Lysine is an essential amino acid that is used to build proteins in the body. The body is unable to synthesize this amino acid, so it must be obtained from food sources or from Lysine supplements.
Lysine is involved in energy metabolism, growth, calcium utilization, bone health, nitric oxide levels and collagen synthesis. We derive this nutrient from foods such as fish, meat and protein-rich nuts.
Some people, such as vegans, may take these supplements to ensure they obtain enough of this nutrient in their diets. Lysine supplements are also used to support the immune system, for herpes simplex labialis breakouts, Bell’s palsy, osteoporosis, metabolic alkalosis and enhancing athletic performance.
Some research supports the use of Lysine for herpes, although other studies have provided conflicting results. More research is needed to confirm potential benefits for this and other purposes.



- Promotes health skin & bones
- Boosts immunity & antibody production
- Supports tissue repair & hormone balance
What Do Lysine Supplements Do?
The most common medicinal use of Lysine is for herpes labialis, or cold sores. Lysine is purported to reduce the healing time of herpes outbreaks, and to lower the risk of recurrence.
Research is mixed on whether Lysine is an effective treatment for this purpose. The Natural Medicines Database rates it as possibly effective for this use because some research has shown improvements while other research has shown no benefit.
A double-blind and placebo-controlled trial found that 1,000 mg of Lysine supplements taken three times daily reduced herpes simplex infection rates, severity of symptoms and duration of recurrent infections. This study was conducted over a six-month period. [1]
An additional small pilot study used a topical ointment of Lysine with other nutrients and botanicals on cold sores. The cold sore was diminished in three days in 40 percent of study participants and in six days in 87 percent.
This significantly shortened the normal untreated cold sore duration, which can last up to 21 days. However, because the treatment used a combination of lysine with other ingredients, it is not possible to determine whether lysine would have this effect on its own. [2]
According to the University of Maryland Medical Center, some researchers believe Lysine may benefit osteoporosis by supporting bone health, although human studies are needed on this subject. [3]
Conversely, the Natural Medicines Database notes that Lysine may interact with osteoporosis when taken with calcium supplements by affecting the balance of calcium absorption and loss.
Lysine is purported to enhance sports performance by supporting muscle tissue recovery. More research is needed on this potential benefit.
This supplement has also been researched for its effects on the immune system, stress, canker sores and diabetes, although more research is required to support any purported benefits for these uses.
Lysine Supplement Dosage
To promote healthy function of the body, the recommended dietary allowance of lysine for adults is 38 mg/kg of bodyweight per day. For pregnant and nursing women, the RDAs are 51 mg /kg and 52 mg/kg a day.
For herpes infections, Drugs.com notes that Lysine supplements could be taken in doses from 500 mg to 3 g each day as a preventive measure. Higher doses are used for herpes breakouts. [4]
UMMC recommends having a doctor determine your dosage as it could vary depending on the intended use and other factors.
Children need lysine in their diets to support a healthy body. For children, the recommended dietary allowance from the USDA is as follows:
- 89 mg a day for those 7 to 12-months’ old
- 58 mg a day for those 1 to 3-years’ old
- 40 to 46 mg a day for those 4 to 18-years’ old
Lysine supplement for kids are available at lower doses that the amounts typically given to adults. Doses for pediatric applications should be determined by a doctor.
According to the Institute of Medicine of the U.S. National Academy of Sciences, more research is needed to determine a tolerable upper intake level (UL) for lysine in healthy adults and children.
Are Lysine Supplements Safe?
The Natural Medicines Database rates oral Lysine supplementation as possibly safe for a period of up to one year. NMD notes that side effects are possible with higher doses, including gastrointestinal discomfort.
Lysine is generally well-tolerated as a dietary supplement, but could cause abdominal cramping, stomach upset, gallstones and other adverse reactions, especially at high doses.
This supplement may interact with certain drugs, supplements and health conditions. Consult with a doctor before taking lysine pills of you are using 5-HT4 agonist drugs or calcium supplements.
Lysine is contraindicated for individuals with kidney disease, osteoporosis, and lysinuric protein intolerance. It may interfere with cancer imaging lab tests. Discontinue use before undergoing diagnostic cancer imaging.
Drugs.com notes that Lysine seems to be safe for pre-pubertal children when taken in doses of 1 to 3 g a day. The UMMC recommends the dosage be customized to each child’s weight.
There is insufficient evidence to determine how this supplement could affect pregnant and lactating women. Out of an abundance of caution, its use should be avoided in these populations.
Lysine supplementation could be beneficial for those not getting enough of this nutrient in the diet. This is not common, but could be found in certain populations such as vegans.
Some individuals use lysine to support their immune system, promote muscle growth and boost athletic performance. It may also support healthy bones and calcium utilization, but more research is needed to understand its effects.
Those considering Lysine supplementation should talk to a doctor in to determine whether this supplement is appropriate for their needs.
- Griffith RS et al. Success of L-lysine therapy in frequently recurrent herpes simplex infection. Treatment and prophylaxis. Dermatologica. (1987).
- Singh BB et al. Safety and effectiveness of an L-lysine, zinc, and herbal-based product on the treatment of facial and circumoral herpes. Altern Med Rev. (2005).
- Lysine. University of Maryland Medical Center.
- Lysine. Drugs.com.
Article last updated on: March 12th, 2018 by Nootriment