Digestive Detox by Vinco

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Allergic rhinitis (hay fever). Although there is interest in using oral cat's claw for allergic rhinitis, there is insufficient reliable information about the clinical effects of cat's claw for this condition.
• Alzheimer disease. Although there is interest in using oral cat's claw for Alzheimer disease, there is insufficient reliable information about the clinical effects of cat's claw for this condition.
• Asthma. Although there is interest in using oral cat's claw for asthma, there is insufficient reliable information about the clinical effects of cat's claw for this condition.
• Atopic dermatitis (eczema). Oral cat's claw has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research shows that using a specific spray combination of cat's claw (Uncaria tomentosa) 1% and Rhealba oat plantlet extract 0.25% (Pierre Fabre Dermo Cosmetique) up to 6 times daily for 22 days subjectively reduces skin symptoms of atopic dermatitis when compared with baseline (103170). The validity of this finding is limited by the lack of a comparator group. Additionally, it is not clear whether the results are due to cat's claw, oat extract, spray excipients, or the combination.
• Cancer. It is unclear if oral cat's claw is beneficial for improving quality of life in patients with cancer. Details: Preliminary clinical research in patients with terminal advanced solid tumors shows that taking a specific cat's claw (Uncaria tomentosa) extract, standardized to 5% mitraphylline, 100 mg three times daily for at least 8 weeks improves quality of life, social functioning, and fatigue when compared with baseline (92502). The validity of this finding is limited by the lack of a comparator group.
• Chronic fatigue syndrome (CFS). Although there is interest in using oral cat's claw for CFS, there is insufficient reliable information about the clinical effects of cat's claw for this condition.
• Denture Stomatitis. It is unclear if oral cat's claw is beneficial for the treatment of denture stomatitis. Details: In patients with denture stomatitis, a small clinical trial shows that topical application of 2.5 mL of a gel containing cat's claw (Uncaria tomentosa) 2% to the base of dentures three times daily after meals for one week is as effective as miconazole 2% for improvement of symptoms. However, these treatments were also similarly effective to placebo (105186).
• Diarrhea. Although there is interest in using oral cat's claw for diarrhea, there is insufficient reliable information about the clinical effects of cat's claw for this purpose.
• Hemorrhoids. Although there is interest in using oral cat's claw for hemorrhoids, there is insufficient reliable information about the clinical effects of cat's claw for this purpose.
• Human papillomavirus (HPV). Oral cat's claw has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research shows that taking three tablets of a specific combination supplement containing cat's claw, echinacea, andrographis, grapefruit, papaya, and pau d'arco daily for one month reduces the recurrence of anal condylomata in patients following surgical removal of anal condylomata. After one month, recurrence was 4% in the supplement group compared with 18% in the control group; after six months the recurrence rates were 7% and 27%, respectively (20073). However, the validity of these findings is limited due to poor study methodology. Additionally, it is unclear if this effect is due to cat's claw, other ingredients, or the combination.
• Inflammatory bowel disease (IBD). Although there is interest in using oral cat's claw for ulcerative colitis and Crohn disease, there is insufficient reliable information about the clinical effects of cat's claw for these conditions.
• Osteoarthritis. It is unclear if oral cat's claw is beneficial for osteoarthritis. Details: A small clinical trial shows that taking a specific freeze-dried cat's claw (Uncaria guianensis) extract 100 mg daily orally relieves knee pain related to physical activity within one week of treatment, but does not decrease pain at rest or knee swelling (7317). Other clinical research shows that taking a specific combination supplement (Reparagen) 1800 mg twice daily for 8 weeks can reduce pain and stiffness, improve function, and reduce the need to use rescue medication similarly to glucosamine sulfate. This specific combination supplement contains cat's claw (Vincaria) 300 mg and maca (RNI 249) 1500 mg per dose (33614). It is unclear if this effect is due to cat's claw, maca, or the combination. Additionally, it is unclear how these outcomes compare to the use of placebo.
• Osteoporosis. Although there is interest in using oral cat's claw for osteoporosis, there is insufficient reliable information about the clinical effects of cat's claw for this condition.
• Psoriasis. Oral cat's claw has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research shows that using a specific spray combination of cat's claw (Uncaria tomentosa) 1% and Rhealba oat plantlet extract 0.25% (Pierre Fabre Dermo Cosmetique) up to 6 times daily for 22 days subjectively reduces skin symptoms of psoriasis when compared with baseline (103170). The validity of this finding is limited by the lack of a comparator group. Additionally, it is not clear whether the results are due to cat's claw, oat extract, spray excipients, or the combination.
• Rheumatoid arthritis (RA). It is unclear if oral cat's claw is beneficial for RA. Details: A small clinical trial shows that taking a specific cat's claw (Uncaria tomentosa) extract 20 mg three times daily orally, containing 14.7 mg/gram pentacyclic oxindole alkaloids and no tetracyclic oxindole alkaloids, appears to modestly improve symptoms of RA. When taken orally in combination with sulfasalazine or hydroxychloroquine for 24 weeks, cat's claw seems to reduce the number of painful joints when compared with placebo. However, there is no effect on the number of swollen joints, pain, or the patient assessment of disease (8661). More evidence is needed to rate cat's claw for these uses.

(Read more about CAT'S CLAW)

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Acne. Although there has been interest in using topical grapefruit oil for acne, there is insufficient reliable information about the clinical effects of grapefruit for this purpose.
• Asthma. It is unclear if oral grapefruit is beneficial in patients with asthma. Details: There is some evidence that consumption of vitamin C-rich citrus fruits, including grapefruit and others, might improve lung function in people with asthma. Intake of citrus fruits 1-2 times weekly has produced this benefit in some studies (6049,6055,6056). However, other studies have shown no benefit (6057,6058).
• Atherosclerosis. Although there has been interest in using oral grapefruit to treat or prevent atherosclerosis, there is insufficient reliable information about the clinical effects of grapefruit for this purpose.
• Atopic dermatitis (eczema). It is unclear if oral grapefruit seed extract is beneficial in patients with atopic dermatitis. Details: One small, uncontrolled clinical study in patients with atopic dermatitis shows that taking a specific grapefruit seed extract product (ParaMicrocidin, Allergy Research Group) 150 mg three times daily for one month can decrease complaints of constipation, flatulence, and abdominal discomfort, possibly due to changes in intestinal microflora (5866). The validity of these findings is limited by a lack of control group.
• Depression. Although there has been interest in using inhaled grapefruit oil as aromatherapy for depression, there is insufficient reliable information about the clinical effects of grapefruit oil for this purpose.
• Gingivitis. Although there has been interest in using topical grapefruit oil as a rinse for gingivitis, there is insufficient reliable information about the clinical effects of grapefruit oil for this purpose.
• Headache. Although there has been interest in using inhaled grapefruit oil as aromatherapy for headache, there is insufficient reliable information about the clinical effects of grapefruit oil for this purpose.
• Hypercholesterolemia. It is unclear if oral grapefruit is beneficial in patients with hypercholesterolemia. Details: One small clinical study in patients with hypercholesterolemia shows that taking capsules containing grapefruit pectin 5 grams three times daily for 16 weeks decreases total cholesterol by 8% and the ratio of low-density lipoprotein (LDL) to high-density lipoprotein (HDL) cholesterol by 10% when compared to baseline (2216). The validity of these findings is limited by the lack of a comparator group.
• Hypertriglyceridemia. It is unclear if oral grapefruit is beneficial in patients with hypertriglyceridemia. Details: One small clinical study in patients with hypertriglyceridemia that is not well controlled on statin therapy shows that consuming one red or white grapefruit daily for 30 days reduces total cholesterol by 8% to 15.5% and low-density lipoprotein (LDL) cholesterol by 11% to 20% when compared with placebo. In addition, consuming one red, but not one white, grapefruit daily reduces triglyceride levels by 17% when compared with placebo in these patients (53352).
• Intestinal parasite infection. Although there has been interest in using oral grapefruit seed extract for intestinal parasite infections, there is insufficient reliable information about the clinical effects of grapefruit for this purpose.
• Lice. It is unclear if topical grapefruit extract is beneficial in children with head lice. Details: One small clinical study in children aged 2-9 years with head lice shows that applying 50 mL of a specific shampoo containing grapefruit extract (Licatack shampoo) to the hair for 10-20 minutes and then rinsing with water and combing can eliminate adult lice. Applying a second application after 10 days seems to help remove any remaining nits (91417). The validity of these findings is limited by a lack of control group.
• Obesity. While some small studies suggest that oral grapefruit extract, taken in combination with other citrus extracts, may modestly improve weight loss, the effect of oral grapefruit alone is unclear. Details: One small clinical study in obese adults shows that consuming one and a half fresh grapefruits daily for 12 weeks reduces body weight by 1.3 kg when compared with placebo. Also, although drinking 8 ounces of grapefruit juice or taking grapefruit capsules three times daily for 12 weeks did not improve body weight when compared with placebo in the overall study population, a sub-group analysis of obese adults with metabolic syndrome shows that taking grapefruit capsules or drinking grapefruit juice increases weight loss and improves insulin resistance when compared with placebo (53353). Grapefruit has also been evaluated in combination with other citrus ingredients. Two clinical studies shows that taking a specific combination product (Sinetrol, Fytexia) containing sweet orange, blood orange, and grapefruit extracts for 12 weeks can decrease body weight, body fat percentage, and body mass index (BMI) in otherwise healthy overweight adults (95517,95518). In one study, taking this supplement as 450 mg twice daily for 12 weeks reduced body weight by 1 kg and body fat percentage by 6.5% when compared with placebo. Hip circumference, waist circumference, and blood glucose were also reduced when compared with placebo (95518). In another study, taking this same supplement as 700 mg twice daily for 12 weeks reduced body weight by 5.6 kg, body fat percentage by 5%, and BMI by 2% when compared to baseline. Patients taking placebo experienced no significant improvements from baseline (95517). It is not clear if these effects are due to grapefruit extract, other ingredients, or the combination.
• Pharyngitis. Although there has been interest in using topical grapefruit oil as a gargle for pharyngitis, there is insufficient reliable information about the clinical effects of grapefruit oil for this purpose.
• Psoriasis. Although there has been interest in using oral grapefruit for psoriasis, there is insufficient reliable information about the clinical effects of grapefruit for this purpose.
• Stress. Although there has been interest in using inhaled grapefruit oil as aromatherapy for stress, there is insufficient reliable information about the clinical effects of grapefruit oil for this purpose.
• Upper respiratory tract infection (URTI). Although there has been interest in using grapefruit oil as aromatherapy for various upper respiratory tract infections, including influenza and the common cold, there is insufficient reliable information about the clinical effects of grapefruit oil for these conditions.
• Vaginal candidiasis. Although there has been interest in using oral and topical grapefruit seed extract for vaginal candidiasis, there is insufficient reliable information about the clinical effects of grapefruit seed extract for this purpose. More evidence is needed to rate grapefruit for these uses.

