containing 20% N-acetyl cysteine every two hours for 2 months improves objective, but not subjective, symptoms of dry eye syndrome when compared with artificial tears (64705). A small clinical study in patients with moderate to severe dry eye disease shows that applying a specific product (Lacrimera) containing chitosan-N-acetyl cysteine as one drop once or twice daily improves tear film thickness (TFT) after 10 minutes of application, and is maintained for 24 hours, when compared with placebo. Once or twice daily application does not seem to alter the level of benefit (97710). It is unclear if the benefit of this combination product is due to N-acetyl cysteine, chitosan, or the combination.
• Endometriosis. Oral N-acetyl cysteine has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in adults with endometriosis-associated pelvic pain shows that taking a combination product containing N-acetyl cysteine 1200 mg, alpha lipoic acid 400 mg, bromelain 50 mg, and zinc 20 mg daily for 6 months improves pain and reduces analgesic intake when compared to baseline (99535). This study was limited by a lack of comparator group.
• Esophagogastroduodenoscopy (EGD). It is unclear if N-acetyl cysteine (NAC) can improve visualization when used as a premedication for EGD. Details: Clinical research shows that giving NAC orally, 600 mg in 90 mL of an emulsion formulation, 20 minutes prior to EGD reduces foaming and mucus, allowing better visualization of the mucosa. The percentage of patients with no bubbles affecting visualization is about 51% with NAC, compared with 34% with placebo. The percentage not requiring suction or endoscopic flushes is 50% with NAC and 27% with placebo. Giving simethicone 150 mg in combination with NAC further improves visualization (108941).
• Exercise-induced muscle damage. It is unclear if oral N-acetyl cysteine is effective for preventing or treating exercise-induced muscle damage. Details: One small clinical study shows that taking N-acetyl cysteine 20 mg/kg daily in three divided doses after muscle-damaging exercise does not improve muscle repair or inflammatory response in healthy patients taking part in a specific resistance training program (91244).
• Fibrocystic breast disease. It is unclear if oral N-acetyl cysteine is effective for fibrocystic beast disease. Details: Preliminary clinical research in adult females with fibrocystic breast disease and cyclical mastalgia shows that taking N-acetyl cysteine (Osvah Pharmaceutical Company) 600 mg orally once daily for 12 weeks modestly improves pain scores when compared with placebo (109938).
• Gingivitis. It is unclear if mouthwash containing N-acetyl cysteine is effective for the prevention or treatment of gingivitis. Details: Clinical research shows that rinsing twice daily for 3 weeks with N-acetyl cysteine 1.25% is slightly more effective than placebo for reducing the development of gingivitis. However, there was no effect on plaque. In addition, N-acetyl cysteine is not as effective as chlorhexidine 0.2% and had no benefit when used for 2 weeks as a treatment for experimental gingivitis (102662).
• Hangover. Although there has been interest in using oral N-acetyl cysteine for treating hangovers, there is insufficient reliable information about the clinical effects of N-acetyl cysteine for this purpose.
• Hearing loss. It is unclear if oral N-acetyl cysteine is effective for preventing or treating hearing loss. Details: A meta-analysis of clinical trials in adults shows that taking N-acetyl cysteine 900-2700 mg orally daily for up to 42 days modestly protects against noise-induced hearing loss in middle to high hearing thresholds (0 to 4 kHz and 0 to 6 kHz), but not low hearing thresholds (0 to 2 kHz), when compared with control. However, the validity of this study is limited by high heterogeneity (109937). Another meta-analysis of 2 clinical trials in adults with sudden hearing loss shows that taking N-acetyl cysteine 1200 mg orally daily for 2 weeks to 3 months moderately improves pure tone threshold hearing when compared with control (109940).
• Hepatorenal syndrome. It is unclear if intravenous N-acetyl cysteine is beneficial in patients with hepatorenal syndrome. Oral N-acetyl cysteine has not been evaluated for this use. Details: A case series of 12 patients with hepatorenal syndrome reported that intravenous N-acetyl cysteine, starting with a 150 mg/kg loading dose over 2 hours, followed by a continuous infusion of 100 mg/kg daily for 5 days, modestly improved kidney function, but not liver function or blood pressure. When compared with historical controls, N-acetyl cysteine administration was also associated with an improvement in total survival time (1752). Prospective clinical studies are needed to confirm these findings.
• Hereditary hemorrhagic telangiectasia (HHT). It is unclear if oral N-acetyl cysteine is beneficial in patients with HHT. Details: One small clinical study shows that taking N-acetyl cysteine 600 mg three times daily orally for 12 weeks decreases the frequency and severity of daytime nosebleeds, but not nighttime nosebleeds, when compared to baseline in individuals with HHT (64643). The validity of these findings is limited by the lack of a comparator group.
• Idiopathic interstitial pneumonia. It is unclear if oral or inhaled N-acetyl cysteine is beneficial for the management of various forms of interstitial pneumonia. Details: A very small clinical study in patients with idiopathic interstitial pneumonia shows that taking N-acetyl cysteine 600 mg three times daily for 12 weeks seems to improve pulmonary function tests and decrease biochemical markers of disease when compared with baseline (7868). However, a meta-analysis of clinical research in patients with idiopathic pulmonary fibrosis, a specific type of interstitial pneumonia, shows that oral or inhaled N-acetyl cysteine does not reduce the risk of acute exacerbations or attenuate decline of lung function as measured by forced vital capacity (FVC), when compared with placebo (99538).
• Lead toxicity. Although there has been interest in using oral N-acetyl cysteine for lead toxicity, there is insufficient reliable information about the clinical effects of N-acetyl cysteine for this purpose.
• Malaria. It is unclear if intravenous N-acetyl cysteine is beneficial as an adjunct in treating malaria. Oral N-acetyl cysteine has not been evaluated for this use. Details: One small clinical study shows that intravenous N-acetyl cysteine, in combination with intravenous artesunate, does not reduce symptoms or the risk of mortality in patients with severe malaria when compared with artesunate alone (64630).
• Male infertility. It is unclear of oral N-acetyl cysteine is beneficial for male infertility. Details: Clinical research in adults with idiopathic oligoasthenoteratospermia shows that taking N-acetyl cysteine 600 mg orally daily for 26 weeks improves sperm concentration, but not sperm motility, when compared with placebo (64626). Additionally, a preliminary clinical study in adults with asthenoteratozoospermia shows that taking N-acetyl cysteine 600 mg daily for 3 months improves sperm motility and concentration, increases protamine, and improves hormone levels and sperm morphology when compared to baseline (99534). The validity of this study is limited by the lack of a comparator group. There is also interest in using N-acetyl cysteine to attenuate the infertility effects observed after COVID-19 infection. A large clinical study in males who had normal sperm analysis prior to COVID-19, but with significantly lower sperm parameters within 6 weeks after infection, shows that taking oral N-acetyl cysteine 600 mg daily for 3 months improves sperm volume, concentration, morphology, and total motility when compared with baseline post-COVID-19 levels (108447). Although the study enrolled a control group, the investigators did not provide a statistical comparison of outcomes between groups, limiting the validity of this finding.
