Cold sores can be easy to spot, thanks to their tell-tale symptoms. While there's no cure for the recurring infection, treatments can help to speed up healing and relieve any pain.

What are the causes?

Cold sores are small, blister-like lesions that usually occur on the edge of the lips. They are caused by the herpes simplex type 1 virus (HSV-1). In most cases, it is caught in childhood. The virus travels up a nerve where it lies dormant until it is triggered at a later date. The initial infection doesn't usually cause any symptoms, so the child will not know that they've been infected.

About 70 per cent of the adult population are infected with the virus, but only a quarter suffer regularly from cold sores. Many will have two or three outbreaks every year. Men and women are equally likely to be affected and it can occur at any age.

When activated, the virus multiplies and travels down the nerve to cause cold sores on the edge of the lips, chin or nose. Specific triggers can activate the virus in different people, such as being ill with a cold or the flu; being upset or under stress, or being in strong sunshine or cold weather for any length of time. Some women may also find it is linked to their menstrual cycles.

What are the symptoms?

Cold sores usually start with a tingling or burning sensation, which can last for up to one or two days. The skin then turns red and develops into one or more blisters that often fill with fluid €“ these may weep and are often tender and painful. It can take several days for the blisters to scab over and seven to 10 days to heal.

The fluid in the blisters contains the HSV-1 virus, so until the blisters have healed, the cold sore is infectious and can easily be spread to other people. Therefore, sufferers should not kiss or have skin contact with other people, particularly young babies and those with a weak immune system. Good personal hygiene will also help to stop the spread of the infection.