ABSTRACT Antiretroviral therapy (ART) has modified the outcome of patients with HIV infection, providing virological control and reducing mortality. However, there are several reasons as to why patients may discontinue their antiretroviral therapy, with adverse events being one of the main reasons reported in the literature. This is a case-control nested in a cohort of people living with HIV/AIDS, conducted to identify the incidence of ART modification due to adverse events and the associated factors, in two referral services in Recife, Brazil, between 2011 and 2014. Of the modifications occurred in the first year of ART, 25.7% were driven by adverse events. The median time elapsed between initiating ART and the first modification due to adverse events was 70.5 days (95% CI: 26-161 days). The main adverse events were dermatological, neuropsychiatric and gastrointestinal. Dermatological events were the earliest to appear after initiating ART. Efavirenz was the most prescribed and most modified drug during the study period. The group of participants who used zidovudine, lamivudine, and efavirenz had a 2-fold greater chance (adjusted OR: 2.16 95% CI: 1.28-3.65) of switching ART due to adverse events when compared to the group that used tenofovir with lamivudine and efavirenz.