(Read more about GRAPEFRUIT)

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Dyspepsia. Oral olive leaf extract has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small study in healthy adults shows that taking a specific combination product containing olive leaf extract 24% and prickly pear cactus 33% (Mucosave, Bionap S.R.L.) 400 mg daily for 8 weeks seems to improve dyspepsia and other gastrointestinal symptoms when compared with placebo (105904). It is unclear if this benefit would occur in patients with clinically diagnosed dyspepsia.
• Exercise-induced respiratory infections. It is unclear if oral olive leaf extract is beneficial for reducing respiratory infections from exercise. Details: A small clinical study in high school athletes shows that taking one tablet of olive leaf extract providing eleuropein 100 mg daily for 2 months during training season does not reduce the incidence of the common cold when compared with placebo. While it may reduce the number of sick days by 28%, a sub-group analysis suggests that this reduction is only evident in female athletes (101860).
• Gastroesophageal reflux disease (GERD). Although there is interest in using oral olive leaf for GERD, there is insufficient reliable information about the clinical effects of olive for this condition.
• Herpes zoster (shingles). Although there is interest in using oral olive leaf for shingles, there is insufficient reliable information about the clinical effects of olive for this condition.
• Influenza. Although there is interest in using oral olive leaf for influenza, there is insufficient reliable information about the clinical effects of olive for this condition.
• Metabolic syndrome. It is unclear if oral olive leaf extract is beneficial for improving body composition and cardiovascular risk factors in patients with metabolic syndrome. Details: A small clinical trial in overweight, middle-aged males at risk for metabolic syndrome shows that taking four capsules of olive leaf extract providing oleuropein 51.1 mg and hydroxytyrosol 9.7 mg daily for 12 weeks improves insulin sensitivity by 15% when compared with placebo. However, body composition, blood pressure, cholesterol levels, and other cardiovascular risk factors were not improved (92245).
• Osteoarthritis. It is unclear if oral olive fruit or leaf extract is beneficial for improving osteoarthritis. Details: Preliminary clinical research shows that taking a freeze-dried aqueous extract of olive fruit 400 mg daily for 8 weeks decreases pain and increases mobility in people with osteoarthritis (14844). Other preliminary clinical research in adults with knee osteoarthritis shows that taking olive leaf extract 50.1 mg daily for 4 weeks improves overall pain measurements by 14%, compared to only 4% in the placebo group. However, many individual measurements of pain are not improved (92252).
• Osteoporosis. It is unclear if oral olive leaf extract is beneficial for osteoporosis. Details: Clinical research shows that taking olive leaf extract (Bonolive, BioActor BV) 250 mg daily for 12 months, along with elemental calcium 400 mg daily, increases osteocalcin levels by about 32% when compared to baseline; this increase was significant when compared to those taking calcium 400 mg plus placebo, who showed a 6% decrease in osteocalcin levels. However, taking olive leaf extract does not significantly increase bone mineral density of the lumbar spine or femur neck when compared with placebo (92247).
• Rheumatoid arthritis (RA). It is unclear if oral olive fruit extract is beneficial for improving RA symptoms. Details: Preliminary clinical research in adults with RA shows that taking an aqueous freeze-dried extract of olive fruit 400 mg daily for 8 weeks does not improve symptoms when compared with control (14844). More evidence is needed to rate the effectiveness of olive for these uses.

(Read more about OLIVE)

