Vesicular eruptions following acyclovir administration

OBJECTIVE: To report the occurrence of vesicular lesions on the skin of a child receiving intravenous acyclovir therapy. CASE SUMMARY: A 12-year-old boy with presumed herpes simplex encephalitis developed cutaneous vesicular lesions following intravenous acyclovir administration. The lesions were initially thought to be herpetic. Further evaluation of the vesicle fluid and the temporal relationship of the development of the lesions with acyclovir administration led to the conclusion that the reaction was drug induced. DISCUSSION: Although inflammation and phlebitis are fairly common after acyclovir infusion, the development of vesicular lesions appears to be rare. Only two cases, both in adults, have been published in the medical literature. Although several theories have been proposed, including hypersensitivity, local drug toxicity, and tissue damage associated with extravasation, the mechanism of this reaction remains unclear. CONCLUSIONS: Vesicular eruption is a rare adverse reaction in patients receiving acyclovir. Careful evaluation is necessary to differentiate this reaction from herpetic lesions.