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Lysine for Weight Loss?
Lysine, an essential amino acid, is often promoted as a weight-loss supplement. However, current research doesn’t back this claim—in fact, it suggests the opposite. A small human study found that taking lysine daily didn’t impact weight loss compared to a placebo. Surprisingly, participants taking lysine lost less weight than those in the placebo group.
Animal studies support this trend. Research on rats showed that removing lysine from their diet slowed weight gain, implying lysine supplementation might contribute to weight gain rather than weight loss. Based on these findings, lysine isn’t a viable tool for shedding pounds and might even hinder your efforts.
But lysine does offer other noteworthy health benefits. Let’s explore its proven uses and limitations.
Benefits of Lysine

Cold Sores
One of lysine’s most well-supported benefits is its ability to combat cold sores caused by the herpes simplex virus (HSV). Lysine interferes with HSV replication by competing with another amino acid, arginine, which the virus relies on to reproduce.
Studies reveal that taking 1,000 to 3,000 mg of lysine daily can prevent outbreaks and reduce the recurrence of herpes infections compared to a placebo. Long-term supplementation (6–12 months) has also been shown to lessen the severity of outbreaks and speed up healing.
Topical lysine, especially when combined with zinc, can further decrease symptoms and shorten the duration of cold sores. However, while there’s limited evidence lysine might help with canker sores, these are typically caused by stress or dietary factors—not a virus—so the connection is much weaker.
Schizophrenia
Emerging research suggests lysine may help individuals with schizophrenia, particularly when used alongside antipsychotic medications. A study found that taking 6 grams of lysine daily for eight weeks led to significant improvements in negative and psychopathological symptoms compared to a placebo. While promising, more research is needed to confirm these benefits.
Nutritional Benefits?
Lysine’s benefits extend to general health, especially in populations with protein deficiencies. As an essential amino acid, your body cannot produce lysine, so it must come from dietary sources like meat, fish, dairy, eggs, soy, and legumes. These foods support muscle growth, immunity, and overall health.
For individuals in developed countries, lysine deficiencies are rare due to balanced diets. This makes lysine supplementation largely unnecessary—except for targeted uses like treating cold sores. Despite claims, lysine hasn’t shown reliable benefits for fighting colds, flu, or enhancing muscle growth.
Summary
Lysine isn’t a weight-loss aid, and its benefits are mostly limited to specific health concerns like cold sores and schizophrenia. If you’re eating a varied diet, you’re likely getting enough lysine naturally. Supplements may only be worthwhile for addressing cold sores or specific medical conditions under professional guidance.
Top supplement choices
- L-Lysine (caps) – 1 to 3 caps / day
- L-Lysine (powder) – 1 to 3 tsp / day
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Citations
Griffith RS, Walsh DE, Myrmel KH, Thompson RW, Behforooz A. Success of L-lysine therapy in frequently recurrent herpes simplex infection. Treatment and prophylaxis. Dermatologica. 1987;175(4):183-90. PMID: 3115841.
McCune MA, Perry HO, Muller SA, O’Fallon WM. Treatment of recurrent herpes simplex infections with L-lysine monohydrochloride. Cutis. 1984 Oct;34(4):366-73. PMID: 6435961.
Moro J, Roisné-Hamelin G, Chaumontet C, Even PC, Blais A, Cansell C, Piedcoq J, Gaudichon C, Tomé D, Azzout-Marniche D. Lysine or Threonine Deficiency Decreases Body Weight Gain in Growing Rats despite an Increase in Food Intake without Increasing Energy Expenditure in Response to FGF21. Nutrients. 2022 Dec 30;15(1):197. doi: 10.3390/nu15010197. PMID: 36615854; PMCID: PMC9824894.
Singh BB, Udani J, Vinjamury SP, Der-Martirosian C, Gandhi S, Khorsan R, Nanjegowda D, Singh V. Safety and effectiveness of an L-lysine, zinc, and herbal-based product on the treatment of facial and circumoral herpes. Altern Med Rev. 2005 Jun;10(2):123-7. PMID: 15989381.
Sun F, Chao L, Zhang J, Pan X. Exercise combined with lysine-inositol vitamin B12 promotes height growth in children with idiopathic short stature. Growth Horm IGF Res. 2023 Apr-Jun;69-70:101535. doi: 10.1016/j.ghir.2023.101535. Epub 2023 May 16. PMID: 37245296.
Wright EF. Clinical effectiveness of lysine in treating recurrent aphthous ulcers and herpes labialis. Gen Dent. 1994 Jan-Feb;42(1):40-2; quiz 51-2. PMID: 8005397.
Zeinoddini A, Ahadi M, Farokhnia M, Rezaei F, Tabrizi M, Akhondzadeh S. L-lysine as an adjunct to risperidone in patients with chronic schizophrenia: a double-blind, placebo-controlled, randomized trial. J Psychiatr Res. 2014 Dec;59:125-31. doi: 10.1016/j.jpsychires.2014.08.016. Epub 2014 Sep 6. PMID: 25227564.
See also
- The Truth About Vitamin PatchesVitamin patches don’t work well since most nutrients can’t pass through the skin. The main exceptions are Vitamin D and caffeine.
- CoQ10: Benefits and MythsCoQ10 supports heart health, some muscle conditions, and PCOS, but doesn’t help with fertility, athletic performance, or weight loss.
- Propolis Throat Sprays for Sore ThroatsPropolis throat sprays can provide some relief for sore throats and irritated mucous membranes, but they don’t work as well as honey.
- Benefits of Niacinamide SerumsNiacinamide, even at 10%, is safe, effective, and gentle, improving skin health with little risk of irritation.
- Real Benefits of Lemon BalmLemon balm may help with mental health issues like depression and stress and could also aid in treating cold sores.
Correction:
Legumes and soy are NOT a good source of Lysine, because their levels of Arginine, which competes directly with Lysine, are much higher. (Look up this ratio in foods to see this).
Dairy/yogurt/cheeses, certain fruits (especially apricots, figs, papaya and mango), fish, and certain veggies remain the best sources of Lysine.
Legumes, nuts and grains, are amoung the WORST sources of Lysine (though of CB purse they are healthy in other ways).