Can l-lysine help prevent cold sores?

Cold sores are almost always caused by the herpes simplex 1 virus, which is transmitted via skin-to-skin contact. It doesn’t have to be sexual contact either – a goodbye kiss on the cheek from Aunt Ethel will do it. Outbreaks can be triggered by sunlight, fatigue, injury to the face or even hormonal changes during your period which can ‘wake up’ the virus.

The first sign is usually a tingling, itching or burning sensation around the mouth. Small fluid-filled blisters will then appear, often on the edge of your lower lip. If the blisters burst, this exposes the raw skin underneath which then scabs over. Many people never show symptoms, while others can experience a single outbreak. But an unlucky few will experience recurrent cold sores.

L-lysine is an essential amino acid, a building-block of protein that can’t be produced by the body but is essential for good health. Our immune system needs this amino acid to produce antibodies. It also helps the body absorb calcium, produce collagen and build muscle.

The herpes virus needs arginine – another amino acid – to reproduce. Research shows that l-lysine can block arginine absorption, so could it stop cold sores in their tracks?

A study carried out in 1987 discovered that people who took 1,000mg of l-lysine three times a day for six months developed fewer cold sores – and the ones they did get were less severe and didn’t last as long. Cold sores can last for up to 21 days, but another study published in Alternative Medicine Review found a cream containing l-lysine cleared them up in 40% of those tested within three days, and 87% within six days.

Try taking an l-lysine supplement as soon as you feel the tell-tale tingle (don’t take them as a precautionary measure as they could cause side-effects if taken for a long time). Rubbing a cream or ointment containing l-lysine directly onto your lip may help too.

You can also find l-lysine naturally in red meat, fish, eggs, cheese, legumes such as chickpeas, kidney beans and lentils, and pulses.