• Mercury toxicity. Although there has been interest in using oral N-acetyl cysteine for mercury toxicity, there is insufficient reliable information about the clinical effects of N-acetyl cysteine for this purpose.
• Miscarriage. Oral N-acetyl cysteine has only been evaluated in combination with other ingredients; its benefit when used alone is unclear. Details: One small clinical trial shows that taking oral N-acetyl cysteine 600 mg daily with folic acid 500 mcg daily improves the likelihood of maintaining pregnancy past 20 weeks when compared with folic acid alone in adults with a history of recurrent pregnancy loss (64616).
• Multiple sclerosis (MS). It is unclear if oral and intravenous N-acetyl cysteine are beneficial in patients with MS. Details: One clinical trial in a small group of patients with MS shows that intravenous and oral N-acetyl cysteine in addition to standard care for 2 months improves self-reported cognition by a moderate amount when compared with standard care alone. Self-reported attention also seems to improve (102657).
• Nitrate tolerance. Intravenous N-acetyl cysteine seems to reduce the development of nitrate tolerance. Oral N-acetyl cysteine has shown mixed results for this use. Details: Some clinical research shows that concurrent intravenous or oral administration of N-acetyl cysteine reduces the development of nitroglycerin tolerance (832,2245,64546). However, other research suggests that oral N-acetyl cysteine does not reduce the development of nitroglycerin tolerance in patients with angina (2281,2282).
• Nonalcoholic steatohepatitis (NASH). It is unclear if oral N-acetyl cysteine is beneficial in patients with NASH. Details: One small clinical study in patients with NASH shows that taking N-acetyl cysteine 1.2 grams with metformin 850-1500 mg daily for 48 weeks reduces NASH activity scores and measures of steatosis and hepatocellular ballooning, but not inflammation or fibrosis, when compared to baseline. However, taking the same dose of N-acetyl cysteine and metformin along with ursodeoxycholic acid 15 mg/kg daily does not improve these outcomes, or improve liver enzyme levels, when compared with baseline (102026). The reasons for these disparate findings are unclear. Inadequate statistical power and the lack of a comparator group limit the validity of these findings.
• Obsessive-compulsive disorder (OCD). Oral N-acetyl cysteine might improve some symptoms of OCD when used with fluvoxamine in adults. Its effects when used in combination with other psychiatric medications or as monotherapy in children and adults is unclear. Details: Preliminary clinical research in adults shows that taking N-acetyl cysteine 1000 mg twice daily along with fluvoxamine 200 mg daily for 10 weeks modestly reduces overall symptoms of OCD and symptoms of obsession when compared with fluvoxamine alone. However, the addition of N-acetyl cysteine is not associated with an improvement in symptoms of compulsion, nor with a statistically significant increase in partial or complete responders, when compared with fluvoxamine alone (97048). A clinical trial in adults with OCD who are taking various psychiatric medications shows that adding oral N-acetyl cysteine 2000-4000 mg daily for 20 weeks does not reduce symptoms of OCD, or improve secondary outcomes such as anxiety, mood, functioning, or quality of life, when compared with placebo (108450). Over half (63%) of patients had a comorbid psychiatric diagnosis, limiting the applicability of these findings. Other preliminary clinical research in adults with moderate to severe OCD who are taking various psychiatric medications shows that taking N-acetyl cysteine 3000 mg daily for 16 weeks does not improve OCD symptoms when compared with placebo (97045). A very small preliminary clinical trial in children aged 8-17 years, most of whom are not taking psychiatric medications, shows some benefit for symptom reduction when N-acetyl cysteine 2700 mg daily for 12 weeks is compared with placebo (102656).
• Otitis media. Although there has been interest in using ear drops containing N-acetyl cysteine for otitis media, there is insufficient reliable information about the clinical effects of N-acetyl cysteine for this purpose.
• Polycystic ovary syndrome (PCOS). Oral N-acetyl cysteine might improve pregnancy-related outcomes in PCOS, although it appears to be less effective than metformin. Evidence on its benefits for other symptoms of PCOS is conflicting. Details: Some research in patients with PCOS shows that N-acetyl cysteine can increase insulin sensitivity, improve hirsutism, and improve menstrual irregularity (64435,64550,91245,102121). It may also improve fasting insulin levels, but results are conflicting (64435,64550,91245). Other research shows that N-acetyl cysteine, alone or as a specific combination product (Ovaric HP, Just Pharma), increases ovulation rates in some, but not all, patients with PCOS (64480,64550,64553,91246,91247,102121). A meta-analysis of clinical research suggests that N-acetyl cysteine increases the odds of having a live birth, getting pregnant, and/or ovulating by about 3-fold when compared with placebo. Its effects on the odds of pregnancy and ovulation appear to be greater in those resistant to clomiphene citrate. However, when compared with metformin, N-acetyl cysteine appears to decrease the odds of getting pregnant by about 60% and decrease the odds of ovulation by about 87%. N-acetyl cysteine also does not appear to reduce the rate of miscarriage, menstrual irregularity, or the severity of acne or hirsutism in people with PCOS (93057). Another meta-analysis shows that N-acetyl cysteine in various doses is associated with an insignificant improvement in ovulation and pregnancy rate, multiple pregnancy rate, and miscarriage rate, and is less efficacious than metformin for all of these outcomes (106888).
• Post-traumatic stress disorder (PTSD). It is unclear if oral N-acetyl cysteine is beneficial in veterans with PTSD. Details: A small clinical study in veterans with PTSD and a history of substance use disorders shows that taking N-acetyl cysteine 1200 mg orally twice daily for 8 weeks while receiving cognitive behavioral therapy reduces depressive symptoms and the rate of self-reported PTSD symptoms when compared with cognitive behavioral therapy plus placebo. Additionally, receiving N-acetyl cysteine reduces the amount and frequency of cravings by 81% and 72%, respectively, compared to a reduction of 32% and 29% for those receiving cognitive behavioral therapy with placebo. The use of N-acetyl cysteine did not impact the intensity of cravings or the actual rate of substance use during the study, which was low for all patients (97037).
• Postmenopausal conditions. It is unclear if oral N-acetyl cysteine is beneficial for preventing postmenopausal bone loss. Details: One small clinical trial shows that taking N-acetyl cysteine 2 grams daily for 3 months does not reduce postmenopausal bone loss when compared with placebo (64576).