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Acne. Although there has been interest in using topical oregano oil for acne, there is insufficient reliable information about the clinical effects of oregano for this purpose.
• Asthma. Although there has been interest in using oral oregano for asthma, there is insufficient reliable information about the clinical effects of oregano for this purpose.
• Bronchitis. Although there has been interest in using oral oregano for bronchitis, there is insufficient reliable information about the clinical effects of oregano for this purpose.
• Canker sores. Although there has been interest in using topical oregano oil for canker sores, there is insufficient reliable information about the clinical effects of oregano for this purpose.
• Cough. Although there has been interest in using oral oregano for cough, there is insufficient reliable information about the clinical effects of oregano for this purpose.
• Dandruff. Although there has been interest in using topical oregano oil for dandruff, there is insufficient reliable information about the clinical effects of oregano for this purpose.
• Diabetes. Although there has been interest in using oral oregano for diabetes, there is insufficient reliable information about the clinical effects of oregano for this purpose.
• Dysmenorrhea. Although there has been interest in using oral oregano for dysmenorrhea, there is insufficient reliable information about the clinical effects of oregano for this purpose.
• Dyspepsia. Although there has been interest in using oral oregano for dyspepsia, there is insufficient reliable information about the clinical effects of oregano for this purpose.
• Gingivitis. Although there has been interest in using topical oregano oil for gingivitis, there is insufficient reliable information about the clinical effects of oregano for this purpose.
• Headache. Although there has been interest in using topical oregano oil for headache, there is insufficient reliable information about the clinical effects of oregano for this purpose.
• Insect repellent. Although there has been interest in using topical oregano oil as an insect repellent, there is insufficient reliable information about the clinical effects of oregano for this purpose.
• Intestinal parasite infection. It is unclear if oral oregano is beneficial in patients with intestinal parasite infections. Details: In one small, uncontrolled study, taking a specific emulsified oregano leaf oil product (ADP, Biotics Research Corporation) 200 mg orally three times daily with meals for 6 weeks resulted in eradication of Blastocystis hominis, Entamoeba hartmanni, and Endolimax nana from the stool in 10 of 13 patients (6878). The clinical significance of this is unclear since the Centers for Disease Control (CDC) considers Entamoeba hartmanni and Endolimax nana to be non-pathogenic, while blastocystosis caused by Blastocystis hominis is usually self-limiting and does not require treatment.
• Pain (acute). Although there has been interest in using topical oregano oil for the relief of acute pain, including joint and muscle pain, there is insufficient reliable information about the clinical effects of oregano for this purpose.
• Psoriasis. Although there has been interest in using topical oregano oil for psoriasis, there is insufficient reliable information about the clinical effects of oregano for this purpose.
• Rhinosinusitis. Although there has been interest in using oral oregano for rhinosinusitis, there is insufficient reliable information about the clinical effects of oregano for this purpose.
• Seborrheic dermatitis. Although there has been interest in using topical oregano oil for seborrheic dermatitis, there is insufficient reliable information about the clinical effects of oregano for this purpose.
• Tinea capitis. Although there has been interest in using topical oregano oil for tinea capitis, there is insufficient reliable information about the clinical effects of oregano for this purpose.
• Tinea corporis. Although there has been interest in using topical oregano oil for tinea corporis, there is insufficient reliable information about the clinical effects of oregano for this purpose.
• Tinea pedis. Although there has been interest in using topical oregano oil for tinea pedis, there is insufficient reliable information about the clinical effects of oregano for this purpose.
• Toothache. Although there has been interest in using topical oregano oil for toothache, there is insufficient reliable information about the clinical effects of oregano for this purpose.
• Upper respiratory tract infection (URTI). Although there has been interest in using oral oregano for URTIs, such as the common cold and influenza, there is insufficient reliable information about the clinical effects of oregano for this purpose.
• Urinary tract infections (UTIs). Although there has been interest in using oral oregano for UTIs, there is insufficient reliable information about the clinical effects of oregano for this purpose.
• Varicose veins. Although there has been interest in using topical oregano oil for varicose veins, there is insufficient reliable information about the clinical effects of oregano for this purpose.
• Warts. Although there has been interest in using topical oregano oil for warts, there is insufficient reliable information about the clinical effects of oregano for this purpose.
• Wound healing. It is unclear if topical oregano is beneficial for improving healing or preventing infections in people with skin wounds. Details: One small clinical trial shows that applying an ointment containing a 3% concentration of the water-soluble fraction of the oregano plant twice daily for 10-14 days after minor dermatological surgery might reduce infection rates and improve scar formation when compared with petrolatum ointment (67348). More evidence is needed to rate oregano for these uses.

(Read more about OREGANO)

POSSIBLY SAFE ...when used orally, short-term. A specific freeze-dried aqueous extract seems to be safe when used in doses of 100 mg daily for up to four weeks (7317). Another extract of cat's claw, free of tetracyclic oxindole alkaloids, seems to be safe when used in doses of 60 mg daily for up to 24 weeks (8661). There is insufficient reliable information available about the safety of cat's claw when used topically.

PREGNANCY: POSSIBLY UNSAFE
when used orally. There is concern that cat's claw might be unsafe based on its traditional use as a contraceptive (12); avoid using.

LACTATION:
Insufficient reliable information available; avoid using.

(Read more about CAT'S CLAW)

LIKELY SAFE ...when used orally in amounts commonly found in foods. Grapefruit has Generally Recognized as Safe status (GRAS) in the US (4912).

POSSIBLY SAFE ...when used orally and appropriately for medicinal purposes. A grapefruit seed extract has been safely used in clinical research (5866). In addition, capsules containing grapefruit pectin 15 grams daily have been used in clinical research for up to 16 weeks (2216).

POSSIBLY UNSAFE ...when used orally in excessive amounts. Preliminary population research shows that consuming a quarter or more of a whole grapefruit daily is associated with a 25% to 30% increased risk of postmenopausal breast cancer (14858). Grapefruit juice is thought to reduce estrogen metabolism resulting in increased endogenous estrogen levels. More evidence is needed to validate this finding.

PREGNANCY AND LACTATION:
There is insufficient reliable information available about the safety of using medicinal amounts of grapefruit during pregnancy and lactation; avoid using.

(Read more about GRAPEFRUIT)

LIKELY SAFE ...when olive fruit is used orally and appropriately in amounts commonly found in foods.

POSSIBLY SAFE ...when olive leaf extract is used orally and appropriately. Olive leaf extract providing 51-100 mg oleuropein daily has been used with apparent safety for 6-8 weeks (92245,92247,101860). There is insufficient reliable information available about the safety of olive fruit extract when used in amounts greater than those found in foods.

PREGNANCY AND LACTATION:
Insufficient reliable information available; stick with amounts commonly found in foods.

(Read more about OLIVE)

LIKELY SAFE ...when used orally in amounts commonly found in foods. Oregano leaf and oil have Generally Recognized as Safe (GRAS) status in the US (4912). There is insufficient reliable information available about the safety of oregano when used orally in amounts greater than those found in food. There is also insufficient reliable information available about the safety of oregano when used topically. Oregano oil in concentrations of greater than 1% may be irritating when applied to mucous membranes (67348,88188).

PREGNANCY: POSSIBLY UNSAFE
when used orally in medicinal amounts. Oregano is thought to have abortifacient and emmenagogue effects (19,7122,19104).

LACTATION:
There is insufficient reliable information available about the safety of oregano when used in medicinal amounts; avoid amounts greater than those found in food.

(Read more about OREGANO)

ANTICOAGULANT/ANTIPLATELET DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, cat's claw may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.  Details Cat's claw contains rhynchophylline and isorhynchophylline. Animal research suggests that these alkaloids can inhibit platelet aggregation (40220,40276). This interaction has not been reported in humans.

ANTIHYPERTENSIVE DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = D Theoretically, taking cat's claw with antihypertensive drugs might increase the risk of hypotension.  Details Cat's claw contains rhynchophylline. In vitro and animal research suggests that rhynchophylline can lower blood pressure (40255,40268,40276). This interaction has not been reported in humans.

CALCIUM CHANNEL BLOCKERS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = D Theoretically, taking cat's claw with calcium channel blockers might increase the risk of hypotension.  Details Cat's claw contains various alkaloids, including rhynchophylline, isorhynchophylline, corynoxeine, and isocorynoxiene. Animal research suggests that these alkaloids can lower blood pressure by acting as calcium channel blockers (40255,40268). This interaction has not been reported in humans.

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, cat's claw might increase the levels and adverse effects of drugs metabolized by CYP3A4.  Details In vitro research shows that cat's claw can inhibit CYP3A4 enzymes (6450,25522). In one case report, a patient taking cat's claw (at an unspecified dose) experienced increased serum levels of atazanavir, ritonavir, and saquinavir, all of which are CYP3A4 substrates. Levels returned to normal 15 days after discontinuation of the cat's claw supplement, suggesting inhibition of CYP3A4 by cat's claw (25522).

(Read more about CAT'S CLAW)

ACEBUTOLOL (Sectral) Interaction Rating = Minor Be watchful with this combination. Severity = Insignificant •  Occurrence = Possible •  Level of Evidence = B Grapefruit juice can decrease blood levels of acebutolol, potentially decreasing the clinical effects of acebutolol.  Details Clinical research shows that grapefruit juice can modestly decrease acebutolol levels by 7% and reduce peak plasma concentration by 19% by inhibiting organic anion transporting polypeptide (OATP) (17603,18101). The acebutolol half-life is also extended by 1.1 hours when grapefruit juice is consumed concomitantly (18101). Grapefruit juice is thought to affect OATP for only a short time. Therefore, separating drug administration and consumption of grapefruit by at least 4 hours is likely to prevent this interaction (17603,17604).

ALISKIREN (Tekturna, Rasilez) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Grapefruit juice can decrease blood levels of aliskiren, potentially decreasing the clinical effects of aliskiren.  Details Clinical research shows that grapefruit juice can decrease aliskiren levels by approximately 60% by inhibiting organic anion transporting polypeptide (OATP) (91428). Grapefruit juice is thought to affect OATP for only a short time. Therefore, separating drug administration and consumption of grapefruit by at least 4 hours is likely to prevent this interaction (17603,17604).

