A 51-year-old woman with human immunodeficiency virus (
HIV) infection and
end-stage renal disease arrived at the emergency department (ED) with a diffuse
rash on the chest and back; she was diagnosed with
varicella-zoster virus infection, received one dose of i.v.
acyclovir, and was discharged home with a prescription for
valacyclovir. After taking one dose of the
drug, she became confused and agitated. The next day the patient returned to the ED; she was confused and unresponsive, with signs and symptoms suggesting
viral encephalitis. After a workup including lumbar puncture fluid, she was treated empirically with i.v.
acyclovir for
viral encephalitis. Within one hour of receiving the
acyclovir infusion, the patient developed
angioedema of the lips, tongue, and periorbital areas requiring intubation and transfer to the intensive care unit. Further
acyclovir therapy was withheld, and
foscarnet therapy was initiated for the presumptive treatment of
viral encephalitis. Over the next few days, the patient's
angioedema completely resolved; her mental status gradually improved while she completed a 14-day course of
foscarnet therapy. The application of the Naranjo scale indicated a probable adverse reaction to
acyclovir, likely mediated by
acyclovir-specific
immunoglobulin E, highlighting the need to consider alternative
antiviral agents without cross-reactivity to
acyclovir in patients with confirmed or suspected
viral encephalitis.
CONCLUSION: