Cold Sores

Key facts

Cold sores are common and usually start to heal within 10 days. They are caused by the herpes simplex virus and are contagious from the first tingle until they have completely healed — never kiss a baby while you have one.

Most often affects:Anyone who has caught the herpes simplex virus — most people do as childrenDuring illnessAfter time in the sunAround a period

What commonly causes cold sores

• The herpes simplex virus. Once you have it, it stays in your skin for life and sometimes causes a cold sore
• Most people catch it as children, through close skin-to-skin contact such as kissing someone with a cold sore
• A cold sore can be triggered by illness, sunshine or being on your period

What helps at home

• Ask a pharmacist about antiviral cream, and use it as soon as you feel the early tingling — it does not always work once blisters appear
• A pharmacist can also suggest creams to ease pain and irritation, and cold sore patches to protect the skin while it heals
• Take paracetamol or ibuprofen to ease pain and swelling — do not give aspirin to children under 16
• Drink plenty of fluids
• Do not touch the cold sore except to apply cream, and wash your hands before and after
• Dab cream on — do not rub it in
• Avoid acidic or salty food if it makes the cold sore feel worse

When to get help

These three levels are different. Getting the level right is the single most useful thing this page can do for you.

Questions people ask about cold sores

Reducing the chance of it coming back

• Avoid anything you know triggers your cold sores, such as sunbeds
• Use a sunblock lip balm (SPF 15 or above) when you are outside in the sun
• While you have one: do not kiss anyone, and do not have oral sex until it has completely healed — you could give your partner genital herpes
• Never kiss a baby while you have a cold sore. It can cause neonatal herpes, which is very dangerous to newborn babies
• Wash your hands with soap and water whenever you touch your cold sore