• Preterm labor. It is unclear if oral N-acetyl cysteine is beneficial for reducing the risk for preterm labor. Details: Some clinical research shows that taking N-acetyl cysteine 0.6 grams daily orally in combination with 17-hydroxyprogesterone caproate (17-OHPC), beginning at 16 to 18 weeks gestation and continuing until active labor, increases the likelihood of reaching 36 weeks gestation and increases gestational age at delivery in adults with previous preterm labor and bacterial vaginosis when compared with 17-OHPC alone (64615). However, taking oral N-acetyl cysteine 0.6 grams every 8 hours, beginning at 25 to 33 weeks gestation and continuing until delivery, does not improve the treatment-to-delivery interval when compared with placebo in adults with early onset severe pre-eclampsia and/or HELLP (hemolysis, elevated liver enzymes, low platelets) syndrome (64493).
• Radiation-induced sialadenitis. It is unclear if mouthwash containing N-acetyl cysteine is beneficial for reducing dry mouth during chemoradiotherapy. Details: One clinical trial in a small group of patients undergoing chemoradiotherapy for head and neck cancer shows that using a mouth rinse containing N-acetyl cysteine 500 mg five times daily during radiotherapy and 2 weeks postradiotherapy improves daytime and total sticky saliva and feelings of dry mouth by up to 38% when compared with placebo. However, N-acetyl cysteine does not seem to improve nighttime symptoms (102661).
• Schizophrenia. Oral N-acetyl cysteine seems to improve negative symptoms of schizophrenia. The benefits of N-acetyl cysteine on positive symptoms of schizophrenia are less clear. Details: A meta-analysis of clinical research shows that taking N-acetyl cysteine for at least 6 months has a small to moderate effect on negative symptoms when compared with placebo. However, taking N-acetyl cysteine for only 8 weeks does not reduce negative symptoms, suggesting that a longer duration of treatment may be necessary (102658). Individual clinical studies show that N-acetyl cysteine does not improve positive symptoms, social function, cognition, and clinical global impression when compared with placebo (64605,99528). However, a meta-analysis of available research shows that taking N-acetyl cysteine for any duration has a small effect on positive symptoms, a moderate effect on working memory, and a large effect on overall symptoms (102658). It is possible that many individual studies were underpowered to detect a difference.
• Sepsis. Small clinical studies suggest that intravenous N-acetyl cysteine may improve respiratory function and tissue oxygenation, but not mortality, in patients with septic shock. Details: Two small clinical studies show that intravenous N-acetyl cysteine might improve respiratory function and tissue oxygenation, but not mortality, in some patients with recently diagnosed septic shock when compared with placebo (64760,64797).
• Sjogren syndrome. Small clinical studies suggest that oral N-acetyl cysteine may improve ocular and oral manifestations of this condition. Details: Two small clinical studies in adults with Sjogren syndrome show that taking oral N-acetyl cysteine 200 mg three times daily for 4 weeks reduces eye soreness and irritability, bad breath, and daytime thirst when compared with a control group; however, objective signs of dry eye were not improved (64673,64812).
• Systemic lupus erythematosus (SLE). It is unclear if oral N-acetyl cysteine is beneficial in patients with SLE. Details: One small clinical trial shows that taking N-acetyl cysteine orally 2.4-4.8 grams daily for 3 months significantly reduces disease activity and fatigue when compared with placebo in patients with SLE (91242).
• Thrombocytopenia. Oral N-acetyl cysteine has only been evaluated in combination with other ingredients, its effect when used alone is unclear. Details: A very small clinical study in adults with primary immune thrombocytopenia resistant or refractory to steroid therapy shows taking N-acetyl cysteine 400 mg every 8 hours with atorvastatin daily for at least one month at least doubles platelet count or increases it above 30 × 109/L compared to baseline in 60% of participants. However, 40% of participants did not respond to treatment (111572). It is unclear if this effect is due to N-acetyl cysteine, atorvastatin, or the combination. The validity of these findings is limited by the very small sample size, insufficient randomization, lack of a comparator group, and low retention rate, especially in the non-responder group.
• Tourette syndrome. It is unclear if oral N-acetyl cysteine is beneficial in patients with this condition. Details: One small clinical trial in children 8-17 years of age with Tourette syndrome shows that taking N-acetyl cysteine 600 mg twice daily for 2 weeks, followed by 1200 mg twice daily for the next 10 weeks, does not improve tic symptoms, premonitory urges, or the comorbid symptoms of obsessive-compulsive disorder (OCD), attention deficit-hyperactivity disorder (ADHD), anxiety, or depression when compared with placebo (97040).
• Trichotillomania. Oral N-acetyl cysteine might offer some benefit to adults, but not children, with trichotillomania. Details: One small clinical trial in adults shows that taking N-acetyl cysteine orally, in doses up to 2400 mg daily, significantly decreases the urge to pull hair, the amount of hair pulled, and patients' perception of their control over hair pulling as measured by a self-rating scale. After 12 weeks of treatment, scores decreased by 40% (16840). However, in children, taking N-acetyl cysteine in doses up to 2400 mg daily for 12 weeks does not seem to improve hair pulling when compared with placebo (91235).
• Ulcerative colitis. It is unclear if oral N-acetyl cysteine is beneficial in patients with ulcerative colitis. Details: One small clinical trial shows that oral N-acetyl cysteine 0.8 grams daily in combination with mesalamine 2.4 grams daily for 4 weeks does not improve the rate of clinical remission in individuals with ulcerative colitis when compared with mesalamine alone (64606).
• Urinary tract infections (UTIs). Oral N-acetyl cysteine has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Observational research in female breast cancer survivors has found that taking the combination of D-mannose 500 mg, N-acetyl cysteine 100 mg, and Morinda citrifolia fruit extract 200 mg daily for 2 months in addition to antibiotic therapy is associated with reduced recurrence of UTIs and urinary discomfort when compared with antibiotics alone (97360).
• Uterine fibroids. It is unclear if oral N-acetyl cysteine is beneficial in patients with uterine fibroids. Details: Preliminary clinical research shows that taking N-acetyl cysteine 600 mg daily for 12 weeks reduces the volume of uterine fibroids by about 25%, compared with a reduction of about 1% with placebo. N-acetyl cysteine also reduces painful and heavy menstrual bleeding when compared with placebo (106889).
• Wound healing. It is unclear if postoperative intravenous N-acetyl cysteine is beneficial in patients undergoing lower extremity amputation. Details: A clinical study in patients undergoing lower extremity amputation due to critical limb-threatening ischemia shows that receiving postoperative intravenous N-acetyl cysteine 1200 mg twice daily for 5 days, beginning within 3 hours after surgery, improves tissue perfusion from days 3 to 5 and amputation stump healing at day 30 in patients that are defined as high-risk, but not in the intent-to-treat population, when compared with placebo (108448). The validity of these findings is limited due to the short duration of treatment and the inclusion of both above-the-knee and below-the-knee amputations. More evidence is needed to rate N-acetyl cysteine for these uses.

