Pregnancy: A post-marketing Acyclovir pregnancy registry has documented pregnancy outcomes in women exposed to any formulation of Acyclovir. The registry findings have not shown an increase in the number of birth defects amongst Acyclovir exposed subjects compared with the general population, and any birth defects showed no uniqueness or consistent pattern to suggest a common cause. Systemic administration of Acyclovir in internationally accepted standard tests did not produce embryotoxic or teratogenic effects in rabbits, rats or mice.
In a non-standard test in rats, fetal abnormalities were observed but only following such high subcutaneous doses that maternal toxicity was produced. The clinical relevance of these findings is uncertain.
The use of Acyclovir cream should be considered only when the potential benefits outweigh the possibility of unknown risks however the systemic exposure to Acyclovir from topical application of Acyclovir cream is very low.
Teratogenicity: Effects in non-clinical studies were observed only at exposures considered sufficiently in excess of the maximum human exposure to indicate little relevance to clinical use.
Breastfeeding: Limited human data show that the drug does pass into breast milk following systemic administration. However, the dosage received by a nursing infant following maternal use of Acyclovir cream would be insignificant.
Fertility: There is no information on the effect of Acyclovir on human female fertility.
In a study of 20 male patients with normal sperm count, oral Acyclovir administered at doses of up to 1 g per day for up to six months has been shown to have no clinically significant effect on sperm count, motility or morphology.