Dermatologic adverse drug reactions (ADRs) to non-nucleoside reverse transcriptase inhibitors (NNRTIs) are common in HIV patients. Efavirenz-induced rash occurs in 10%-34% of cases, limiting its use in hypersensitive patients. Although desensitization protocols to Cotrimoxazole and Penicillin are well-known, such regimes are rarely described for Efavirenz. We present a seven-day desensitization protocol in two HIV-positive patients

Two HIV+, HCV+ injecting drug users (IDUs) developed skin rash 6 and 7 days, respectively, after starting antiretroviral (ARV) therapy, comprising Didanosine, Lamivudine and Efavirenz. Both had moderate immune suppression with CD4 cell counts/mm3 of 230 and 270, and elevated plasma viral loads of 28,000 and 300,000 copies/ml, respectively. Patients were treated with Fexofenadine without improvement. ARVs were discontinued and the rash disappeared. Didanosine and Lamivudine were reintroduced successfully, but 200 mg Efavirenz rechallenge caused a rash in both. A seven-day desensitization protocol was undertaken, starting with 50 mg Efavirenz and gradually increasing the daily dose to a maximum of 600 mg at day 7.

No cutaneous ADRs were observed during or following the desensitization procedure. Efavirenz therapy has been continued 8 and 10 months later, and the clinical course has improved steadily in both.

ADRs may limit the choice of ARVs. Efavirenz is the only NNRTI currently available once daily, thereby most suitable for IDUs. “Treating through” and antihistamines were not options for these patients. Every effort should be made to allow the continued use of Efavirenz that otherwise would be restricted. A simple seven-day protocol may be useful when other interventions have failed.