AMIODARONE (Cordarone) Interaction Rating = Major Do not take this combination. Severity = High •  Occurrence = Probable •  Level of Evidence = B Grapefruit juice can increase blood levels of amiodarone, potentially increasing the effects and adverse effects of amiodarone.  Details Clinical research shows that grapefruit juice inhibits metabolism and increases absorption of amiodarone. Grapefruit juice increases amiodarone plasma levels by 50% and peak concentration by 84% (17601,17672,22120).

AMPRENAVIR (Agenerase) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = B Grapefruit juice might decrease blood levels of amprenavir, although this is not likely to be clinically significant.  Details Some clinical research shows that grapefruit juice can slightly decrease amprenavir levels (17673); however, this is probably not clinically significant.

ARTEMETHER (Artenam, Paluther) Interaction Rating = Major Do not take this combination. Severity = Moderate •  Occurrence = Likely •  Level of Evidence = B Grapefruit juice can increase blood levels of oral artemether, potentially increasing the effects and adverse effects of artemether.  Details Clinical research shows that grapefruit juice increases the levels of oral artemether by 90% to 250% in healthy males (5065,5066).

BENZODIAZEPINES Interaction Rating = Major Do not take this combination. Severity = High •  Occurrence = Likely •  Level of Evidence = B Grapefruit juice might increase blood levels of some oral benzodiazepines, potentially increasing the effects and adverse effects of these drugs.  Details Clinical research shows that grapefruit juice can increase plasma triazolam concentrations. Repeated consumption of grapefruit juice greatly increases triazolam concentrations and prolongs the half-life, probably due to inhibition of cytochrome P450 3A4 (CYP3A4) (7776,22118,22131,22133). Some studies show that grapefruit juice, particularly when taken in large quantities, reduces the clearance and increases the maximum blood levels, area under the plasma concentration curve (AUC), and duration of effect of midazolam. However, there is no effect on intravenous midazolam (4300,10159,11275,17601,22117,22119,16711,91427,95978). Grapefruit juice has also been shown to increase the maximum blood levels and duration of effect of diazepam, but the clinical significance of this is not known (3228). This interaction does not appear to occur with alprazolam (17674).

BLONANSERIN (Lonasen) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Grapefruit juice can increase blood levels of blonanserin, potentially increasing the effects and adverse effects of blonanserin.  Details Blonanserin is metabolized primarily by cytochrome P450 3A4 (CYP3A4). A small clinical study shows that taking grapefruit juice along with oral blonanserin increases exposure to blonanserin almost 6-fold due to inhibition of intestinal CYP3A4 by grapefruit juice and prolongs the elimination half-life of blonanserin by 2.2-fold due to inhibition of hepatic CYP3A4 by grapefruit juice (96943).

BUDESONIDE (Entocort, UCERIS) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Grapefruit juice can increase blood levels of budesonide, potentially increasing the effects and adverse effects of budesonide.  Details Budesonide is metabolized by cytochrome P450 3A4 (CYP3A4). A small clinical study shows that taking grapefruit juice along with oral budesonide increases the plasma concentration of budesonide. This effect is attributed to grapefruit-induced inhibition of CYP3A4 in both the colon and small intestine (91425).

BUSPIRONE (BuSpar) Interaction Rating = Major Do not take this combination. Severity = Moderate •  Occurrence = Likely •  Level of Evidence = B Grapefruit juice can increase blood levels of buspirone, potentially increasing the effects and adverse effects of buspirone.  Details Clinical research shows that grapefruit juice increases absorption and plasma concentrations of buspirone (3771).

CAFFEINE Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = D Grapefruit juice can decrease the clearance of caffeine, potentially increasing the effects and adverse effects of caffeine.  Details Clinical research shows that grapefruit juice decreases caffeine clearance (4300).

CALCIUM CHANNEL BLOCKERS Interaction Rating = Major Do not take this combination. Severity = Moderate •  Occurrence = Likely •  Level of Evidence = B Grapefruit juice can increase blood levels of oral calcium channel blockers, potentially increasing the effects and adverse effects of these drugs.  Details Clinical research shows that grapefruit juice increases absorption and plasma concentrations of amlodipine (523), nifedipine (528,22114), nisoldipine (529), verapamil (7779,8285), felodipine, nimodipine, nicardipine, diltiazem, pranidipine, nitrendipine, and manidipine (524,528,1388,4300,7780,11276,22136,53338,22138,22139) (22140,22141,22142,22143,22147,22148,22149,53367,22158), This interaction is likely the result of the inhibition of intestinal metabolism of these drugs by CYP3A4 (7779,7780), although some research suggests grapefruit may alter plasma drug levels by reducing the rate of gastric emptying (22167). Consuming grapefruit juice 1 liter daily increases steady state concentrations of verapamil by as much as 50% (8285). However, some references dispute the clinical relevance of the interactions with amlodipine, diltiazem, and verapamil (3230,4300,22159). Other research in healthy individuals suggests plasma levels of felodipine and nifedipine are not affected when given intravenously (22144,22146). There is considerable interindividual variability in the effect of grapefruit juice on drug metabolism, which might account for inconsistent study results (7777,7779,8285). In healthy older adults, the hemodynamic response to felodipine plus grapefruit juice might be influenced by altered autonomic regulation. In older healthy adults, a single dose of grapefruit juice and felodipine enhanced the blood pressure-lowering effects of felodipine. However, after a week of grapefruit juice and felodipine (steady state), the hypotensive activity was reduced, possibly due to compensatory tachycardia (1392). Research indicates it is necessary to withhold grapefruit juice for as long as 3 days to avoid interactions with felodipine and nisoldipine (5068,5069,6453,22145).

CARBAMAZEPINE (Tegretol) Interaction Rating = Major Do not take this combination. Severity = High •  Occurrence = Likely •  Level of Evidence = B Grapefruit juice can increase blood levels of carbamazepine, potentially increasing the effects and adverse effects of carbamazepine.  Details Clinical research shows that grapefruit juice increases absorption and plasma concentrations of carbamazepine (524).

CARVEDILOL (Coreg) Interaction Rating = Major Do not take this combination. Severity = Moderate •  Occurrence = Likely •  Level of Evidence = B Grapefruit juice can increase blood levels of carvedilol, potentially increasing the effects and adverse effects of carvedilol.  Details Clinical research shows that grapefruit juice increases the bioavailability of a single dose of carvedilol by 16% (5071).

CELIPROLOL (Celicard) Interaction Rating = Major Do not take this combination. Severity = High •  Occurrence = Probable •  Level of Evidence = B Grapefruit juice can decrease blood levels of celiprolol, potentially decreasing the clinical effects of celiprolol.  Details In human research, taking grapefruit juice within two hours of celiprolol appears to decrease absorption and blood levels of celiprolol by approximately 85% (91421). This interaction is due to grapefruit-induced inhibition of organic anion transporting polypeptide (OATP) (17603,17604,22161). Grapefruit juice is thought to affect OATP for only a short time. Therefore, separating drug administration and consumption of grapefruit by at least 4 hours is likely to prevent this interaction (17603,17604).

CISAPRIDE (Propulsid) Interaction Rating = Major Do not take this combination. Severity = High •  Occurrence = Likely •  Level of Evidence = B Grapefruit juice can increase blood levels of cisapride, potentially increasing the effects and adverse effects of cisapride.  Details Clinical research shows that grapefruit juice increases the absorption and plasma concentrations of cisapride. According to the cisapride prescribing information, grapefruit juice is contraindicated in patients taking cisapride (1383,3226,17601,22164,22165).

CLOMIPRAMINE (Anafranil) Interaction Rating = Major Do not take this combination. Severity = High •  Occurrence = Probable •  Level of Evidence = D Theoretically, grapefruit juice might increase blood levels of clomipramine, potentially increasing the effects and adverse effects of clomipramine.  Details Case reports have shown that clomipramine trough levels increase significantly after the addition of grapefruit juice to the therapeutic regimen (5064).

CLOPIDOGREL (Plavix) Interaction Rating = Major Do not take this combination. Severity = High •  Occurrence = Probable •  Level of Evidence = B Grapefruit juice can decrease blood levels of the active metabolite of clopidogrel, thereby decreasing the antiplatelet effect of clopidogrel.  Details Clopidogrel is an antiplatelet prodrug that is metabolized primarily by cytochrome P450 2C19 (CYP2C19) to form the active metabolite. A small clinical study shows that taking grapefruit juice with clopidogrel decreases plasma levels of the active metabolite by more than 80% and impairs the antiplatelet effect of clopidogrel. This effect is possibly due to grapefruit-induced inhibition of CYP2C19 (91419).

