TREATMENTS

Aciclovir
€¢ Aciclovir is a synthetic analogue of guanine; its spectrum of activity is specific to human pathogenic viruses that produce thymidine kinase, of which HSV-1 is one. It is converted by thymidine kinase within viral cells to aciclovir triphosphate, which is then incorporated into viral DNA instead of the deoxyguanosine triphosphate required for DNA synthesis and replication.
€¢ It is presented as a 5% cream. It is applied five times daily, at 4-hourly intervals starting, if possible, as soon as prodromal symptoms occur. Treatment can be continued for up to 10 days, if necessary. Aciclovir cream is licensed for use in children and pregnant women.
€¢ Evidence of the effectiveness of topical aciclovir has not been convincing, but it may shorten attacks by a day or two if use is begun early enough.1

Docosanol
€¢ Docosanol is a saturated fatty acid. It has antiviral activity although its exact mode of action is unknown. In vitro studies have shown that it affects the fusion between the HSV-1 virus and the plasma membrane of the human host cell, inhibiting intracellular uptake and replication.
€¢ Docosanol is presented as a 2% cream. It is applied 3-hourly during waking hours (5 times daily), for up to a maximum of 10 days. It is licensed for use from age 12 and in pregnant women.
€¢ In a clinical trial, docosanol cream produced a reduction in time to healing only marginally greater than placebo.2

Other preparations
Products containing combinations of local anaesthetics, counterirritants, antiseptics and astringents, are marketed to reduce discomfort and promote faster healing of sores while the infection takes its course. Some are formulated with alcoholic bases, which may have a drying effect on sores and speed up healing. The bland cream bases of some products may have a soothing effect. Combination preparations for cold sores are relatively innocuous. Creams can be applied as frequently as necessary, although lotions and gels are limited to three or four applications per day.