Abstract
Efavirenz is a non-nucleoside reverse transcriptase inhibitor widely used in HIV treatment. Although generally well-tolerated, rare cases of severe hepatotoxicity have been reported. We present a case of a patient on efavirenz-based highly active antiretroviral therapy who developed jaundice and marked transaminitis 1 year after initiation. Infectious, autoimmune, and toxic causes were ruled out, and genetic testing revealed no metabolic abnormalities. Treatment involved corticosteroids, immunosuppressants, and switching to dolutegravir, leading to resolution. This is the first documented case in the Philippines of delayed-onset efavirenz-induced liver injury, underscoring the importance of ongoing liver monitoring during antiretroviral therapy.