Cold Sores

Cold sores on the lips of the mouth are caused by a virus called Herpes simplex. This virus, once established in the skin, will never be removed. It lives in the nerves of the cold sore sufferer, most of the time without any signs of being present at all. However certain factors may cause the virus to enter its reproductive cycle and this is what we see as the cold sore.

Several factors may cause a cold sore to form, for example ultraviolet light may start a cold sore. This may be from strong sunlight on a holiday or even a sunbed. Other causes are physical and emotional stress, other illnesses such as colds or 'flu may also encourage a cold sore to form. Women may also find that they get cold sores during or just before menstruation (period).

The development of a cold sore has several stages:

  • Tingle Stage - the skin tingles and itches before the sore appears
  • Blister Stage - a small patch of skin raises and forms a blister
  • Weeping Stage - the blister bursts to form a weeping sore
  • Scab Stage - natural healing occurs at the site of the sore
About 12 million people in the UK get cold sores usually between 1 and 3 times a year although sometimes up to 12 sores in a year. However it is usual for a cold sore to only last about 10 days.


There are several treatments available to ease the symptoms of cold sores. These are usually lip ointments applied to the sore to dry it out at the weeping stage. There is now also a newer treatment based on the antiviral drug aciclovir. This treatment is to be used at the tingle stage and acts to prevent the reproduction of the virus and so stop the formation of the sore. It must be applied early to be effective, it only reduces the severity of the sore once the sore is formed.

The types of preparations listed above should not be used on genitals or eyes, in this case you should consult a doctor.

General Points

There are several things that you should avoid doing while you have a cold sore, the virus that causes the sore is highly contagious and can be passed on extremely easily.
  • Avoid touching the sore, if you do touch it wash your hands well to prevent spreading the infection to other areas of your mouth or to other people.
  • Do not kiss anyone while you have a cold sore, this will inevitably pass on the virus.
  • Do not touch the eyes or genitals of yourself or another person if you think you have touched your cold sore. This will again prevent spreading of the virus.

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