Lysine
Lysine is an essential amino acid studied mainly for cold sores and related outcomes. Evidence is mixed.
Overview
What is lysine?
Lysine is an essential amino acid commonly used to treat cold sores.
Dosage
A typical dose of lysine is 2 grams per day, split into 3-4 doses.
Effect graph
Effect heatmap
SupplementDEX Database
10 conditions for , and rated at least stars. All purchase bands. No minimum star filter.
Database Snapshot
Most lysine research is concentrated in a handful of conditions.
- Cold sores accounts for 10 of 20 studies (50%).
- Schizophrenia accounts for 2 of 20 studies (10%).
- Diabetic foot ulcers accounts for 1 of 20 studies (5%).
- Sparse coverage remains for Schizophrenia, Diabetic foot ulcers, High blood pressure.
Safety
Lysine is possibly safe when used at doses of up to 3,000 mg daily for one year, or 6,000 mg daily for up to 8 weeks.
Frequently Asked Questions
References
Sources20 references
SupplementDEX uses only high-quality sources to determine supplement effectiveness.
SupplementDEX Database · Cold sores
10 references1.SupplementDEX Database: Cold sores — Interventions for prevention of herpes simplex labialis (cold sores on the lips)2015
A Cochrane review of 32 RCTs (2,640 participants) found oral aciclovir 400 mg twice daily modestly reduced herpes labialis recurrence (RR 0.26), while evidence for other preventive agents including lysine was limited or inconclusive.
2.SupplementDEX Database: Cold sores — Safety and effectiveness of an L-lysine, zinc, and herbal-based product on the treatment of facial and circumoral herpes2005
An open-label study of a topical L-lysine, zinc, and herbal cream in facial/circumoral herpes found 87% of lesions fully resolved by day 6 vs typical 21-day course without treatment.
3.SupplementDEX Database: Cold sores — Clinical effectiveness of lysine in treating recurrent aphthous ulcers and herpes labialis1994
A clinical report on oral lysine for recurrent aphthous ulcers and herpes labialis suggested symptomatic benefit, though the uncontrolled design limits firm conclusions.
4.SupplementDEX Database: Cold sores — Success of L-lysine therapy in frequently recurrent herpes simplex infection. Treatment and prophylaxis1987
A 6-month randomized trial in patients with frequently recurrent herpes simplex infection found that oral L-lysine (1 g three times daily) significantly reduced the number of recurrences, symptom severity, and healing time compared with placebo, supporting its use for both treatment and prophylaxis.
5.SupplementDEX Database: Cold sores — Lysine as a prophylactic agent in the treatment of recurrent herpes simplex labialis1984
A 12-month double-blind crossover RCT of 26 patients with recurrent herpes labialis found 1,000 mg/day lysine significantly reduced lesion frequency when serum lysine exceeded 165 nmol/mL.
6.SupplementDEX Database: Cold sores — Treatment of recurrent herpes simplex infections with L-lysine monohydrochloride1984
A double-blind crossover RCT of 41 patients found 1,248 mg/day L-lysine reduced herpes simplex recurrence rate and severity, while 624 mg/day was ineffective.
7.SupplementDEX Database: Cold sores — Failure of lysine in frequently recurrent herpes simplex infection. Treatment and prophylaxis1984
A double-blind RCT of 21 patients with frequent herpes recurrences found 1,200 mg/day lysine did not significantly improve recurrence rate or severity vs placebo.
8.SupplementDEX Database: Cold sores — Subjective response to lysine in the therapy of herpes simplex1983
A survey of 1,543 patients taking ~936 mg/day lysine for 6 months reported 84% felt it prevented or reduced herpes recurrence frequency and 83% said lesions healed within 5 days.
9.SupplementDEX Database: Cold sores — Lysine prophylaxis in recurrent herpes simplex labialis: a double-blind, controlled crossover study1980
A double-blind crossover RCT of 65 patients found 1,000 mg/day lysine prophylaxis produced significantly more recurrence-free periods vs placebo (p=0.05), though overall recurrence rates did not differ.