COLCHICINE Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = B Theoretically, grapefruit juice might increase blood levels of colchicine, potentially increasing the effects and adverse effects of colchicine.  Details Colchicine is an alkaloid that undergoes P-glycoprotein (P-gp) mediated drug efflux in the intestines, followed by metabolism by cytochrome P450 3A4 (CYP3A4). There is concern that grapefruit juice will increase the effects and adverse effects of colchicine due to grapefruit-induced inhibition of P-gp and/or CYP3A4. In vitro evidence shows that grapefruit juice increases absorption of colchicine by inhibiting P-gp (94158). A case of acute colchicine toxicity has been reported for an 8-year-old female who drank grapefruit juice while taking high-dose colchicine, long-term (94157). However, one small clinical study in healthy adults shows that drinking grapefruit juice 240 mL twice daily for 4 days does not affect the bioavailability or adverse effects of a single dose of colchicine 0.6 mg taken on the fourth day (35762).

CYCLOSPORINE (Neoral, Sandimmune) Interaction Rating = Major Do not take this combination. Severity = Moderate •  Occurrence = Likely •  Level of Evidence = B Grapefruit juice can increase blood levels of oral cyclosporine, potentially increasing the effects and adverse effects of cyclosporine.  Details Clinical research shows that grapefruit juice increases the absorption and plasma concentrations of cyclosporine (522,11270,22113,22150,22152,22153,22154,22155). The mechanism of action is unclear. However, there is no effect on intravenous cyclosporine (22151).

CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, grapefruit juice might increase levels of drugs metabolized by CYP1A2.  Details In vitro research suggests that grapefruit juice might inhibit CYP1A2 enzymes (12479). So far, 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 = B Theoretically, grapefruit juice might increase levels of drugs metabolized by CYP2C19.  Details In vitro research suggests that grapefruit juice might inhibit CYP2C19 enzymes (12479). Also, a small clinical study shows that taking grapefruit juice with clopidogrel, an antiplatelet prodrug that is metabolized primarily by CYP2C19, decreases plasma levels of the active metabolite and impairs the antiplatelet effect of clopidogrel. This effect is likely due to grapefruit-induced inhibition of CYP2C19 (91419).

CYTOCHROME P450 2C9 (CYP2C9) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, grapefruit juice might increase levels of drugs metabolized by CYP2C9.  Details In vitro research suggests that grapefruit juice might inhibit CYP2C9 enzymes (12479). So far, this interaction has not been reported in humans.

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES Interaction Rating = Major Do not take this combination. Severity = Moderate •  Occurrence = Likely •  Level of Evidence = B Grapefruit juice can increase levels of drugs metabolized by CYP3A4.  Details Clinical research shows that grapefruit juice can inhibit CYP3A4 metabolism of drugs, causing increased drug levels and potentially increasing the risk of adverse effects (3227,3774,8283,8285,8286,22129,91427,104190). When taken orally, effects of grapefruit juice on CYP3A4 levels appear to last at least 48 hours (91427). Grapefruit's ability to inhibit CYP3A4 has even been harnessed to intentionally increase levels of venetoclax, which is metabolized by CYP3A4, in an elderly patient with acute myeloid leukemia who could not afford full dose venetoclax. The lower dose of venetoclax in combination with grapefruit juice resulted in serum levels of venetoclax in the therapeutic reference range of full dose venetoclax and positive treatment outcomes for the patient (112287). Professional consensus recommends the consideration of patient age, existing medical conditions, additional medications, and the potential for additive adverse effects when evaluating the risks of concomitant use of grapefruit juice with any medication metabolized by CYP3A4. While all patients are at risk for interactions with grapefruit juice consumption, patients older than 70 years of age and those taking multiple medications are at the greatest risk for a serious or fatal interaction with grapefruit juice (95970,95972).

DAPOXETINE (Priligy) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Grapefruit juice can increase blood levels of dapoxetine, potentially increasing the effects and adverse effects of dapoxetine.  Details Pharmacokinetic research shows that drinking grapefruit juice 250 mL prior to taking dapoxetine 60 mg can increase the maximum plasma concentration of dapoxetine by 80% and prolong the elimination half-life by 43%. This effect is attributed to the inhibition of both intestinal and hepatic cytochrome P450 3A4 (CYP3A4) by grapefruit (95975).

DEXTROMETHORPHAN (Robitussin DM, others) Interaction Rating = Major Do not take this combination. Severity = High •  Occurrence = Probable •  Level of Evidence = B Grapefruit juice can increase blood levels of dextromethorphan, potentially increasing the effects and adverse effects of dextromethorphan.  Details Clinical research shows that grapefruit juice can inhibit cytochrome P450 3A4 (CYP3A4) metabolism, causing increased dextromethorphan levels (11362).

ERYTHROMYCIN Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Grapefruit juice can increase blood levels of erythromycin, potentially increasing the effects and adverse effects of erythromycin.  Details Clinical research shows that concomitant use of erythromycin with grapefruit can inhibit cytochrome P450 3A4 (CYP3A4) metabolism of erythromycin, increasing plasma concentrations of erythromycin by 35% (8286).

ESTROGENS Interaction Rating = Major Do not take this combination. Severity = High •  Occurrence = Probable •  Level of Evidence = B Grapefruit juice can increase blood levels of estrogens, potentially increasing the effects and adverse effects of estrogens.  Details Clinical research shows that grapefruit increases the levels of endogenous and exogenous estrogens by inhibiting cytochrome P450 3A4 (CYP3A4) enzymes (525,526,14858). Grapefruit juice increases exogenously administered 17-beta-estradiol by about 20% in females without ovaries and ethinyl-estradiol in healthy females (525,526,22160).

ETOPOSIDE (VePesid) Interaction Rating = Major Do not take this combination. Severity = High •  Occurrence = Probable •  Level of Evidence = B Grapefruit juice can decrease blood levels of etoposide, potentially decreasing the clinical effects of etoposide.  Details Clinical research shows that grapefruit juice decreases the absorption and plasma concentrations of etoposide. There is some evidence that grapefruit juice co-administered with oral etoposide can reduce levels of etoposide by about 26% (8744). Grapefruit juice seems to inhibit organic anion transporting polypeptide (OATP), which is a drug transporter in the gut, liver, and kidney (7046,17603,17604). Grapefruit juice is thought to affect OATP for only a short time. Therefore, separating drug administration and consumption of grapefruit by at least 4 hours is likely to prevent this interaction (17603,17604).

FEXOFENADINE (Allegra) Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Likely •  Level of Evidence = B Grapefruit juice can decrease blood levels of fexofenadine, thereby decreasing the clinical effects of fexofenadine.  Details Clinical research shows that grapefruit juice can significantly decrease oral absorption and blood levels of fexofenadine. In one study, consuming a drink containing grapefruit juice 25% decreased bioavailability of fexofenadine by about 24%. Consuming a full-strength grapefruit juice drink reduced bioavailability by 67% (7046). In another study, consuming grapefruit juice 300 mL decreased fexofenadine levels by 42%. Consuming 1200 mL of grapefruit juice reduced levels by 64% (17602). Similarly, drinking grapefruit juice 240 mL decreased the oral bioavailability of fexofenadine by 25% in another pharmacokinetic study (112288). Fexofenadine manufacturer data indicates that concomitant administration of grapefruit juice and fexofenadine results in larger wheal and flare sizes in research models. This suggests that grapefruit also reduces the clinical response to fexofenadine (17603). Grapefruit juice seems to inhibit organic anion transporting polypeptide (OATP), which is a drug transporter in the gut, liver, and kidney (7046,17603,17604,22161). Grapefruit juice is thought to affect OATP for only a short time. Therefore, separating drug administration and consumption of grapefruit by at least 4 hours is likely to prevent this interaction (17603,17604).

FLUVOXAMINE (Luvox) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Grapefruit juice can increase blood levels of fluvoxamine, potentially increasing the effects and adverse effects of fluvoxamine.  Details Clinical research shows that grapefruit juice inhibits metabolism and increases fluvoxamine levels and peak concentration (17675).

