How to Take Lysine for Fever Blisters

Fever blisters, also known as cold sores, are caused by the herpes simplex 1 virus. The virus lies dormant in your body and is usually kept in check by your immune system until something, such as an illness or stress, weakens your system and triggers an outbreak. Lysine, an amino acid, may help prevent or reduce the duration of these outbreaks, according to the University of Maryland Medical Center. Lysine is available in tablet form in the supplement section of most major drugstores. Always consult your physician before starting a supplement program.

Woman with fever blisters on her lips Credit: apichsn/iStock/Getty Images

Step 1

Swallow one 1,000-mg capsule of lysine. Consume the supplement three times per day, with a full glass of water or juice, to prevent outbreaks. Take one dose in the morning, one at midday and one in the evening.

Step 2

Take up to 9,000 mg per day to treat an outbreak. Use the lysine at the first sign of a fever blister, usually when you feel the distinctive tingle in your lip. Break the doses up into three daily doses and take it with a full glass of water. Continue using this dose until the fever blister heals.

Step 3

Make lifestyle changes. Eat a healthy diet, get adequate rest and wear sunblock to help prevent further outbreaks, according to


If you continue to get frequent outbreaks, or if this outbreak does not resolve within 14 days, consult your physician for more aggressive treatment.


High doses of lysine may cause gallbladder disease, according to the University of Maryland Medical Center. Do not take more than the recommended dose, and do not take the 9,000 mg dose after the fever blister has healed. If you are pregnant, nursing or have kidney disease, consult your physician before taking lysine. Do not take lysine with arginine supplements. Arginine may lower your lysine levels. Avoid kissing or sharing utensils with others during an outbreak. Avoid touching your eyes or genitals during an outbreak. You may spread the virus to these areas, according to

Is This an Emergency?

If you are experiencing serious medical symptoms, seek emergency treatment immediately.
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