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LIKELY SAFE ...when used orally in amounts commonly found in foods. Artichoke has Generally Recognized As Safe status (GRAS) for use in foods in the US (4912).

POSSIBLY SAFE ...when used orally and appropriately in medicinal amounts. Artichoke extract has been used with apparent safety at doses up to 3200 mg daily for up to 12 weeks (6282,15204,52235,91475,91478,100934). Artichoke leaf powder has been used with apparent safety at a dose of 1000 mg daily for up to 8 weeks (104133). Cynarin, a constituent in artichoke extract, has been used with apparent safety at daily doses of 750 mg daily for up to 3 months or 60 mg daily for up to 7 months (1423,1424,52222,52223,52236).

PREGNANCY AND LACTATION:
There is insufficient reliable information available about the safety of artichoke when used in medicinal amounts during pregnancy or lactation; avoid amounts greater than those found in foods.

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LIKELY SAFE ...when used orally and appropriately. A specific milk thistle extract standardized to contain 70% to 80% silymarin (Legalon, Madaus GmbH) has been safely used in doses up to 420 mg daily for up to 4 years (2613,2614,2616,7355,63210,63212,63278,63280,63299,63340)(88154,97626,105792). Higher doses of up to 2100 mg daily have been safely used for up to 48 weeks (63251,96107,101150). Another specific milk thistle extract of silymarin (Livergol, Goldaru Pharmaceutical Company) has been safely used at doses of 140 mg daily for up to 6 months and doses of 420 mg daily for up to 6 weeks (95021,95029,102851,102852,105793,105794,105795,113979). Some isolated milk thistle constituents also appear to be safe. Silibinin (Siliphos, Thorne Research) has been used safely in doses up to 320 mg daily for 28 days (63218). Some combination products containing milk thistle and other ingredients also appear to be safe. A silybin-phosphatidylcholine complex (Silipide, Inverni della Beffa Research and Development Laboratories) has been safely used in doses of 480 mg daily for 7 days (7356) and 240 mg daily for 3 months (63320). Tree turmeric and milk thistle capsules (Berberol, PharmExtracta) standardized to contain 60% to 80% silybin have been safely used twice daily for up to 12 months (95019,96140,96141,96142,97624,101158).

POSSIBLY SAFE ...when used topically and appropriately, short-term. A milk thistle extract cream standardized to silymarin 0.25% (Leviaderm, Madaus GmbH) has been used safely throughout a course of radiotherapy (63239). Another milk thistle extract cream containing silymarin 1.4% has been used with apparent safety twice daily for 3 months (105791,110489). A cream containing milk thistle fruit extract 25% has been used with apparent safety twice daily for up to 12 weeks (111175). A milk thistle extract gel containing silymarin 1% has been used with apparent safety twice daily for 9 weeks (95022). There is insufficient reliable information available about the safety of intravenous formulations of milk thistle or its constituents.

PREGNANCY AND LACTATION:
While research in an animal model shows that taking milk thistle during pregnancy and lactation does not adversely impact infant development (102850), there is insufficient reliable information available about its safety during pregnancy or lactation in humans; avoid using.

CHILDREN: POSSIBLY SAFE
when used orally and appropriately, short-term. A milk thistle extract 140 mg three times daily has been used with apparent safety for up to 9 months (88154,98452). A specific product containing the milk thistle constituent silybin (Siliphos, Thorne Research Inc.) has been used with apparent safety in doses up to 320 mg daily for up to 4 weeks in children one year of age and older (63218).

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LIKELY SAFE ...when used orally, intravenously, intratracheally, or by inhalation and appropriately. N-acetyl cysteine is an FDA-approved prescription drug (832,1539,1705,1710,2245,2246,2252,2253,2254,2256)(2258,2259,2260,5808,6176,6611,7868,10270,10271,16840)(91243,91247,102027,102660,102666,99531).

CHILDREN: LIKELY SAFE
when used orally and appropriately. N-acetyl cysteine has been safely used at doses of 900-2700 mg daily for 8-12 weeks (91235,91239,91241,102666). ...when used intravenously and appropriately. Intravenous N-acetyl cysteine 140 mg/kg/day plus oral N-acetyl cysteine 70 mg/kg four times daily for up to 10 months has been safely used (64547).

PREGNANCY: POSSIBLY SAFE
when used orally, intratracheally, intravenously, or by inhalation. N-acetyl cysteine crosses the placenta, but has not been associated with adverse effects to the fetus (1711,64615,64493,97041). However, N-acetyl cysteine should only be used in pregnancy when clearly indicated, such as in cases of acetaminophen toxicity.

LACTATION:
Insufficient reliable information available; avoid using.

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ANTIDIABETES DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, artichoke leaf extract may increase the risk of hypoglycemia when taken with antidiabetes drugs.  Details A meta-analysis of small clinical studies shows that taking artichoke leaf extract for 8-12 weeks can modestly reduce fasting plasma glucose when compared with placebo (105768).

ANTIHYPERTENSIVE DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, artichoke leaf extract may increase the risk of hypotension when taken with antihypertensive drugs.  Details A meta-analysis of small clinical studies in patients with hypertension shows that taking artichoke can reduce systolic blood pressure by around 3 mmHg and diastolic blood pressure by around 2 mmHg when compared with placebo (105767).