HALOFANTRINE Interaction Rating = Major Do not take this combination. Severity = High •  Occurrence = Probable •  Level of Evidence = B Grapefruit juice can increase blood levels of halofantrine, potentially increasing the effects and adverse effects of halofantrine.  Details Clinical research shows that grapefruit juice inhibits cytochrome P450 3A4 (CYP3A4) metabolism, which increases halofantrine levels and peak concentration, as well as a marker of ventricular tachyarrhythmia potential (22129).

HMG-CoA REDUCTASE INHIBITORS ("Statins") Interaction Rating = Major Do not take this combination. Severity = Moderate •  Occurrence = Likely •  Level of Evidence = B Grapefruit juice can increase blood levels of statins that are metabolized by cytochrome P450 3A4 (CYP3A4), potentially increasing the effects and adverse effects of these statins. Additionally, grapefruit juice might interfere with the bioavailability of statins that are substrates of organic anion transporting polypeptides (OATP).  Details Clinical research shows that grapefruit juice inhibits metabolism and increases absorption and plasma concentrations of statins that are metabolized by CYP3A4. These include lovastatin (527,11274), simvastatin (3774,7782,22127), and atorvastatin (3227,12179,22126). Keep in mind that there is considerable variability in the effect of grapefruit juice on drug metabolism, so individual patient response is difficult to predict (7777,7781). Some statins, including pravastatin, fluvastatin, pitavastatin, and rosuvastatin, are not metabolized by CYP3A4. However, grapefruit juice might still affect the bioavailability of these statins. These statins are substrates of OATP. Grapefruit juice can inhibit OATP. Therefore, grapefruit juice may reduce the bioavailability or increase drug levels of these statins depending on the type of OATP. However, grapefruit juice affects OATP for only a short time. Therefore, separating drug administration by at least 4 hours is likely to avoid this interaction (3227,12179,17601,22126,91420).

ITRACONAZOLE (Sporanox) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Grapefruit juice can interfere with itraconazole absorption, although the clinical significance of this interaction is unclear.  Details Clinical research shows that grapefruit juice can affect itraconazole absorption and might increase or decrease itraconazole levels (310,17601,22123).

LEVOTHYROXINE (Synthroid, others) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Grapefruit juice can decrease blood levels of levothyroxine, potentially decreasing the effectiveness of levothyroxine.  Details Clinical research shows that grapefruit juice modestly decreases levothyroxine levels by 11% by inhibiting organic anion transporting polypeptide (OATP) (17604,22163). Grapefruit juice is thought to affect OATP for only a short time. Therefore, separating drug administration and consumption of grapefruit by at least 4 hours is likely to prevent this interaction (17603,17604).

LOSARTAN (Cozaar) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Grapefruit juice can decrease blood levels of the active metabolite of losartan, potentially decreasing the clinical effects of losartan.  Details Losartan is an inactive prodrug which must be metabolized to its active form, E-3174, to be effective. In one human study, grapefruit juice reduced losartan metabolism, increased losartan AUC, and reduced the AUC of the major active losartan metabolite, E-3174 (1391).

METHADONE (Dolophine) Interaction Rating = Major Do not take this combination. Severity = High •  Occurrence = Probable •  Level of Evidence = B Grapefruit juice can increase blood levels of methadone, potentially increasing the effects and adverse effects of methadone.  Details Clinical research shows that grapefruit juice inhibits the metabolism of methadone, increasing methadone levels and peak concentrations (17676). In one case, a 51-year-old male taking methadone 90 mg daily and no other medications was found unresponsive. The patient reported drinking grapefruit juice 500 mL daily for 3 days prior to the event. Methadone is a substrate of cytochrome P450 3A4 (CYP3A4), and grapefruit juice-induced inhibition of CYP3A4 is the likely cause of this interaction (102056).

METHYLPREDNISOLONE Interaction Rating = Major Do not take this combination. Severity = Moderate •  Occurrence = Likely •  Level of Evidence = B Grapefruit juice can increase blood levels of methylprednisolone, potentially increasing the effects and adverse effects of methylprednisolone.  Details Clinical research shows that grapefruit juice can increase the plasma concentration of orally administered methylprednisolone. Grapefruit juice 200 mL three times daily given with methylprednisolone 16 mg increased methylprednisolone half-life by 35%, peak plasma concentration by 27%, and total area under the curve by 75% (3123).

NADOLOL (Corgard) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Grapefruit juice might decrease blood levels of nadolol, potentially decreasing the clinical effects of nadolol.  Details Nadolol is a substrate of organic anion transporting polypeptide 1A2 (OATP1A2) (17603,17604,22161). Some research shows that grapefruit juice and its constituent naringin can inhibit organic anion transporting polypeptides (OATP), which can reduce the bioavailability of OATP substrates (17603,17604,22161,91427). However, preliminary clinical research shows that grapefruit juice containing a low amount of naringin does not significantly affect levels of nadolol (91422). It is not known if grapefruit juice containing higher amounts of naringin reduces the bioavailability of nadolol.

NILOTINIB (Tasigna) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Grapefruit juice can increase blood levels of nilotinib, potentially increasing the effects and adverse effects of nilotinib.  Details Clinical research shows that grapefruit juice inhibits metabolism and increases absorption of nilotinib. Grapefruit juice increases nilotinib levels by 29% and peak concentration by 60% (17677).

ORGANIC ANION-TRANSPORTING POLYPEPTIDE SUBSTRATES (OATP) Interaction Rating = Major Do not take this combination. Severity = Moderate •  Occurrence = Likely •  Level of Evidence = B Grapefruit juice can decrease levels of drugs that are substrates of OATP.  Details In vitro and clinical research show that consuming grapefruit juice inhibits OATP, which reduces the bioavailability of oral drugs that are substrates of OATP. Various clinical studies have shown reduced absorption of OATP substrates when taken with grapefruit, including fexofenadine, acebutolol, aliskiren, celiprolol, levothyroxine, nadolol, and pitavastatin (17603,17604,18101,22126,22134,22161,22163,91420,91427,91428,112288). Grapefruit juice is thought to affect OATP for only a short time. Therefore, separating drug administration and consumption of grapefruit by at least 4 hours is likely to prevent this interaction (17603,17604).

OXYCODONE (Oxycontin) Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Probable •  Level of Evidence = B Grapefruit juice can increase blood levels of oxycodone, potentially increasing the effects and adverse effects of oxycodone.  Details Oxycodone is metabolized by both cytochrome P450 3A4 (CYP3A4) and cytochrome P450 2D6 (CYP2D6). A small clinical study shows that grapefruit juice can increase plasma levels of oral oxycodone about 1.7-fold by inhibiting CYP3A4. While the analgesic effects of oxycodone do not seem to be affected, taking grapefruit juice along with oxycodone may theoretically increase the adverse effects of oxycodone (91423).

P-GLYCOPROTEIN SUBSTRATES Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = B Grapefruit juice does not seem to affect renal P-glycoprotein (P-gp). Theoretically, it might inhibit intestinal P-gp, but evidence is conflicting.  Details While most in vitro research shows that grapefruit products inhibit P-gp, (1390,11270,11278,11362,95976), research in humans is less clear. Two small clinical studies in healthy adults using digoxin as a probe substrate show that grapefruit juice does not inhibit P-gp in the kidneys (11277,11282). It is unclear whether this applies to intestinal P-gp, for which digoxin is not considered to be a sensitive probe (105568). Grapefruit juice has been shown to reduce levels of fexofenadine (7046,17602,112288), and increase levels of quinidine (5067,22121). However, as both of these drugs are also substrates of other enzymes and transporters, it is unclear what role, if any, intestinal P-gp has in these findings.

PITAVASTATIN (Livalo) Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Likely •  Level of Evidence = B Grapefruit juice can increase blood levels of pitavastatin, potentially increasing the effects and adverse effects of pitavastatin.  Details Pharmacokinetic research shows that taking grapefruit juice with pitavastatin 2-4 mg can increase blood levels of pitavastatin by 13% to 14%. Unlike simvastatin and atorvastatin, pitavastatin is not significantly metabolized by cytochrome P450 3A4 (CYP3A4) enzymes. Grapefruit juice appears to increase levels of pitavastatin by inhibiting its uptake by organic anion transporting polypeptide 1B1 (OATP1B1) into hepatocytes for metabolism and clearance from the body (22126,91420). Grapefruit juice seems to increase levels of pitavastatin to a greater degree in patients homozygous for a specific polymorphism (388A>G) in the OATP1B1 gene compared to those heterozygous for this polymorphism (91420).

