Atazanavir/Ritonavir-Associated Erythema Multiforme in an HIV-1-Positive Patient.

We report a case of erythema multiforme (EM) associated with atazanavir/ritonavir in a patient with HIV-1 infection. The patient was receiving tenofovir, lamivudine, and dolutegravir; however, owing to a supply chain issue, dolutegravir was substituted with atazanavir/ritonavir. The patient subsequently developed pruritic erythematous papules and plaques with characteristic target lesions over the face and a hemorrhagic crust on the lower lip, without epidermal detachment or systemic symptoms. The Naranjo probability score indicated a probable adverse drug reaction. This case highlights the importance of recognizing EM as a potential adverse reaction to atazanavir and of early drug withdrawal to prevent progression to more severe cutaneous adverse reactions, including Stevens-Johnson syndrome.