CYTOCHROME P450 2B6 (CYP2B6) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, artichoke might increase serum levels of drugs metabolized by CYP2B6.  Details In vitro research shows that artichoke leaf extract inhibits CYP2B6 activity (97717). However, this interaction has not been reported in humans.

CYTOCHROME P450 2C19 (CYP2C19) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, artichoke might increase serum levels of drugs metabolized by CYP2C19.  Details In vitro research shows that artichoke leaf extract inhibits CYP2C19 activity (97717). However, this interaction has not been reported in humans.

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ANTIDIABETES DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Taking milk thistle with antidiabetes drugs may increase the risk of hypoglycemia.  Details Clinical research shows that milk thistle extract, alone or along with tree turmeric extract, can lower blood glucose levels and glycated hemoglobin (HbA1c) in patients with type 2 diabetes, including those already taking antidiabetes drugs (15102,63190,63314,63318,95019,96140,96141,97624,97626,113987).

CYTOCHROME P450 2B6 (CYP2B6) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, milk thistle might inhibit CYP2B6.  Details An in vitro study shows that silybin, a constituent of milk thistle, binds to and noncompetitively inhibits CYP2B6. Additionally, silybin might downregulate the expression of CYP2B6 by decreasing mRNA and protein levels (112229).

CYTOCHROME P450 2C9 (CYP2C9) SUBSTRATES Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Unlikely •  Level of Evidence = B It is unclear if milk thistle inhibits CYP2C9; research is conflicting.  Details In vitro research suggests that milk thistle might inhibit CYP2C9 (7089,17973,17976). Additionally, 3 case reports from the World Health Organization (WHO) adverse drug reaction database describe increased toxicity in patients taking milk thistle and cancer medications that are CYP2C9 substrates, including imatinib and capecitabine (111644). However, contradictory clinical research shows that milk thistle extract does not inhibit CYP2C9 or significantly affect levels of the CYP2C9 substrate tolbutamide (13712,95026). Differences in results could be due to differences in dosages or formulations utilized (95026).

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Unlikely •  Level of Evidence = D It is unclear if milk thistle inhibits CYP3A4; research is conflicting.  Details While laboratory research shows conflicting results (7318,17973,17975,17976), pharmacokinetic research shows that taking milk thistle extract 420-1350 mg daily does not significantly affect the metabolism of the CYP3A4 substrates irinotecan, midazolam, or indinavir (8234,17974,93578,95026). However, 8 case reports from the World Health Organization (WHO) adverse drug reaction database describe increased toxicity in patients taking milk thistle and cancer medications that are CYP3A4 substrates, including gefitinib, sorafenib, doxorubicin, and vincristine (111644).

ESTROGENS Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, milk thistle might interfere with estrogen therapy through competition for estrogen receptors.  Details Animal research suggests that a milk thistle extract of silymarin binds to estrogen receptor beta (93025,93026).

GLUCURONIDATED DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, milk thistle might affect the clearance of drugs that undergo glucuronidation.  Details Laboratory research shows that milk thistle constituents inhibit uridine diphosphoglucuronosyl transferase (UGT), the major phase 2 enzyme that is responsible for glucuronidation (7318,17973). Theoretically, this could decrease the clearance and increase levels of glucuronidated drugs. Other laboratory research suggests that a milk thistle extract of silymarin might inhibit beta-glucuronidase (7354), although the significance of this effect is unclear.

HMG-CoA REDUCTASE INHIBITORS ("Statins") Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Unlikely •  Level of Evidence = D Theoretically, milk thistle might interfere with statin therapy by decreasing the activity of organic anion transporting polypeptide 1B1 (OATB1B1) and inhibiting breast cancer resistance protein (BCRP).  Details Preliminary evidence suggests that a milk thistle extract of silymarin can decrease the activity of the OATP1B1, which transports HMG-CoA reductase inhibitors into the liver to their site of action, and animal research shows this increases the maximum plasma concentration of pitavastatin and pravastatin (113975). The silibinin component also inhibits BCRP, which transports statins from the liver into the bile for excretion. However, in a preliminary study in healthy males, silymarin 140 mg three times daily had no effect on the pharmacokinetics of a single 10 mg dose of rosuvastatin (16408).

INDINAVIR (Crixivan) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Unlikely •  Level of Evidence = B Theoretically, milk thistle may induce cytochrome P450 3A4 (CYP3A4) enzymes and increase the metabolism of indinavir; however, results are conflicting.  Details One pharmacokinetic study shows that taking milk thistle (Standardized Milk Thistle, General Nutrition Corp.) 175 mg three times daily in combination with multiple doses of indinavir 800 mg every 8 hours decreases the mean trough levels of indinavir by 25% (8234). However, results from the same pharmacokinetic study show that milk thistle does not affect the overall exposure to indinavir (8234). Furthermore, two other pharmacokinetic studies show that taking specific milk thistle extract (Legalon, Rottapharm Madaus; Thisilyn, Nature's Way) 160-450 mg every 8 hours in combination with multiple doses of indinavir 800 mg every 8 hours does not reduce levels of indinavir (93578).

LEDIPASVIR Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, milk thistle might increase the levels and clinical effects of ledipasvir.  Details Animal research in rats shows that milk thistle increases the area under the curve (AUC) for ledipasvir and slows its elimination (109505).

MORPHINE Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, concomitant use of milk thistle with morphine might affect serum levels of morphine and either increase or decrease its effects.  Details Animal research shows that milk thistle reduces serum levels of morphine by up to 66% (101161). In contrast, laboratory research shows that milk thistle constituents inhibit uridine diphosphoglucuronosyl transferase (UGT), the major phase 2 enzyme that is responsible for glucuronidation (7318,17973). Theoretically, this could decrease the clearance and increase morphine levels. The effect of taking milk thistle on morphine metabolism in humans is not known.

ORGANIC ANION-TRANSPORTING POLYPEPTIDE SUBSTRATES (OATP) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Milk thistle may inhibit one form of OATP, OATP-B1, which could reduce the bioavailability and clinical effects of OATP-B1 substrates.  Details In vitro research shows that milk thistle inhibits OATP-B1. Two case reports from the World Health Organization (WHO) adverse drug reaction database describe increased toxicity in patients taking milk thistle and cancer medications that are OATP substrates, including sorafenib and methotrexate (111644). OATPs are expressed in the small intestine and liver and are responsible for the uptake of drugs and other compounds into the body. Inhibition of OATP may reduce the bioavailability of oral drugs that are substrates of OATP.

