HERPES labialis, also known as “cold sore” or “night fever”, is a skin condition characterised by unsightly and socially embarrassing sores and/or vesicles, which are groups of blisters, on a person’s lip.

It has been shown to affect up to one-third of the population in the USA and as much as nine out of every 10 students in some colleges.

It is caused by the herpes simplex virus-type 1, which was typically described as herpes infection “above the waist” to differentiate it from herpes simplex virus-type 2 or genital herpes. However, with the increased prevalence of oral sex, genital herpes is now being found on the lips and other areas of the face. They can now be differentiated by a simple blood test that checks for antibodies from both strains.

The first appearance of the lesion on the lip is usually in the form of papules or bumps on an erythematous or red base, which progresses to vesicles. After three to four days, an ulcer is formed; this becomes crusted then heals completely in two weeks.

Night fever may also be found on the cheeks, around the mouth, in the nasal mucosa, on the tongue, gums, or in the throat. A prodrome may precede the skin lesions by up to 24 hours, and is usually in the form of tingling, numbness, redness, itching, or burning in the areas to be affected.

It is usually spread by kissing, oral contact, close personal contact, or any act which results in the transfer of saliva containing the shedding virus. It is often triggered when the individual is under stressful conditions, during illness, fever, surgery, dental procedures, lip tattooing, sun exposure, and menses. The recurrent attacks are usually shorter and milder, unless the person is immunocompromised such as patients with HIV, organ transplant recipients or on haemodialysis. It is also possible to spread the virus without having the skin lesion.

There is no cure for herpes labialis. The virus remains in the infected person, residing dormant in the nervous system. Reactivation occurs when the immune system is challenged or the body is under stressful conditions.

It is treated by oral antiviral drugs such as Valacyclovir or Acyclovir and topical creams such as Docosanol, which reduce the duration of the illness, helps the sore to heal more quickly, and can reduce the frequency of recurrences.

Preventing the transmission of the virus is done by not touching the person with an active outbreak site, not sharing utensils or coming into close contact with the infected person.

Dr Romayne Edwards is a consultant emergency physician at the University Hospital of the West Indies and an associate lecturer at the University of the West Indies.