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:
Important
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.
Information:
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.
Do
Don’t
Non-urgent advice:
See a GP if:
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.