What is a cold sore?
A cold sore is a viral infection of the skin on or near the lips. The complaints typically begin with local itch and burning of the skin. The skin swells, becomes red, and then small blisters develop. After a few days the blisters dry into crusts, and after about 10 days the lip has healed completely. Characteristic of a cold sore is that it returns with some regularity — and typically in the same place.
What is the cause?
The infection is caused by the herpes simplex virus. Infections with this virus are very common. Two herpes simplex viruses (HSV) are distinguished; cold sores are mainly caused by HSV type 1, while HSV type 2 is mainly known as the cause of genital herpes.
The herpes virus in a cold sore is very contagious. The virus is present in the blisters and the fresh crusts and can be transmitted by kissing or other bodily contact, so the eye or the genitals can also become infected. Once the skin has healed, the virus can no longer be transmitted. The virus hides in the nerve pathways of the skin and can strike again from this hiding place; because it keeps withdrawing into the same nerve, the cold sore typically returns in the same place. Triggers for recurrences include a fall in resistance, illness (fever) and sunburn.
Is a cold sore dangerous?
A cold sore is troublesome and painful but is in principle not dangerous for the person who has it. For babies, however, a herpes infection is very dangerous and sometimes even fatal. Avoid physical contact with a baby when you have a cold sore. If you regularly have cold sores, you must even be very cautious about cuddling and kissing newborn babies during periods when you have no blisters, because infectious virus can very probably be produced in the skin not only during a cold sore but also in the time before one appears and becomes visible. If you are pregnant or have a newborn baby and also develop cold sores regularly, it is wise to tell your doctor.
Besides a cold sore, herpes infections can also trigger other skin conditions that are not directly caused by the virus but are a reaction to its presence in the body. An important example is erythema multiforme, with red spots and sometimes even blisters, which disappears again once the herpes infection has settled.
How is a cold sore treated?
- A cold sore heals on its own in principle.
- Do not touch the cold sore in the active stage; via the fingers you can infect others and yourself (for example the genitals).
- Prevention is better than cure: keep your resistance optimal and avoid sunburn.
- At a very early stage you can sometimes nip the cold sore in the bud by applying an antiviral cream (for example creams containing aciclovir or penciclovir), applied several times a day for 4 to 5 days. Stopping the cold sore does not always succeed.
- A cream containing zinc sulphate can be used from an early stage and may limit the number of blisters; once the cold sore has appeared, zinc-sulphate cream can also be applied, as zinc relieves itch and dries the blisters, and can be used until they have dried up.
When to see a doctor
See a doctor if cold sores are very frequent or severe, if a sore is near the eye, if you have eczema, or if you are pregnant or in close contact with a newborn baby.