Aciclovir desensitisation and rechallenge

A 29-year-old patient with HIV developed a facial angioedema hypersensitivity reaction to aciclovir when treated for acute retinal necrosis secondary to a herpes virus infection. She developed a similar reaction to famciclovir. Successful rapid desensitisation with oral aciclovir was performed and she became tolerant to aciclovir. She successfully completed 28 months of continuous treatment with no further reactions. However, 28 months later she experienced blurred vision and resumed taking oral aciclovir without a preceding desensitisation regimen. No allergic reaction occurred.