Cold Sores or Herpes Simplex

What are cold sores?

Cold sores are small blisters caused by the herpes simplex virus (HSV). There are two types. Herpes simplex type 1 most often causes cold sores on and around the lips and face, and herpes simplex type 2 more often causes genital herpes, although either type can affect either area.

After the first infection, the virus stays in the body for life, lying dormant in the nerves close to where it was caught. From time to time it can reactivate and travel back along the nerve to the skin, causing a new outbreak in the same area.

Who gets them?

Herpes simplex infection is very common, and many people catch the virus in childhood. Some people never have symptoms, while others have repeated outbreaks. How often cold sores come back varies greatly, from several times a year to rarely or never.

What causes them?

Cold sores are caused by the herpes simplex virus. Outbreaks can be triggered by colds, flu and other illnesses, tiredness, sun exposure, stress, injury to the skin and, in some women, periods.

Are they hereditary or contagious?

Herpes simplex is not hereditary. It is infectious and passes on through skin contact with an active sore, kissing being a typical example. It can occasionally spread during the tingling or itching phase before a sore appears, and less often when there are no symptoms at all. You will not catch it from towels, pools, saunas or toilet seats. Genital herpes is passed on through sexual contact, including oral sex, usually when sores are present.

What do they look and feel like?

The first infection usually appears 2 to 14 days after contact and can be more severe than later outbreaks, sometimes with fever, swollen glands and sore gums or mouth.

A typical outbreak starts with tingling, itching, burning or pain in the skin. Over the next day or two, small, fluid-filled blisters appear in a cluster. These burst to form shallow sores, which then dry out and crust over. Most outbreaks heal within 7 to 10 days without scarring.

Cold sores most often affect the lips and the skin around the mouth and nose, but they can occur anywhere on the face or body.

Complications

People with eczema can develop a widespread, painful infection called eczema herpeticum, which needs urgent medical assessment. Herpes simplex can also spread to the eye, causing pain, redness and discharge, and can cause scarring of the eye if not assessed promptly. Older people, people who are very unwell and those with a weakened immune system are at higher risk of more severe infection.

How are they diagnosed?

Cold sores are usually diagnosed from their appearance. If there is any doubt, a swab can be taken from a blister to confirm the virus, with results usually available within a few days.

What are the treatment options?

Identifying the cause is the key to treating contact dermatitis, and Dr Mounsey carries out patch testing to find any allergens responsible. Where irritation is the main problem, he will advise on reducing exposure and protecting the skin. Flares are treated with emollients and topical corticosteroids, and you will be given written information on any allergen found, including where it is commonly hidden and the names it may appear under on product labels. Once the trigger is avoided, many people see a marked improvement.

What is the outlook?

The virus remains in the body for life, but most people have mild or infrequent outbreaks. Only a small number of people have troublesome, frequent recurrences.

More information

British Association of Dermatologists patient leaflet: https://www.bad.org.uk/pils/herpes-simplex

British Association of Dermatologists patient leaflet on eczema herpeticum: https://www.bad.org.uk/pils/eczema-herpeticum

This page gives general information only and is not a substitute for a consultation. Everyone's skin is different, and what is right for you will depend on your own circumstances. If you are worried about a skin problem, please book an appointment with Dr Mounsey or speak to your GP. If you have a mole or skin lesion that is changing, bleeding or growing quickly, please seek medical advice promptly.