PRASUGREL (Effient) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Grapefruit juice can decrease blood levels of the active metabolite of prasugrel, thereby decreasing the antiplatelet effect of prasugrel.  Details Prasugrel is a prodrug that is metabolized by cytochrome P450 3A4 (CYP3A4) into its active metabolite. A small pharmacokinetic study in healthy volunteers shows that drinking grapefruit juice 200 mL three times daily for 4 days and taking a single dose of prasugrel 10 mg with an additional 200 mL of grapefruit juice on day 3, results in a 49% lower peak plasma level and a 26% lower overall plasma exposure to the active metabolite when compared with drinking water. However, despite the reduced exposure, platelet aggregation seems to be reduced by an average of only 5% (105567). The clinical significance of this interaction is unclear.

PRAZIQUANTEL (Biltricide) Interaction Rating = Major Do not take this combination. Severity = High •  Occurrence = Probable •  Level of Evidence = B Grapefruit juice can increase blood levels of praziquantel, potentially increasing the effects and adverse effects of praziquantel.  Details Clinical research shows that grapefruit juice can inhibit cytochrome P450 3A4 (CYP3A4) metabolism of praziquantel. Plasma concentrations of praziquantel can increase by as much as 160% when administered with 250 mL of commercially available grapefruit juice (8282).

PRIMAQUINE Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Grapefruit juice may increase blood levels of primaquine, potentially increasing the effects and adverse effects of primaquine.  Details Clinical research shows that grapefruit juice increases the bioavailability of primaquine by approximately 20% (22130). The clinical significance of this interaction is not clear.

QT INTERVAL-PROLONGING DRUGS Interaction Rating = Major Do not take this combination. Severity = High •  Occurrence = Probable •  Level of Evidence = B Grapefruit or grapefruit juice, especially if consumed in large amounts, can cause additive QT interval prolongation when taken with QT interval-prolonging drugs, potentially increasing the risk of ventricular arrhythmias.  Details Clinical research in healthy volunteers shows that drinking 6 liters of grapefruit juice over 6 hours prolonged the QTc by a peak amount of 14 milliseconds (ms). This prolongation was similar to the QT prolongation caused by the drug moxifloxacin. In individuals with long QT syndrome, a smaller dose of grapefruit juice, 1.5 liters, resulted in a greater peak QTc prolongation of about 30 ms (100249). The effect of smaller quantities of grapefruit juice on the QT interval is unclear.

QUETIAPINE (Seroquel) Interaction Rating = Major Do not take this combination. Severity = High •  Occurrence = Probable •  Level of Evidence = B Grapefruit juice may increase blood levels of quetiapine, increasing the effects and adverse effects of quetiapine.  Details Quetiapine is metabolized by cytochrome P450 3A4 (CYP3A4). Grapefruit can inhibit CYP3A4 (3227,3774,8283,8285,8286,22129,91427,104190). In one case report, a healthy 28-year-old female with bipolar disorder stabilized on quetiapine 800 mg daily presented with quetiapine toxicity considered to be related to consuming a gallon of grapefruit juice over the past 24 hours (108848).

QUINIDINE Interaction Rating = Major Do not take this combination. Severity = High •  Occurrence = Probable •  Level of Evidence = B Grapefruit juice can alter blood levels of quinidine, potentially increasing or decreasing the clinical effects of quinidine.  Details Clinical research shows that grapefruit juice decreases quinidine absorption, clearance, and metabolism, and prolongs the half-life by about 20% (5067,22121).

SAQUINAVIR (Fortovase, Invirase) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Grapefruit juice can increase blood levels of saquinavir, potentially increasing the effects and adverse effects of saquinavir.  Details Clinical research shows that grapefruit juice increases the absorption and plasma concentrations of saquinavir (3773,22132).

SCOPOLAMINE (Transderm Scop) Interaction Rating = Major Do not take this combination. Severity = High •  Occurrence = Probable •  Level of Evidence = B Grapefruit juice can increase blood levels of scopolamine, potentially increasing the effects and adverse effects of scopolamine.  Details Clinical research shows that grapefruit juice can inhibit cytochrome P450 3A4 (CYP3A4) metabolism of scopolamine, increasing its absorption and plasma concentrations. Oral bioavailability of scopolamine can increase by 30% when administered with 150 mL of grapefruit juice (8284).

SERTRALINE (Zoloft) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Grapefruit juice can increase blood levels of sertraline, potentially increasing the effects and adverse effects of sertraline.  Details Clinical research shows that grapefruit juice inhibits the cytochrome P450 3A4 (CYP3A4) metabolism of sertraline, increasing blood levels of sertraline (22122).

SILDENAFIL (Viagra) Interaction Rating = Major Do not take this combination. Severity = High •  Occurrence = Probable •  Level of Evidence = B Grapefruit juice can increase blood levels of sildenafil, potentially increasing the effects and adverse effects of sildenafil.  Details Clinical research shows that grapefruit juice inhibits cytochrome P450 3A4 (CYP3A4) metabolism of sildenafil, increasing its absorption and plasma concentrations. Oral bioavailability of sildenafil can increase by 23% when administered with 500 mL of commercially available grapefruit juice (8283).

SUNITINIB (Sutent) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Unlikely •  Level of Evidence = B Grapefruit juice may slightly increase blood levels of sunitinib, potentially increasing the effects and adverse effects of sunitinib.  Details Sunitinib is metabolized by cytochrome P450 3A4 (CYP3A4). Grapefruit and grapefruit juice can inhibit CYP3A4 and increase levels of some drugs metabolized by this enzyme. One small clinical study shows that drinking 200 mL of grapefruit juice three times daily can increase the bioavailability of sunitinib by 11% (91429). While this effect is unlikely to be clinically significant, patients should use caution when using grapefruit along with sunitinib. Dose adjustments may be necessary.

TACROLIMUS (Prograf) Interaction Rating = Major Do not take this combination. Severity = High •  Occurrence = Likely •  Level of Evidence = B Grapefruit juice can increase blood levels of tacrolimus, potentially increasing the effects and adverse effects of tacrolimus.  Details Clinical research shows that drinking grapefruit juice 200 mL daily while taking tacrolimus 3 mg daily increases the trough blood concentration of tacrolimus by approximately 3-fold in patients with connective tissue diseases (95974). A single case has also reported a 10-fold increase in tacrolimus trough levels after the ingestion of grapefruit juice over 3 days (22122). This effect is attributed to the inhibition of cytochrome P450 3A4 (CYP3A4) by grapefruit (95974).

TADALAFIL (Cialis) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, grapefruit juice might increase blood levels of tadalafil, potentially increasing the effects and adverse effects of tadalafil.  Details Animal research shows that grapefruit juice increases tadalafil serum concentrations and overall exposure, likely through inhibition of cytochrome P450 3A4 enzymes (104189).

TALINOLOL Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Grapefruit juice might decrease blood levels of talinolol, potentially decreasing the clinical effects of talinolol.  Details Clinical research suggests that grapefruit juice reduces talinolol bioavailability, likely by inhibiting intestinal uptake (22135). The clinical significance of this effect is unclear.

TERFENADINE (Seldane) Interaction Rating = Major Do not take this combination. Severity = High •  Occurrence = Probable •  Level of Evidence = B Grapefruit juice can increase blood levels of terfenadine, potentially increasing the effects and adverse effects of terfenadine.  Details Clinical research shows that grapefruit juice increases the absorption and plasma concentrations of terfenadine (530,22124,22125). The mechanism of action is unclear.

THEOPHYLLINE Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Probable •  Level of Evidence = B Grapefruit juice can decrease blood levels of theophylline, potentially decreasing the effectiveness of theophylline.  Details Clinical research shows that grapefruit juice seems to modestly decrease theophylline levels when given concurrently with sustained-release theophylline (11013). The mechanism of this interaction is unknown.

