Cold sores are common and usually clear up on their own within 10 days
They're caused by the herpes simplex virus
A cold sore usually starts with tingling, itching, or a burning feeling
They're contagious from the first sign of tingling until fully healed
Certain triggers, like illness, sunshine, or your period, can bring one on
About Cold Sores
Cold sores are common and usually clear up on their own within 10 days, though there's plenty you can do to ease the discomfort while they heal. A cold sore usually starts with a tingling, itching or burning sensation, followed within 48 hours by one or more painful, fluid-filled blisters on the face — these can appear anywhere on the face, and eventually burst and crust over into a scab. Certain things can trigger a cold sore, including illness, sunshine, or being on your period.
Could It Be Something Else?
A painful red spot filled with pus is more likely to be an ordinary spot or a boil, a blister inside the lip or mouth is more likely a mouth ulcer, and red sores that become crusty, golden-brown patches could be impetigo rather than a cold sore.
How Contagious They Are
Cold sores are contagious from the very first tingling sensation right through until the sore has completely healed, and can easily spread to others or to other parts of your own body. To help stop them spreading, wash your hands with soap and water whenever you touch the cold sore, avoid kissing anyone while you have one, and avoid oral sex until it's fully healed, since this could pass on genital herpes to a partner.
Kissing a baby while you have a cold sore can lead to neonatal herpes, which is very dangerous for newborns, so extra caution is essential around young babies.
Why They Keep Coming Back
Cold sores are caused by the herpes simplex virus. Most people are exposed to it in childhood, usually through skin-to-skin contact such as kissing someone with a cold sore. Once you've had the virus, it stays in your skin for life, and can occasionally reactivate to cause a cold sore.
Page last reviewed: 6 March 2024 · Next review due: 6 March 2027
Cold Sores · Self-Care
Treating a Cold Sore Yourself
? 5 min readReviewed: March 2024
Getting Advice from a Pharmacist
A pharmacist can recommend creams to ease pain and irritation, antiviral creams to help speed up healing, and cold sore patches to protect the skin while it heals. If you get cold sores regularly, using an antiviral cream as soon as you notice the early tingling sensation gives the best results, since they don't work as well once blisters have already appeared. Electronic light or laser devices are also sold in pharmacies for treating cold sores, though there isn't much evidence confirming they work.
What Can Help
Avoiding known triggers, such as sunbeds, using a sunblock lip balm (SPF 15 or above) if you're out in the sun, taking paracetamol or ibuprofen for pain and swelling (liquid paracetamol is available for children, and aspirin shouldn't be given to under-16s), and drinking plenty of fluids to avoid dehydration can all help.
What to Avoid
Try not to touch the cold sore, other than to apply antiviral cream — and wash your hands before and after if you do. Dab cream onto the sore rather than rubbing it in, and avoid acidic or salty foods if they make the discomfort worse.
Page last reviewed: 6 March 2024 · Next review due: 6 March 2027
Cold Sores · Getting Help
When to See a GP
? 3 min readReviewed: March 2024
Seeing a GP
See a GP if a cold sore hasn't started healing within 10 days; you're worried it might be something else; it's very large or painful; you or your child also have swollen, painful gums and mouth sores (gingivostomatitis); or you have a weakened immune system, for example due to chemotherapy or diabetes.
Treatment from a GP
A GP may prescribe antiviral tablets if cold sores are particularly large, painful, or keep recurring. Newborn babies, pregnant women, and people with a weakened immune system may be referred to hospital for further advice or treatment given the higher risks involved for these groups.
Page last reviewed: 6 March 2024 · Next review due: 6 March 2027
