Cold sores are a common skin infection, usually around the nose or mouth, caused by the virus Herpes simplex type 1.
Initially, the infection is caught as a child, when it is a simple mouth infection. The virus then migrates to the nerve endings around the lips and nose, and remains inactive there for many years. It may later reactivate at times of stress or illness to cause cold sores.
It is passed from one person to another by direct contact (e.g. kissing). Sixty percent (60%) of the population are infected and remain carriers throughout their lives.
Sores are uncommon before five years of age, and the incidence decreases in old age. Recurrences tend to develop at the same spot.
Active infection is characterised by redness and soreness of the affected area, followed a day or two later by an eruption of small blisters, which rapidly burst to leave a shallow, weeping, painful ulcer. In severe cases, there may be a mild fever, and the lymph nodes in the neck may become tender and enlarged. An additional bacterial infection is the only common complication.
If necessary, the diagnosis can be confirmed by taking special swabs from the sore.
If treated by appropriate antiviral creams and lotions (e.g. aciclovir, idoxuridine, penciclovir) immediately the redness and discomfort is felt and before the blisters form, it may be possible to stop further progress. Once the cold sore is established, a cure is not normally possible, but drying, antiseptic and anaesthetic creams or lotions may be used.
Patients who are severely affected on a regular basis may use expensive aciclovir or famciclovir tablets continuously to prevent infections.
The sore heals and the pain eases in about a week. Some patients have only one attack of cold sores in their lives, while others develop one every month. Over many years, most patients find that their attacks become less frequent.