P-GLYCOPROTEIN SUBSTRATES Interaction Rating = Minor Be watchful with this combination. Severity = Moderate •  Occurrence = Unlikely •  Level of Evidence = B Theoretically, milk thistle might increase the absorption of P-glycoprotein substrates. However, this effect does not seem to be clinically significant.  Details In vitro research shows that milk thistle can inhibit P-glycoprotein activity (95019,111644) and 1 case report from the World Health Organization (WHO) adverse drug reaction database describes increased abdominal pain in a patient taking milk thistle and the cancer medication vincristine, a P-glycoprotein substrate, though this patient was also taking methotrexate (111644). However, a small pharmacokinetic study in healthy volunteers shows that taking milk thistle (Enzymatic Therapy Inc.) 900 mg, standardized to 80% silymarin, in 3 divided doses daily for 14 days does not affect absorption of digoxin, a P-glycoprotein substrate (35825).

RALOXIFENE (Evista) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, milk thistle might decrease the clearance and increase levels of raloxifene.  Details Laboratory research suggests that the milk thistle constituents silibinin and silymarin inhibit the glucuronidation of raloxifene in the intestines (93024).

SIROLIMUS (Rapamune) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Milk thistle might decrease the clearance of sirolimus.  Details Pharmacokinetic research shows that a milk thistle extract of silymarin decreases the apparent clearance of sirolimus in hepatically impaired renal transplant patients (19876). It is unclear if this interaction occurs in patients without hepatic impairment.

SOFOSBUVIR (Solvaldi) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, milk thistle might decrease the levels and clinical effects of sofosbuvir.  Details Animal research in rats shows that milk thistle reduces the metabolism of sofosbuvir, as well as the hepatic uptake of its active metabolite (109505).

TAMOXIFEN (Nolvadex) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, the milk thistle constituent silibinin might increase tamoxifen levels and interfere with its conversion to an active metabolite.  Details Animal research suggests that the milk thistle constituent silibinin might increase plasma levels of tamoxifen and alter its conversion to an active metabolite. The mechanism appears to involve inhibition of pre-systemic metabolism of tamoxifen by cytochrome P450 (CYP) 2C9 and CYP3A4, and inhibition of P-glycoprotein-mediated efflux of tamoxifen into the intestine for excretion (17101). Whether this interaction occurs in humans is not known.

WARFARIN (Coumadin) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, milk thistle might increase the effects of warfarin.  Details In one case report, a man stabilized on warfarin experienced an increase in INR from 2.64 to 4.12 after taking a combination product containing milk thistle 200 mg daily, as well as dandelion, wild yam, niacinamide, and vitamin B12. Levels returned to normal after stopping the supplement (101159). Although a direct correlation between milk thistle and the change in INR cannot be confirmed, some in vitro research suggests that milk thistle might inhibit cytochrome P450 2C9 (CYP2C9), an enzyme involved in the metabolism of various drugs, including warfarin (7089,17973,17976).

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ACTIVATED CHARCOAL Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D N-acetyl cysteine might reduce the effects of activated charcoal, while activated charcoal might reduce the absorption of N-acetyl cysteine.  Details N-acetyl cysteine appears to reduce the capacity of activated charcoal to adsorb acetaminophen and salicylic acid (7869). Conversely, although clinical research suggests that although activated charcoal can reduce the absorption of N-acetyl cysteine by up to 40%, it does not seem to reduce its clinical effects (1755,22774,22775,64501,64647). Other clinical evidence suggests that activated charcoal does not affect the absorption of N-acetyl cysteine (22776,22777).

ANTICOAGULANT/ANTIPLATELET DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, N-acetyl cysteine might increase the risk of bleeding when taken with anticoagulant or antiplatelet drugs.  Details Clinical research suggests that intravenous N-acetyl cysteine decreases prothrombin time, prolongs coagulation time, decreases platelet aggregation, and increases blood loss in surgical patients (64511,64644). Furthermore, in vitro research suggests that N-acetyl cysteine increases the anticoagulant activity of nitroglycerin (22780,64780).

ANTIHYPERTENSIVE DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, N-acetyl cysteine might increase the risk of hypotension when taken with antihypertensive drugs.  Details Animal research suggests that N-acetyl cysteine potentiates the hypotensive effects of the angiotensin-converting enzyme inhibitors (ACEIs) captopril and enalaprilat (22785). Theoretically, combining N-acetyl cysteine with other antihypertensive drugs might increase the risk of hypotension.

CHLOROQUINE (Aralen) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, N-acetyl cysteine might interfere with the antimalarial effects of chloroquine.  Details Animal research suggests that N-acetyl cysteine might reduce the antimalarial effects of chloroquine by increasing cellular levels of glutathione (22786).

NITROGLYCERIN Interaction Rating = Major Do not take this combination. Severity = High •  Occurrence = Probable •  Level of Evidence = B N-acetyl cysteine can increase the risk for hypotension and headaches when taken with intravenous or transdermal nitroglycerin.  Details Clinical research shows that concomitant administration of N-acetyl cysteine and intravenous or transdermal nitroglycerin can cause severe hypotension (2246) and intolerable headaches (2245,2280). Furthermore, in vitro research suggests that N-acetyl cysteine increases the anticoagulant activity of nitroglycerin (22780,64780).

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General ...Orally, artichoke extract seems to be well tolerated.
Most Common Adverse Effects:
Orally: Abdominal pain, diarrhea, flatulence, hunger, and nausea.
Topically: Contact dermatitis in sensitive individuals.
Serious Adverse Effects (Rare):
Orally: Anaphylaxis to artichoke inulin has been reported in individuals sensitive to inulin.
Topically: Chest tightness, cough, and dyspnea after occupational exposure in sensitive individuals.

Dermatologic ...Artichoke can cause an allergic reaction in some patients. Patients sensitive to the Asteraceae/Compositae family may be at the greatest risk. Members of this family include ragweed, chrysanthemums, marigolds, daisies, and many other herbs. Topically, allergic contact dermatitis can occur with the use of artichoke. This has been attributed to the constituent cynaropicrin (11,52206,52226,52230). Redness in the face (11774) and sweating (91475) have been reported rarely following oral use of artichoke extract.
Occupational or airborne exposure to artichoke may also cause allergic reactions. In one case, a 52-year-old male presented with severe spongiotic dermatitis in exposed areas that was recurrent over the past 8 years. A patch test confirmed allergies to artichokes and sesquiterpene lactones, a group of allergens from the Compositae family, and the patient confirmed occupational and airborne exposure to artichokes during the time of his symptoms. The patient improved considerably after treatment with dupilumab (111565).

