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A cold sore usually starts with a tingling, itching or burning feeling.
Over the next 48 hours one or more painful blisters will appear on your face.
Cold sore blisters are usually small and filled with fluid.
The blisters can appear anywhere on the face.
The blisters burst and crust over into a scab.
Cold sores should start to heal within 10 days, but are contagious and may be irritating or painful while they heal.
Certain things may trigger a cold sore, such as illness, sunshine or being on your period.
| Symptoms | Possible causes |
|---|---|
|
Symptoms
Painful red spot on the face filled with pus |
Possible causes
Spot or boil |
|
Symptoms
Blister on the inside of the lip or mouth |
Possible causes |
|
Symptoms
Red sores or blisters on the face that become crusty, golden-brown patches |
Possible causes |
Cold sores are contagious from the moment you first feel tingling or other signs of a cold sore coming on to when the cold sore has completely healed.
They can easily spread to other people and other parts of your body.
To help stop cold sores spreading:
Kissing a baby if you have a cold sore can lead to neonatal herpes, which is very dangerous to newborn babies.
A pharmacist can recommend:
You can buy electronic devices from pharmacies that treat cold sores with light or lasers.
You may find these helpful, but there's not much evidence to confirm they work.
If you regularly get cold sores, use antiviral creams as soon as you recognise the early tingling feeling. They do not always work after blisters appear.
There are things you can do to help ease cold sores while they heal and to avoid triggering a cold sore.
avoid anything that triggers your cold sores, such as sunbeds
use sunblock lip balm (SPF 15 or above) if you're outside in the sun
take paracetamol or ibuprofen to ease pain and swelling (liquid paracetamol is available for children) – do not give aspirin to children under 16
drink plenty of fluids to avoid dehydration
do not touch your cold sore (apart from applying antiviral cream) – and if you do wash your hands before and after
do not rub cream into the cold sore – dab it on instead
do not eat acidic or salty food if it makes your cold sore feel worse
A GP may prescribe antiviral tablets if your cold sores are very large, painful or keep coming back.
Newborn babies, pregnant women and people with a weakened immune system may be referred to hospital for advice or treatment.
Cold sores are caused by a virus called herpes simplex.
Most people are exposed to the virus when they're children after close skin to skin contact, such as kissing, with someone who has a cold sore.
Once you have the virus, it stays in your skin for the rest of your life. Sometimes it causes a cold sore.
