Rare Case of Valacyclovir Toxicity Reported in Elderly Woman with Single Kidney

The patient’s neuropsychiatric symptoms and renal dysfunction raised suspicion for valacyclovir toxicity. The antiviral was discontinued, and the patient was closely monitored throughout her hospitalization. There was a gradual improvement in renal function, accompanied by a resolution of the neurotoxic symptoms.

The authors highlighted that while nephrotoxicity associated with valacyclovir is uncommon, it can occur through mechanisms such as crystal-induced tubular obstruction, tubular dysfunction, or tubulointerstitial nephritis. Notably, this case is unique because the adverse effects occurred despite standard dosing and in the absence of known overdose. The presence of a solitary kidney may have rendered the patient particularly vulnerable to these complications.

Dr. Badran and the team emphasized the diagnostic challenge in such scenarios, especially when a renal biopsy is not feasible due to the risks associated with a single kidney. In such cases, a detailed medication history and clinical assessment are vital for timely identification and intervention.

The case emphasizes the need for heightened vigilance when prescribing valacyclovir to patients with compromised renal function or a history of nephrectomy. Clinicians are urged to consider drug-induced toxicity when encountering AKI or neurological symptoms in this patient population.

The authors recommend that further large-scale retrospective studies or meta-analyses be conducted to explore potential dose-related toxicity patterns of valacyclovir, particularly in patients with reduced renal reserve. Early recognition and withdrawal of the offending agent remain key to preventing long-term complications.

Reference:

Badran, S., Li, S., Nguyen, S. et al. Valacyclovir-induced neurotoxicity and nephrotoxicity in an elderly patient with a history of nephrectomy: a case report. BMC Nephrol 26, 269 (2025). https://doi.org/10.1186/s12882-025-03941-7