Gastrointestinal ...Orally, artichoke extract might increase abdominal discomfort, flatulence, diarrhea, hunger, and nausea in some patients (2562,52238,91475). Abdominal pain and a bitter taste in the mouth were reported by a single person following oral use of a dietary supplement containing artichoke extract, as well as red yeast rice, pine bark extract, and garlic extract (89452). It is not clear if this adverse effect was due to artichoke, other ingredients, or the combination.
In one case report, the autopsy of an 84-year-old female revealed a colonic bezoar comprised of artichoke fiber and fragments. This bezoar caused complete intestinal obstruction, leading to fatal acute peritonitis. Although rare, patients who lack adequate teeth and/or who have a history of gastric surgery are at increased risk for fibrous bezoar formation (97716).

Pulmonary/Respiratory ...Following occupational exposure, allergic symptoms including dyspnea, cough, chest tightness, and asthma symptoms or exacerbation have been reported. The effects were attributed to sensitization to artichoke. Subsequent nasal challenge with artichoke extract caused reduced nasal patency in these patients (52210,52230).
Orally, severe anaphylactic shock in response to artichoke inulin as an ingredient in commercially available products has been reported (52217). Individuals with a noted sensitivity to artichokes should consume inulin with caution. While rare, individuals with a known inulin allergy should avoid artichoke and artichoke extract.

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General ...Orally, milk thistle is well tolerated.
Most Common Adverse Effects:
Orally: Abdominal bloating, diarrhea, dyspepsia, flatulence, and nausea. However, these adverse effects do not typically occur at a greater frequency than with placebo.
Serious Adverse Effects (Rare):
Orally: Allergic reactions, including anaphylaxis, have been reported.

Dermatologic ...Orally, milk thistle may cause allergic reactions including urticaria, eczema, skin rash, and anaphylaxis in some people (6879,7355,8956,63210,63212,63238,63251,63315,63325,95029). Allergic reactions may be more likely to occur in patients sensitive to the Asteraceae/Compositae family (6879,8956). A case report describes a 49-year-old female who developed clinical, serologic, and immunopathologic features of bullous pemphigoid after taking milk thistle orally for 6 weeks. Symptoms resolved after treatment with prednisone and methotrexate (107376). Topically, milk thistle can cause erythema (110489).

Gastrointestinal ...Mild gastrointestinal symptoms have been reported, including nausea, vomiting, bloating, diarrhea, epigastric pain, abdominal colic or discomfort, dyspepsia, dysgeusia, flatulence, constipation, and loss of appetite (2616,6879,8956,13170,63140,63146,63160,63210,63218,63219)(63221,63244,63247,63250,63251,63320,63321,63323,63324,63325)(63327,63328,95024,95029,107374). There is one report of a 57-year-old female with sweating, nausea, colicky abdominal pain, diarrhea, vomiting, weakness, and collapse after ingesting milk thistle; symptoms subsided after 24-48 hours without medical treatment and recurred with re-challenge (63329).

Musculoskeletal ...In one clinical study three patients taking milk thistle 200 mg orally three times daily experienced tremor; the incidence of this adverse effect was similar for patients treated with fluoxetine 10 mg three times daily (63219).

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General ...Orally, intravenously, and as an inhalation, N-acetyl cysteine is generally well-tolerated when used in typical doses. Most adverse effects to N-acetyl cysteine occur when single doses of greater than 9 grams are used or when a regimen of greater than 30 grams daily is followed.
Most Common Adverse Effects:
Orally: Diarrhea, dry mouth, dyspepsia, heartburn, loss of appetite, nausea, and vomiting.
Intravenously: Skin rash and hypersensitivity reactions.
Inhaled: Bronchospasm, cough, epigastric pain, throat irritation, and wheezing.
Serious Adverse Effects (Rare):
Orally: Chest tightness, hemoptysis, and palpitations have been reported.
Intravenously: Anaphylaxis, angina, dystonic reactions, tachycardia, and transient sinus bradycardia have been reported.

Cardiovascular ...Intravenously, N-acetyl cysteine has been reported to significantly increase systolic and diastolic blood pressure after exposure to nitroglycerin when compared with placebo (2280). Tachycardia, chest pain, angina, and transient sinus bradycardia have been rarely reported after administration of intravenous N-acetyl cysteine (2280,7872,64658).
Intratracheally, infants receiving 5% N-acetyl cysteine every four hours for chronic lung disease have developed bradycardia (64490).
Orally, palpitations and chest tightness have been reported rarely in clinical research evaluating oral N-acetyl cysteine at doses up to 600 mg twice daily (64675,64717,64762).

Dermatologic ...Orally, N-acetyl cysteine may cause hives (64713,64739,64813), flushing (2260,64715), and edema (64714). Rash has also been reported (64510,64715,64717,102656). In one study, flushing was reported in 2% of patients receiving 600 mg of N-acetyl cysteine orally twice daily for six months (2260).
Intravenously, N-acetyl cysteine may cause rash, and the occurrence seems to be more common than with oral use (2254,64492,64562,64658,64759,64794). Hives (2280,64794), facial edema (2280), flushing (64412), and pruritus (64658,64763) have also been reported. In a small case series of 10 healthy male patients receiving 150 mg/kg of intravenous N-acetyl cysteine for muscle fatigue, erythema was experienced 30 minutes after infusion. Other side effects reported by these patients include facial erythema, palmar erythema, and sweating (64763). In other clinical research, three patients developed an erythematous flare at the sites of previous venipunctures after receiving 5.5 gm/m2 of N-acetyl cysteine with doxorubicin therapy (64712). Pain, inflammation, and excoriation of the skin have been reported after a 20% N-acetyl cysteine solution leaked from the catheter in one patient (64726).