TICAGRELOR (Brilinta) Interaction Rating = Major Do not take this combination. Severity = High •  Occurrence = Probable •  Level of Evidence = B Grapefruit juice can increase blood levels of ticagrelor, thereby increasing the effects and adverse effects of ticagrelor.  Details Ticagrelor is metabolized by cytochrome P450 3A4 (CYP3A4). Grapefruit can inhibit CYP3A4. A small clinical study shows that taking grapefruit juice with ticagrelor increases blood levels of ticagrelor more than two-fold and increases the antiplatelet activity of ticagrelor (91418).

TOLVAPTAN (Samsca) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Grapefruit juice can increase blood levels of tolvaptan, potentially increasing the effects and adverse effects of tolvaptan.  Details Tolvaptan is metabolized by cytochrome P450 3A4 (CYP3A4). Grapefruit can inhibit CYP3A4. A small clinical study shows that grapefruit juice can increase the bioavailability and blood levels of tolvaptan by approximately 1.6-fold for up to 16 hours (91426).

WARFARIN (Coumadin) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, drinking large amounts of grapefruit juice might increase the effects and adverse effects of warfarin.  Details In one case report, a patient experienced significantly increased international normalized ratio (INR) associated with consumption of 50 ounces of grapefruit juice daily (12061). However, smaller amounts of grapefruit juice might not be a problem. In a small clinical trial, consumption of 24 ounces of grapefruit juice daily for one week had no effect on INR in males treated with warfarin (12063).

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ANTICOAGULANT/ANTIPLATELET DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, oregano might increase the risk of bleeding when taken with anticoagulant or antiplatelet drugs.  Details In vitro research shows that aristolochic acid isolated from oregano leaves has antithrombin activity (67164). It has also been reported that oregano oil inhibits arachidonic acid-induced, and ADP-induced, platelet aggregation (49445).

ANTIDIABETES DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, oregano might increase the risk for hypoglycemia when taken with antidiabetes drugs.  Details In vitro and animal research shows that oregano extracts might lower blood glucose levels (67191,67204,110122).

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General ...Orally, cat's claw seems to be well tolerated. Topically, no adverse effects have been reported; however, a thorough safety evaluation has not been conducted.
Serious Adverse Effects (Rare):
Orally: Kidney injury.

Dermatologic ...Orally, itchy skin lesions occurred rarely in one clinical study. As the patients in this study had solid tumors with no further therapeutic options, it cannot be determined if any adverse effects were due to the course of disease or to cat's claw. No placebo was used in the study (92502).

Gastrointestinal ...Orally, cat's claw has been reported to cause nausea, vomiting, abdominal pain, abdominal distention, constipation, epigastric pain, and diarrhea in 2% to 10% of individuals in one clinical study. As the patients in this study had solid tumors with no further therapeutic options, it cannot be determined if any adverse effects were due to the course of disease or to cat's claw. No placebo was used in the study (92502).

Hematologic ...In one clinical study of oral cat's claw, anemia occurred in 12% of patients and leukopenia and thrombocytopenia each occurred in 2% of patients. As the patients in this study had solid tumors with no further therapeutic options, it cannot be determined if any adverse effects were due to the course of disease or to cat's claw. No placebo was used in the study (92502).

Neurologic/CNS ...In one clinical study of oral cat's claw, headache occurred in 2% of patients, fatigue and insomnia each occurred in 4% of patients, and neuropathy occurred in 8% of patients. As the patients in this study had solid tumors with no further therapeutic options, it cannot be determined if any adverse effects were due to the course of disease or to cat's claw. No placebo was used in the study (92502).

Renal ...Several case reports link cat's claw to kidney injury. A patient with systemic lupus erythematosus developed acute kidney failure after taking cat's claw, which improved upon its discontinuation (40279). Another patient with a history of cancer who consumed keto-diet shakes containing cat's claw developed biopsy-confirmed acute interstitial nephritis requiring treatment with prednisone. The patient's serum creatinine normalized three months later after stopping the shake (111737). A separate case cited nephrolithiasis linked to a product containing cat's claw (Digestive Advantage and FlexProtex), likely due to its excipient silica dioxide. The patient's symptoms were reduced after discontinuation (40244).
A clinical study also reported a mild serum creatinine increase in 6% of patients taking oral cat's claw, but causality remains unclear due to the advanced disease states of the participants. No placebo was used in the study (92502).

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General ...Orally, grapefruit and grapefruit juice are generally well tolerated.
Serious Adverse Effects (Rare):
Orally: Allergic reactions in sensitive individuals have been reported. When large quantities are consumed, arrhythmias, mineralocorticoid excess, QT prolongation, and pseudohyperaldosteronism have been reported. There is also some concern for increased breast cancer risk with grapefruit consumption.

Cardiovascular ...Orally, consumption of pink grapefruit juice 1000 mL can cause QT prolongation and cause arrhythmias in healthy patients and worsen arrhythmias in cardiomyopathy patients (13031,91424).

Endocrine ...Orally, high doses of grapefruit juice have been observed to cause pseudohyperaldosteronism and mineralocorticoid excess (53340,53346).

Gastrointestinal ...In a case report, grapefruit juice held against the teeth resulted in enamel and tooth surface loss (53368).

Immunologic ...Orally, grapefruit can cause allergic sensitization characterized by eosinophilic gastroenteritis, urticaria, and generalized pruritus (53351,53360).

Oncologic ...Preliminary population research shows that postmenopausal adults who consume a quarter or more of a whole grapefruit daily have a 25% to 30% increased risk of developing breast cancer (14858). Grapefruit is a potent inhibitor of cytochrome P450 3A4, which metabolizes estrogen. Consuming large amounts of grapefruit might significantly increase endogenous estrogen levels and therefore increase the risk of breast cancer. More evidence is needed to validate these findings. Until more is known, advise patients to consume grapefruit in moderation.

Renal ...In population research, consumption of 240 mL/day of grapefruit juice is associated with an increased risk of kidney stones (4216,53372).

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General ...Orally, olive fruit is well tolerated when used in typical food amounts. Olive leaf extract seems to be well tolerated.
Most Common Adverse Effects:
Orally: Headache and stomach discomfort.

Dermatologic ...Orally, one patient in one clinical trial reported bad skin and acne after using olive leaf extract (101860).

Gastrointestinal ...Orally, three patients in one clinical trial reported stomach ache after using olive leaf extract (101860).

Neurologic/CNS ...Orally, three patients in one clinical trial reported headache after using olive leaf extract (101860).

Psychiatric ...In one case report, a 67-year-old female experienced irritability, anger, a lack of control, and feelings of sadness and negativity after consuming a multi-ingredient product containing olive leaf extract 5 grams, horseradish root, and eyebright daily for 38 days. All psychiatric symptoms disappeared within days of stopping the combined product. It is hypothesized that the hydroxytyrosol component of olive leaf extract contributed to these symptoms due to its chemical similarity to dopamine; however, it is not clear if these symptoms were due to the olive leaf extract or to the other ingredients (96245).

Pulmonary/Respiratory ...Olive tree pollen can cause seasonal respiratory allergy (1543).

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General ...Orally, oregano is well tolerated when used in amounts typically found in foods. There is currently a limited amount of information available about the safety of oregano when used in larger amounts as medicine.
Most Common Adverse Effects:
Orally: Gastrointestinal upset.
Topically: Dermatitis in sensitive individuals.
Serious Adverse Effects (Rare):
Orally: Systemic allergic reactions, including anaphylaxis, in sensitive individuals.

Dermatologic ...Oregano has been reported to cause allergic contact dermatitis (46902). Topically, oregano oil in concentrations of greater than 1% has been reported to cause irritation when applied to mucous membranes (67348,88188).

Gastrointestinal ...Orally, large amounts of oregano can cause gastrointestinal upset. Concentrated, non-emulsified oil of oregano can cause localized irritation of the gastrointestinal tract (6878).

Immunologic ...Systemic allergic reactions have been reported with oregano. A 45-year-old male developed pruritus, respiratory difficulty, hypotension, swelling of the lips and tongue, and facial edema after ingesting pizza seasoned with oregano. He had 2 similar episodes after ingesting foods seasoned with thyme, another member of the Lamiaceae family. He did not react to similar foods without the seasoning, and he had positive skin tests to plants of the Lamiaceae family (3705).

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