Neurotoxicity from acyclovir and valacyclovir in patients undergoing peritoneal dialysis: Still rare, but still present

Acyclovir and valacyclovir have been widely used for the treatment of herpes virus infections, including herpes zoster, with generally favorable outcomes. However, in patients with chronic kidney disease, particularly those undergoing peritoneal dialysis or hemodialysis treatment, neurotoxicity can be a significant complication as renal excretion is the primary elimination pathway. Here, we report three cases of automated peritoneal dialysis patients treated for herpes zoster who developed neurotoxicity following acyclovir or valacyclovir administration. Symptoms appeared 2 to 4 days after treatment initiation. They included mental confusion, psychomotor agitation, dizziness, dysgeusia, anosmia, blurred vision, gait instability, hallucinations, dysarthria, paresis, involuntary lower-limb movements, ataxia, and anorexia. Neurological symptoms gradually resolved after drug discontinuation, alongside complete regression of zoster lesions. Despite decades of clinical experience and numerous reports, acyclovir and valacyclovir-induced neurotoxicity continue to occur in patients with severe renal impairment. This report underscores the importance of dose adjustment and close monitoring, emphasizing that neurotoxicity, although rare, can occur even at apparently safe doses in patients undergoing peritoneal dialysis.