Cold sores: Just the facts

Cold sores are blisters that develop around the lips and mouth caused by the herpes simplex virus. They are contagious, but usually clear up without treatment within 7 to 10 days. 

Cold sores only develop if you have been infected with the herpes simplex virus, which might have been from close contact with someone with a cold sore. You won’t usually have any symptoms immediately after coming into contact with herpes simplex, and a cold sore outbreak might not occur until some time later. 

Once you have the virus, it stays in your body for the rest of your life. Some people might have a few cold sore outbreaks a year, others may only ever have one cold sore outbreak. 

Spots around your face are really common, so just because you have a spot around your mouth does not mean that it’s a cold sore. It could be a spot, boil or even a mouth ulcer if the blister is inside the mouth. 

How do I know if it’s a cold sore?

Cold sores often start with a tingling, itching or burning feeling, small fluid-filled blisters will then begin to appear after a couple of days. The blisters will then burst and crust over into a scab. They might be irritating and painful whilst they heal. 

How long are cold sores contagious for?

Cold sores are contagious from the moment you feel them coming on until they are completely healed. If you think you might have, or are developing, a cold sore, avoid close contact with others until the sore is completely healed, such as: 

• kissing and oral sex 
• sharing creams, moisturisers and make-up with others 
• sharing items that come into contact with the affected area, such as cutlery, vapes or cigarettes 

Try not to touch a cold sore unless you are applying cream to the area and, wash your hands afterwards to make sure you don’t transmit the virus. 

You should be especially careful around newborn babies, pregnant people and those with weaker immune systems such as individuals with HIV or those going through chemotherapy, as they are at higher risk of complications. 

See a pharmacist if the cold sore hasn’t healed after 7 to 10 days, they will be able to recommend creams or patches to ease the pain or speed up the healing process. Cold sores aren’t usually serious, so you won’t need to contact a GP unless recommended by a pharmacist or if you are worried about your cold sore, for example if you have a weakened immune system or if the cold sore is particularly large or painful. 

Find your local pharmacist here.