Lysine
Supplement
amino acid
immuneskin & hair
Not medical advice. Check with your doctor or pharmacist before you start, stop or change the timing of anything you take.
How to use
What it’s for
An essential amino acid · cold-sore trials are mixed
Pros & cons
Pros
- Above 3 g/d, subjective experience improved in trials
- Diet supplies about 5–6 g a day already
- Noael 6 g/d, loael 7.5 g/d in human dose studies
Cons
- Under 1 g/d looked ineffective for herpes lesions
- Longer controlled trials above 1.2 g/d are needed
- Gallbladder or heart disease — risk is theoretical
Sources
- Lysine for Herpes Simplex Prophylaxis: A Review of the Evidence (Mailoo & Rampes, Integr Med (Encinitas) 2017;16:42) · read 2026-08-27
what it says
“L-lysine supplementation appears to be ineffective for prophylaxis or treatment of herpes simplex lesions with doses of less than 1 g/d without low-arginine diets. Doses in excess of 3 g/d appear to improve patients' subjective experience of the disease.”
- Mailoo & Rampes, Integr Med 2017 — conclusion and cautions · read 2026-08-27
what it says
“Longer duration controlled studies of daily lysine doses exceeding 1.2 g/d are required to definitively test its role in herpes simplex prophylaxis. Patients with cardiovascular or gallbladder disease should be cautioned and warned of the theoretical risks of lysine supplementation.”
- Tolerable Upper Intake Level for Individual Amino Acids in Humans (Elango, Adv Nutr 2023;14) — Table 4 lysine limits and Table 2 dietary intake · read 2026-08-27
what it says
“6 essential amino acids (leucine, tryptophan, methionine, lysine, histidine, and phenylalanine) … [Table 4] Lysine — 6 7.5 2.1 2.7 [UL, NOAEL, LOAEL, EAR, RDA g/d] … [Table 2 intake] Lysine 5.0 3.7–6.0 6.0 12.6”
- Elango, Adv Nutr 2023 — no national agency has set an amino acid upper intake level · read 2026-08-27
what it says
“currently, there are no recommendations set by national health agencies for tolerable upper intake levels (UL) for amino acids because of a lack of well-conducted human dose-response trials”
- HSA Singapore — Health Supplements Guidelines (January 2026), clause 6.6 and Table 6: Examples of Diseases/Conditions/Disorders Not Allowed for Health Supplements · read 2026-08-27
what it says
“HS must not be labelled, advertised or promoted for any specific medicinal purpose, i.e. treatment or prevention, implied or otherwise, of any disease or disorder … Others: Cancers, infectious diseases, inflammatory conditions or diseases”
- HSA — Guidelines on Prohibited and Restricted Ingredients in Health Supplements and Traditional Medicines, GL-CHPB-1-012 (Oct 2025), Annex A/B — searched, no row for this ingredient · read 2026-08-27
what it says
“The objective of this guideline is to highlight the substances of concern when used in HS and TM and is not meant to be an exhaustive list.”
- HSA Singapore — Health Supplements Guidelines (January 2026), clause 4.8 and Tables 4–5 (vitamins and minerals only) · read 2026-08-27
what it says
“HS for use by the general adult population should not contain vitamins and minerals exceeding the stipulated limits stated in Tables 4 and 5.”
- iHerb Singapore — Supplements > Amino Acids > Lysine category page, default order (1 - 48 of 67 results); first 5 distinct brands: California Gold Nutrition, NOW Foods, Solaray, Thorne, Life Extension · read 2026-08-27
what it says
“California Gold Nutrition, L-Lysine, 500 mg, 60 Veggie Capsules … NOW Foods, L-Lysine, 1,000 mg, 100 Tablets … Solaray, L-Lysine Monolaurin, 1:1 Ratio, 60 VegCaps … Thorne, Lysine, 500 mg, 60 Capsules … Life Extension, L-Lysine, 620 mg”
Updated 2026-08-30. Every line above traces to a numbered source. Kozen-X is not a medical device and does not give medical advice. It lists what published sources have written down — nothing more. A pair not listed is unrecorded, not cleared. Before you start, stop or re-time anything, talk to your doctor or pharmacist.