Gastrointestinal ...Orally, gastrointestinal complaints are the most common adverse effects reported with N-acetyl cysteine. These include heartburn (64608,64715,64717,64738,64739,102666), dyspepsia (1710,64715,64717,64724,64738), and epigastric pain (2260,10429,64715,64717). In one case report, esophagitis related to ulcerations occurred following intake of N-acetyl cysteine while in the supine position with inadequate water (102655). Other common side effects include loss of appetite (64715,64812), flatulence (2256,64510), diarrhea (64713,64715,97049), constipation (64715), dry mouth (64715,64724), nausea (7868,11430,64715,64724,64738,64812,97049), vomiting (64717,64724,64715,97049), gastric upset (64510,64545,97045,97049), acid reflux (108450), changes in bowel habits (108450), and intolerance to taste and odor (64510,64545). N-acetyl cysteine's unpleasant odor makes it difficult for some patients to take orally. Using a straw to drink N-acetyl cysteine solutions can improve tolerability. Additionally, placement of a nasogastric or duodenal tube and administration of metoclopramide or ondansetron can be helpful for patients unable to tolerate oral N-acetyl cysteine (17).
Intravenously, N-acetyl cysteine may cause diarrhea (64712), dyspepsia, nausea, vomiting (64763), mild gastrointestinal upset (102657), and metallic taste (64763).
When inhaled, N-acetyl cysteine may cause epigastric pain and throat irritation (64703,64707,64674).

Genitourinary ...Orally, dysuria was reported in 2% of patients receiving 600 mg of N-acetyl cysteine twice daily for 6 months in one clinical trial (2260).

Hematologic ...In general, hematologic adverse reactions are reported more frequently with intravenous N-acetyl cysteine compared with oral use. In surgical patients, decreased prothrombin time (1341,64511), prolonged coagulation time (64511), increased blood loss (64511,64644), and decreased platelet aggregation (64511) have been reported after administration of IV N-acetyl cysteine. In one clinical trial, six healthy patients were administered a loading dose of IV N-acetyl cysteine 10 mg/kg followed by 10 mg/kg per hour for 32 hours. All patients experienced a decrease in prothrombin time by 30% to 40%. The decrease prothrombin time (25.4 sec to 20.6 sec) reached a steady state after 16 hours (1341). In a clinical trial evaluating patients with acute myocardial infarction, hemorrhage occurred in three patients taking intravenous N-acetyl cysteine 10 mg/min, heparin (per study protocol), and aspirin (7872). Two pediatric patients receiving intravenous N-acetyl cysteine (loading dose: 140 mg/kg followed by 70 mg/kg) experienced episodes of coagulopathy; however, patients were being treated for acetaminophen overdose (64794).
Hemoptysis was reported in six patients receiving 200 mg of N-acetyl cysteine orally twice daily for 6 months for treatment of chronic bronchitis (64739).

Immunologic ...Orally, anaphylaxis to N-acetyl cysteine has been rarely reported (64794). However, anaphylactic reactions to intravenous N-acetyl cysteine appear to be more common (1716,64412,64449,64628,64710,64711,64721,64786,64789).
Anaphylactic reactions to N-acetyl cysteine have involved rash, angioedema, hypotension, and bronchospasm (64449,64711,64720). The mechanism of this reaction is unclear, but some data suggest it is not an immunologic hypersensitivity reaction but rather an acute toxic effect of N-acetyl cysteine (64786,64641,64720). Management guidelines for the treatment of anaphylactoid reactions to intravenous N-acetyl cysteine have been published. In most cases, treatment is not required or treatment with diphenhydramine or salbutamol is sufficient to continue or restart N-acetyl cysteine infusion. Antihistamines are useful in controlling and preventing recurrence of anaphylactoid symptoms (1716).

Musculoskeletal ...In one clinical trial, joint pain was reported in more than 15% of patients receiving oral N-acetyl cysteine (64608). In other research, one patient experienced pain in the legs while taking 600 mg of N-acetyl cysteine twice daily for the treatment of chronic bronchitis (64762).

Neurologic/CNS ...Orally, headache has been frequently reported with N-acetyl cysteine in clinical research (7873,11430,64510,64608,64672,64713,64715,64724,64762). Other less common adverse effects reported in patients taking oral N-acetyl cysteine at a total daily dose of 600-1200 mg include dizziness (64715,64717,64724,64762), tiredness (64675,64717), vivid dreams (102666), disorientation, and inability to concentrate (64673). One pediatric patient receiving oral N-acetyl cysteine (loading dose: 140 mg/kg followed by 70 mg/kg) experienced encephalopathy (64794).
Intravenously, N-acetyl cysteine has been associated with rare neurologic adverse reactions , including headache (7872), lightheadedness (64763), and dystonic reactions (64794). In a previously healthy 2-year-old female, status epilepticus occurred during intravenous N-acetyl cysteine therapy for paracetamol ingestion (64781). Increased deterioration in bulbar function in patients with amyotrophic lateral sclerosis has also been reported with IV N-acetyl cysteine (2254).

Ocular/Otic ...While rare, blurred vision has been reported in research on oral N-acetyl cysteine (64715). Additionally, in a previously healthy 2-year-old female, status epilepticus followed by cortical blindness occurred during intravenous N-acetyl cysteine therapy for paracetamol ingestion. In this case, vision was almost completely recovered 18-months later (64781).

Psychiatric ...Intravenously, dysphoria was experienced 30 minutes after infusion of N-acetyl cysteine in 8 of 10 healthy males assessed in one clinical study (64763).

Pulmonary/Respiratory ...Respiratory adverse reactions to N-acetyl cysteine are most commonly reported with inhalable dosage forms. These include wheezing (64455,64707), bronchospasm (64455,64699), and cough (64455,64456,64703,64811). While less frequent, wheezing (64675), bronchospasm (64675), increased sputum production (7868), cough (7868,64510), decreased peak flow (64510), dyspnea (64714), and cold symptoms (64510) have been reported with oral N-acetyl cysteine in clinical research. A few cases of wheezing (64718,64719), cough (64763), and bronchospasm (64658) have also been reported with intravenous N-acetyl cysteine. Additionally, respiratory arrest has been reported in one case where a 16 year-old female was being treated for acetaminophen toxicity with intravenous N-acetyl cysteine (64450).
Two premature infants receiving 5% N-acetyl cysteine via intratracheal instillation for the treatment of chronic lung disease had an increased frequency of cyanotic spells (64490).

Other ...Injection site reactions, including burning and phlebitis, have been reported in patients receiving IV N-acetyl cysteine (1341,64763). Fever associated with IV N-acetyl cysteine was reported in one patient during clinical research (64759).

(Read more about N-ACETYL CYSTEINE (NAC))