10.SupplementDEX Database: Cold sores — A multicentered study of lysine therapy in Herpes simplex infection1978
A multicenter study of 45 patients with recurrent herpes simplex given 312–1,200 mg/day lysine found accelerated recovery and reduced recurrence in a substantial proportion of participants.
11.SupplementDEX Database: Diabetic foot ulcers — Efficacy of 15% lysine cream in treating diabetic foot ulcers: a randomized interventional study2023
A 6-week RCT of 40 diabetic foot ulcer patients found topical 15% lysine cream plus standard care significantly improved wound healing scores vs standard care alone (P<0.05).
SupplementDEX Database · High blood pressure
1 reference12.SupplementDEX Database: High blood pressure — Effect of lysine supplementation on hypertensive men and women in selected peri-urban community in Ghana2017
A 112-day RCT of 50 hypertensive adults in Ghana found lysine supplementation (1,000 mg/day) reduced systolic BP from 146 to 129 mmHg vs minimal change on placebo.
SupplementDEX Database · High triglycerides
1 reference13.SupplementDEX Database: High triglycerides — Effect of lysine, vitamin B(6), and carnitine supplementation on the lipid profile of male patients with hypertriglyceridemia: a 12-week, open-label, randomized, placebo-controlled trial2012
In hypertriglyceridemic adults, lysine/vitamin B6/carnitine supplementation for 12 weeks improved triglycerides and selected lipoproteins versus baseline.
14.SupplementDEX Database: Idiopathic short stature — Exercise combined with lysine-inositol vitamin B12 promotes height growth in children with idiopathic short stature2023
A 12-month RCT of 60 children with idiopathic short stature found exercise plus lysine-inositol-vitamin B12 significantly increased growth velocity and GH/IGF-1 levels vs supplement alone.
SupplementDEX Database · Muscle strength
1 reference15.SupplementDEX Database: Muscle strength — The effect of a controlled 8-week metabolic ward based lysine supplementation on muscle function, insulin sensitivity and leucine kinetics in young men2012
An 8-week RCT of 40 young men found high-dose lysine (80 mg/kg/day) produced only a small ~7.5% improvement in muscle strength vs lower doses, with no effect on insulin sensitivity.
SupplementDEX Database · Pressure ulcers
1 reference16.SupplementDEX Database: Pressure ulcers — Effect of lysine hyaluronate on the healing of decubitus ulcers in rehabilitation patients2011
A 15-day double-blind RCT in rehabilitation patients with pressure ulcers found lysine hyaluronate produced greater lesion size reduction than sodium hyaluronate across all ulcer stages.
SupplementDEX Database · Schizophrenia
2 references17.SupplementDEX Database: Schizophrenia — L-lysine as an adjunct to risperidone in patients with chronic schizophrenia: a double-blind, placebo-controlled, randomized trial2014
An 8-week RCT of 72 chronic schizophrenia patients found adjunctive 6 g/day L-lysine plus risperidone significantly improved PANSS negative and general psychopathology subscales vs placebo.
18.SupplementDEX Database: Schizophrenia — L-lysine as adjunctive treatment in patients with schizophrenia: a single-blinded, randomized, cross-over pilot study2011
An 8-week single-blind crossover pilot of 10 schizophrenia patients found 6 g/day L-lysine significantly reduced positive PANSS scores and was well tolerated.
SupplementDEX Database · Stress
1 reference19.SupplementDEX Database: Stress — Lysine fortification reduces anxiety and lessens stress in family members in economically weak communities in Northwest Syria2004
A double-blind RCT in economically disadvantaged Syrian households found lysine-fortified wheat flour reduced chronic anxiety scores and cortisol stress responses, especially in males.
SupplementDEX Database · Type 2 diabetes
1 reference20.SupplementDEX Database: Type 2 diabetes — Effect of oral supplementation of free amino acids in type 2 diabetic patients-- a pilot clinical trial2002
A 2-month double-blind pilot of 77 type 2 diabetes patients found oral amino acid supplementation (including lysine) modestly reduced postprandial glucose without changing insulin levels.