by First Year Chemistry Student Ben Marsh, St. Edmund Hall, University of Oxford, images and models by Karl Harrison

Acyclovir is a drug used for the treatment of several conditions. It is available over the counter in the UK under the brand name Zovirax, in a cream form marketed by Glaxo-Wellcome.

This cream is used for the treatment of cold sores, normally facial.

Prescribed, it is also used to treat chicken pox, shingles and other forms of herpes (cold sores being the facial form). For these purposes it is used in the form of tablets, capsules or a suspension.

The topical form has no serious side effects and can be used in almost all cases.

The ingested forms can lead to some side effects, which include rash, itching, fatigue, headache, diarrhea, nausea and vomiting. This is a somewhat nasty list, but these side effects are unlikely, and with the exception of rash and itching are not serious. It may also affect the menstrual pattern.

It is recommended that pregnant women take it only for life threatening herpes simplex, although there is no evidence to suggest that acyclovir causes any problems with the development and birth of the baby. It will also pass into breast milk, so use whilst breast-feeding is not recommended.

There are no problems using acyclovir with most other medications, and it can be used by people suffering from diabetes and asthma.

It can be used without regard for alcohol, sun exposure or food, and whilst driving/operating machinery.