Dertli, BulentGuzel Karahan, SenaKoseoglu, KadirCakir, AhmetSalduz, Ekrem2026-04-042026-04-0420252047-99562047-9964https://doi.org/10.1136/ejhpharm-2025-004705https://hdl.handle.net/11616/109066Viral encephalitis is a hazardous central nervous system disorder requiring immediate antiviral intervention. Acyclovir is the standard treatment for herpes simplex virus (HSV) encephalitis; nevertheless, improper dosing or administration can lead to nephrotoxicity and neurotoxicity. This case describes a 54-year-old male patient admitted for an allergic reaction, who thereafter had incoherent speech, instability and involuntary motions suggestive of HSV encephalitis. Intravenous acyclovir treatment was initiated empirically following cerebrospinal fluid examination. On the third day of therapy, the patient exhibited acute renal impairment, accompanied by hallucinations and significant psychomotor agitation. Following the clinical pharmacist's recommendations, the dosage was adjusted and the infusion period was prolonged to at least 1 hour, predicated on an estimated glomerular filtration rate of 20 mL/min/1,73 m(2). Subsequent to these surgeries, renal function and neurological status steadily enhanced, enabling a successful resolution of treatment. This example highlights the crucial role of clinical pharmacists in reducing acyclovir-related toxicities via personalised dosage and infusion management.eninfo:eu-repo/semantics/closedAccessAcyclovircase reportDRUG-RELATED SIDE EFFECTS AND ADVERSE REACTIONSAcute Kidney InjuryNeuropathologyArticle4147579510.1136/ejhpharm-2025-0047052-s2.0-105027390105Q1WOS:001655698500001Q40009-0001-5856-6723