We performed a retrospective study to evaluate, under routine circumstances, the tolerance and immunovirological changes associated with antiretroviral regimens that contain nevirapine in 137 patients (88% were antiretroviral experienced). During a mean follow-up of 11 months, 33% of patients reported side effects attributed to nevirapine, and 21% discontinued treatment because of poor tolerance. Administration of antihistamines or corticosteroids at the initiation of treatment was not protective against adverse events (relative risk, 0.82; 95% confidence interval, 0.49-1.38). The proportion of patients with hepatitis C virus (HCV) and/or hepatitis B virus (HBV) coinfection who had alanine aminotransferase levels of >100 IU/L increased from 19.4% at baseline to 42.9% at month 12 of follow-up (P=.02). We noticed a significant increase of the proportion of patients with total cholesterol levels of >5.5 mM (P=.02). We have shown that there is a high level of discontinuation of nevirapine therapy in clinical practice and that side effects were not prevented by administration of antihistamines or corticosteroids. Coinfection with HCV or HBV increased the risk of hepatotoxicity, which lead to the cautious use of nevirapine for such patients.