L-Lysine 500 mg [Discontinued] by Quest

POSSIBLY EFFECTIVE

• Herpes labialis (cold sores). Most clinical research shows that oral lysine can prevent and treat herpes labialis. The benefits of topical lysine are unclear. Details: Despite one small clinical study that found no benefit (1116), most clinical research shows that taking oral lysine monohydrochloride 1000-1248 mg daily or 1000 mg three times daily reduces the recurrence of herpes labialis infections when compared with placebo (1114,1115,1118,1120,19390,19391). Also, small clinical studies show that taking oral lysine 1000 mg daily in up to two divided doses for up to 12 months or 1000 mg three times daily for 6 months reduces the severity and healing time of herpes labialis infections when compared with placebo (1119,1120). Topical lysine has also been studied in combination with other ingredients. A small, open-label study shows that applying a specific combination product containing lysine and zinc oxide plus 14 other ingredients (Super Lysine Plus +) topically every 2 hours for 11 days seems to decrease symptoms and duration of herpes lesions when compared with baseline (11051). The validity of this finding is limited by the lack of a comparator group. Also, it is unclear if any benefit is due to lysine, other ingredients, or the combination.

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Athletic performance. Although there is interest in using oral lysine for improving athletic performance, there is insufficient reliable information about the clinical effects of lysine for this purpose.
• Canker sores. It is unclear if oral lysine is beneficial in patients with canker sores. Details: Preliminary clinical research shows that taking oral lysine 500 mg daily may be beneficial for preventing canker sores, and taking oral lysine 4000 mg daily may be beneficial for decreasing the duration of canker sores (19390).
• Child growth. Oral lysine has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in children aged 4-9 years old with idiopathic short stature shows that taking a combination oral solution containing lysine, inositol, and vitamin B12 10 mL twice daily along with moderate stretching exercises for 12 months increases height, growth velocity, and serum growth indicators and reduces height standard deviation scores when compared with control. However, the combination product does not impact body mass index or the ratio of bone age to chronological age when compared with control (112280). It is unclear if these findings are due to lysine, other ingredients, or the combination.
• Diabetes. It is unclear if oral lysine is beneficial in patients with diabetes. Details: One small clinical study shows that taking lysine hydrochloride 500 mg twice daily for 2 months does not affect fasting or postprandial blood glucose levels or glycated hemoglobin in patients with type 2 diabetes when compared a calcium phosphate control (19395).
• Diabetic foot ulcers. It is unclear if topical lysine is beneficial in patients with diabetic foot ulcers. Details: A small clinical study in adults with type 2 diabetes and grade 2 diabetic foot ulcers shows that applying topical lysine 15% cream twice daily with standard treatment for 8 weeks improves the rate of wound healing and skin color surrounding the wound, and also reduces ulcer size, depth, margins, undermining, edema, induration, granulation tissue, necrotic tissue amount and type, exudate type and amount, and epithelialization when compared with control (112279). The validity of the findings is limited by a lack of blinding and small sample size.
• Hypertension. Limited clinical research shows that oral lysine can reduce blood pressure in hypertensive patients who have deficient dietary lysine intake. Details: Preliminary clinical research in malnourished people in West Africa with deficient lysine intake shows that taking lysine orally 500 mg twice daily for 16 weeks reduces systolic blood pressure (SBP) when compared with placebo in those with hypertension at baseline. The mean SBP was reduced by 17 mmHg in males and 12 mmHg in females. Lysine supplementation did not affect SBP in people who were normotensive at baseline (104104).
• Hypertriglyceridemia. It is unclear if oral lysine is beneficial for patients with hypertriglyceridemia. Details: Preliminary clinical research shows that taking lysine 1 gram daily for 12 weeks, with or without vitamin B6 50 mg daily, does not affect body weight, triglyceride levels, or blood glucose levels when compared with placebo in males with hypertriglyceridemia. Furthermore, this dose of lysine, taken alone or in combination with vitamin B6, appears to slightly decrease high-density lipoprotein (HDL) cholesterol levels after 12 weeks when compared with placebo (90642).
• Muscle strength. Higher dietary intake of lysine seems to improve muscle strength in young under- or well-nourished males. Details: Preliminary clinical research in young, under- or well-nourished males shows that consuming lysine 80 mg/kg daily in the diet for 8 weeks improves muscle strength of the forearm by approximately 7.5% when compared with a diet containing lysine 25-40 mg/kg daily (90643).
• Pressure ulcers. A small study suggests that topical lysine may be beneficial for pressure ulcers. Details: A small clinical study in hospitalized adults shows that applying a specific cream containing lysine hyaluronate (Lys-HA, Lysial, Fatai-Nyl Srl; Jasper LLC) topically with dressing changes once daily for one week, then once every 2 days for one week, reduces pressure ulcer size when compared with a cream containing sodium hyaluronate. The effect appears to be greater in patients with more advanced (stage 3) ulcers compared to less advanced (stage 1) ulcers (90641).
• Schizophrenia. Large doses of oral lysine seem to improve schizophrenia symptoms in patients taking antipsychotic medications. Details: Clinical research in people with schizophrenia not controlled by risperidone shows that taking L-lysine 2 grams three times daily for 8 weeks improves symptoms by approximately 34% when compared with placebo. Negative and psychopathologic symptoms appear to improve the most (90645). In patients stabilized on antipsychotic medications, preliminary clinical research suggests that taking L-lysine 6 grams once daily for 4 weeks improves positive symptoms of schizophrenia, particularly delusions and suspiciousness/persecution, when compared with baseline. However, this improvement was not significant when compared with placebo (90644).
• Stress. Limited clinical research in economically disadvantaged populations shows that fortifying wheat with lysine may reduce stress and anxiety. Details: Preliminary clinical research shows that consuming wheat that has been fortified with lysine 4.2 grams/kg reduces stress in females and reduces anxiety in males in economically disadvantaged populations that typically consume cereal-based diets when compared with control (19394). More evidence is needed to rate lysine for these uses.

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POSSIBLY SAFE ...when used orally in doses up to 3000 mg daily for up to one year (1114,1119,1120,90642,104104), or up to 6000 mg daily for up to 8 weeks (90644,90645). ...when used topically and appropriately, short-term (11051).

PREGNANCY AND LACTATION:
Insufficient reliable information available; avoid using.

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5-HT4 AGONISTS Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Unlikely •  Level of Evidence = D Theoretically, lysine may reduce the effects of 5-HT4 agonists.  Details Animal research suggests that L-lysine is a partial serotonin receptor 4 (5-HT4) antagonist and inhibits diarrhea induced by the 5-HT4 agonist, 5-hydroxytryptophane (19400).

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General ...Orally and topically, lysine is generally well tolerated.
Most Common Adverse Effects:
Orally: Abdominal pain, diarrhea, and dyspepsia.

Gastrointestinal ...Orally, lysine has been reported to cause diarrhea and abdominal pain, including dyspepsia (1114,1115,1116,1118,1120).

Renal ...There is one case report of oral lysine use associated with tubulointerstitial nephritis progressing to chronic renal failure in a 44-year old female (1121).

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