Zylovir Adverse Reactions

Renal impairment may be associated with systemic use of aciclovir in some patients; it is usually reversible and is reported to respond to hydration and/or dosage reduction or withdrawal, but may progress to acute renal failure. The risk of renal toxicity is increased by conditions favouring deposition of aciclovir crystals in the tubules such as when the patient is poorly hydrated, has existing renal impairment, or when the drug is given at a high dosage. Some patients receiving systemic aciclovir may experience transient increases in blood concentrations of urea and creatinine although this is more acute with intravenous administration.
Occasional adverse effects after systemic administration include increased serum bilirubin and liver enzymes, haematological changes, skin rashes (including erythema multiforme, Stevens-Johnson syndrome, and toxic epidermal necrolysis), fever, headache, dizziness, and gastrointestinal effects such as nausea, vomiting, and diarrhea. Anaphylaxis has been reported. Hepatitis and jaundice have been reported rarely. Neurological effects including lethargy, somnolence, confusion, hallucinations, agitation, tremors, psychosis, convulsions, and coma have been reported in a small number of patients, particularly in those given intravenous aciclovir and with predisposing factor, such as renal impairment; these effects may be more marked in older patients. Thrombotic thrombocytopenic purpura and hemolytic uraemic syndrome, sometimes resulting in death, have occurred in immunocompromised patients given high parenteral doses of aciclovir. Accelerated diffuse hair loss has also been reported.