{"ok":true,"entry":{"slug":"lysine","kind":"supplement","name":"lysine","aliases":["L-lysine"],"brands_sg":["California Gold Nutrition","NOW Foods","Solaray","Thorne","Life Extension"],"class":"amino acid","tags":["immune","skin-hair"],"use_for":"an essential amino acid · cold-sore trials are mixed","use_after":null,"use_duration":null,"take_with":null,"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"],"dose_note":"the 2017 review reports that l-lysine appeared ineffective at doses under 1 g a day without a low-arginine diet, that doses above 3 g a day improved how patients rated their own experience, and that longer controlled studies above 1.2 g a day are still needed; the 2023 amino-acid review lists a noael of 6 g a day and a loael of 7.5 g a day against an ear of 2.1 g and an rda of 2.7 g, and states that no national health agency has set an upper intake level for any amino acid; hsa's tables 4–5 cover vitamins and minerals only, so no sg daily maximum applies","dosage":{"ul":null,"unit":"g","fda_dv":null,"rda_ai":2.7,"ul_status":"none_established","population":"general adult","hsa_max_daily":null},"ul_status":"none_established","sg_class":null,"cautions":["cardiovascular or gallbladder disease — the 2017 review flags theoretical risks","singapore: supplements cannot be labelled or promoted for infectious diseases (hsa table 6)","the noael and loael come from healthy adults, mostly young","singapore: not listed in hsa annex a or b, which is not a safety clearance"],"clashes":[],"sources":[{"id":"mailoo2017","url":"https://europepmc.org/article/PMC/PMC6419779","label":"Lysine for Herpes Simplex Prophylaxis: A Review of the Evidence (Mailoo & Rampes, Integr Med (Encinitas) 2017;16:42)","quote":"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.","accessed":"2026-08-27"},{"id":"mailoo2017_caution","url":"https://europepmc.org/article/PMC/PMC6419779","label":"Mailoo & Rampes, Integr Med 2017 — conclusion and cautions","quote":"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.","accessed":"2026-08-27"},{"id":"elango2023_lysine","url":"https://europepmc.org/article/PMC/PMC10334138","label":"Tolerable Upper Intake Level for Individual Amino Acids in Humans (Elango, Adv Nutr 2023;14) — Table 4 lysine limits and Table 2 dietary intake","quote":"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","accessed":"2026-08-27"},{"id":"elango2023_gap","url":"https://europepmc.org/article/PMC/PMC10334138","label":"Elango, Adv Nutr 2023 — no national agency has set an amino acid upper intake level","quote":"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","accessed":"2026-08-27"},{"id":"hsa_hs_claims","url":"https://file.go.gov.sg/hsa-hs-guidelines.pdf","label":"HSA Singapore — Health Supplements Guidelines (January 2026), clause 6.6 and Table 6: Examples of Diseases/Conditions/Disorders Not Allowed for Health Supplements","quote":"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","accessed":"2026-08-27"},{"id":"hsa_pr_notlisted","url":"https://file.go.gov.sg/hsa-chp-prohibited-restricted-ing-guidelines.pdf","label":"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","quote":"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.","accessed":"2026-08-27"},{"id":"hsa_hs_limits","url":"https://file.go.gov.sg/hsa-hs-guidelines.pdf","label":"HSA Singapore — Health Supplements Guidelines (January 2026), clause 4.8 and Tables 4–5 (vitamins and minerals only)","quote":"HS for use by the general adult population should not contain vitamins and minerals exceeding the stipulated limits stated in Tables 4 and 5.","accessed":"2026-08-27"},{"id":"iherb_sg","url":"https://sg.iherb.com/c/l-lysine","label":"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","quote":"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","accessed":"2026-08-27"}],"brand_certs":[{"brand":"Thorne","example":null,"programme":"NSF Certified for Sport","matching_products":0,"brand_total_certified":66}],"updated_at":"2026-08-30T17:59:36.026222+08:00"},"disclaimer":"kozen-x is not a medical device and does not give medical advice. it lists what published sources have written down. absence of a record is not the same as safe."}