Cold sores

Cold sores are caused by the herpes simplex virus. They occur in people who have been infected with the virus in the past, usually as a child. The virus lies dormant in the nerve cells which supply feeling to the skin. Intermittently it tracks down these nerves and causes a blister on the lips or other facial areas.

The initial symptoms are usually a ‘tingling’. A blister then appears which scabs over. Most cold sores last for about 5-7 days. They usually appear when the individual’s immune system is run down, eg when suffering a cold or some other infection, or if they are tired and stressed. Some people find that exposure to the sun brings on an attack.

Treatment can be purely symptomatic, using creams to ease the discomfort, or you can apply an antiviral cream which is available over the counter. It needs to be applied as soon as the symptoms start. If the cold sores are very troublesome and frequent, antiviral tablets may be another option, see your doctor to discuss this.

The blister contains particles of the virus so it is probably a good idea not to kiss while you have a cold sore. It is possible to infect the genital area with herpes if you have oral sex. You may continue to shed virus for a couple of weeks after the infection. For more information

Further information


This article published on
25 November 2005

Next review date 11/1/2013


Skin, hair and bones
First aid

Areaof the body

Immune system

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