Cold sores are small blisters in or near the lips. Herpes labialis is the medical name for cold sores. The herpes family of viruses causes a wide range of disorders including chicken pox and shingles. There are two types of Herpes Simplex infection
Herpes Simplex Virus 1 and Herpes Simplex Virus 2. Cold sores are caused by Herpes Simplex 1. Herpes Simplex Virus 2 causes predominantly genital herpes.
Symptoms
Initially there is a tingling sensation on or near the lip, which is followed by a painful red sore that subsequently blisters. After a while it crusts over and finally disappears. Cold sores do not cause scarring.
In rare circumstances the infection can spread to the inside of the mouth, the gums, the brain and the eyes.
Symptoms of herpes infection in the mouth (called 'stomatitis') and gums (called 'gingivitis') include:
- Burning sensation in the mouth
- General malaise
- Fever
- Blisters in the mouth which may progress to ulcers
- Difficulty eating
- Enlarged lymph glands in the neck which may be painful
Symptoms of herpes infection in the brain (called 'encephalitis') include:
- Headache
- Fever
- Odd behaviour
- Coma
Symptoms of ocular herpes (in the eyes) include:
- Marked pain in the eye
- Visual impairment
How do you get cold sores?
Cold sores are spread by physical contact with an infected person. This contact can include kissing or sharing food which has been bitten into by the infected person. The incubation period is 1- 26 days.
If you have a cold sore on your lip avoid touching the eyes with your hands as there is a risk of ocular herpes which can cause scarring of the cornea. Wash your hands regularly.
Herpes simplex virus occurs throughout the year. Once the infection is caught, it remains in the body for life, residing in nerve endings. The initial infection may go unnoticed and cause no symptoms. It will remain asleep (dormant) in the nerve endings until awoken (reactivated). In some people the infection remains dormant forever, whereas in others it is reactivated every now and then to cause cold sores.
Recurrent infections occur in about one third of people who get infected with the virus. Menstruation, exposure to ultra violet light, illnesses associated with a fever, and trauma to the skin are all associated with reactivation. Immunosuppression (suppression of the immune system resulting from chemotherapy, corticosteroids or infection with HIV) can also be associated with the recurrence of cold sores.
Diagnosis and treatment
Diagnosis is usually made clinically by the doctor who can identify the blisters. However a sample of the blisters might be sent to the laboratory for identification of Herpes Simplex 1. In the case of encephalitis (infection in the brain) a sample of the spinal fluid may be sent for analysis.
Treatment of cold sores
The infection itself is self limiting, resolving in 7 to 10 days. There are anti-viral creams (e.g. Acyclovir cream) available which are designed to delay the onset of the blisters. However these creams need to be applied as soon as the tingling starts in order to gain maximum benefit. If the cold sore is painful a mild pain-relieving tablet can be taken.
Treatment of other herpes infections
Treatment of stomatitis, encephalitis, ocular herpes includes the prescription of anti-viral medications that act to prevent the spread of the herpes virus. Acyclovir is the agent commonly used. It can be given in tablet form or, when there is a more severe infection, it can be given into a vein (intravenous). Eye drops containing the anti-viral agent can be applied to the eye.
