Acyclovir is a drug which inhibits herpes simplex virus replication and has been used extensively in individuals with herpes infections, regardless of the site of infection. It has been shown to be effective in the long term suppression of recurrences in adults with frequently recurring genital herpes8 and has been used parenterally in high doses for neonatal herpes infection. There have been no reports of serious short term toxicity associated with oral administration or with intravenous infusion as long as there is adequate hydration9. There is also no evidence of teratogenicity of acyclovir given in pregnancy