Cold sores

What a cold sore is

The NHS is direct about it: cold sores are caused by a virus called herpes simplex. Most people are exposed in childhood, through ordinary close contact with someone who has one — a relative, a friend, nothing to do with sex. And once you have it, it stays in your skin for the rest of your life.

This is extremely common. The World Health Organization estimates 3.8 billion people under 50 — about two in three — carry HSV-1, the type behind most cold sores. If you have had one, you are in the large majority.

How long they last

The NHS says cold sores usually clear up on their own within 10 days. They tend to follow a recognisable arc: a tingling or burning warning, then a blister, then crusting, then healing. Most people learn their own pattern quickly.

What sets them off

The NHS names a few: illness, sunshine, or being on your period. In practice people report all sorts of triggers, and those personal associations are worth noticing even where the evidence is thin — keeping a simple note of when yours appear is more useful than any general list. The same caveat applies here as in outbreaks and triggers: commonly described is not the same as firmly established.

What helps

A pharmacist can help without an appointment. The NHS lists creams to ease pain and irritation, antiviral creams to speed up healing time, and cold sore patches. For severe or repeatedly recurring cold sores, a GP may prescribe antiviral tablets.

What none of it does is remove the virus. There is no cure, and the honest framing is management — the same framing that applies everywhere else on the body.

Cold sores and oral sex

This is the part that most often goes unsaid, and it matters. The NHS advises plainly: do not have oral sex until your cold sore completely heals, as you could give your partner genital herpes.

That is the mechanism behind a great deal of genital HSV-1, and it is why the old tidy split — HSV-1 above the waist, HSV-2 below — no longer holds. It also means a genital herpes diagnosis says nothing reliable about how anyone acquired it. We go into that in HSV-1 vs HSV-2.

Never kiss a baby if you have a cold sore

The single most important line on the NHS page: kissing a baby if you have a cold sore can lead to neonatal herpes, which is very dangerous to newborn babies.

This is not a small precaution and it is not scaremongering. If you have an active cold sore, do not kiss a newborn, and say so to anyone who is about to. If you are pregnant or around a newborn, herpes and pregnancy covers more.

The double standard, stated plainly

A cold sore is treated as a minor nuisance. You can buy a patch for it next to the plasters. Nobody rehearses how to tell a partner about one.

It is the same virus family, behaving the same way, managed the same way. The difference in how the two are received is not a medical fact — it is a social one, and a fairly recent one at that. That is the whole argument of herpes myths, and, more or less, the reason this brand exists at all.