Herpes labialis is caused by the herpes simplex virus, which leads to small fluid-filled sores or blisters developing in and around the mouth. Symptoms usually begin with a burning or tingling sensation in the corners of the mouth and the blisters have usually cleared up within 7 to 10 days.
Cold sores usually resolve independently but several treatments are available to help ease symptoms and accelerate recovery.
Topical antiviral creams that slow multiplication of the virus and therefore progression of the infection are available. These can be bought over the counter. The antiviral agent should be applied as soon as symptoms first present (e.g. when tingling is felt around the mouth) because the treatment is not effective if it is applied after this initial stage. Examples of antiviral creams include acyclovir and penciclovir. It may be necessary to apply the cream up to five times a day, for four to five days.
For severe cases of herpes labialis, antiviral tablets may be prescribed as these are generally more effective at treating cold sores.