Cold sores

What are cold sores?

A cold sore is a blister on or around the lips caused by the herpes simplex virus (HSV). They start off small, grow larger over a period of a couple of days, and usually burst and scab over before healing. They’re not strictly a health risk, but they can be painful and unsightly. It’s easy to give them to someone else when you have them by kissing or sharing unwashed glasses or utensils (like cutlery). The virus can also be passed on from mothers to children.

Cold sores are caused by a virus that stays with you for life once you have it. Treatment doesn’t eradicate them completely, but if you use it early enough during an outbreak, it can stop them from developing and shorten the time it takes them to heal.

Outbreaks tend to happen when HSV, which can lie dormant for long periods, is reactivated. Reactivation can be brought on by various things like stress, being run down or an illness. It’s quite common for cold sores to spring up when your immune system isn’t at its strongest. So this might be if you’ve picked up another infection. It’s also possible to get them if you have the virus and get a lip injury (like a cut).

Herpes is often thought of as a sexually transmitted disease, but there are two types of herpes virus. Type 1 (HSV-1), which is the more common of the two, is more closely associated with cold sores. Type 2 (HSV-2), is more closely associated with genital herpes and tends to affect the groin and anal area. HSV-2 is more often passed on through sex. But either virus can be responsible for either symptom (cold sores or genital herpes).

Who gets cold sores?

Anyone can get a cold sore. There’s nothing that makes anyone more susceptible to infection than someone else with the virus. But if you have a weakened immune system, you’re more likely to get worse outbreaks more often.

Once you have the HSV virus, it stays with you for life and unfortunately, there isn’t a cure. But for most people, the outbreaks they get will become less severe and less frequent with age. Symptoms of cold sores will usually subside on their own after a couple of weeks, but treatment can help to speed this up.

Some people may get cold sore flare ups two or three times a year, while others could get one in their entire lives, and never have the issue again. So it’s quite dependent on the individual, and their health can be a factor in how many they get as well.

It’s common to get outbreaks if you’re stressed , or if your immune system is compromised after a bout of cold or flu. So keeping a healthy lifestyle is important to minimise flare ups.

How common are cold sores?

According to the WHO, an estimated two thirds of the world's population under 50 are infected with herpes simplex virus type 1 (HSV1) , that causes cold sores. But not everyone who has the herpes virus gets symptoms, meaning they would never know they had it.

A vast majority of HSV1 infections globally are oral herpes (infections in or around the mouth, sometimes called oral-labial or oral-facial herpes), but a proportion of HSV1 infections are genital herpes.