Adverse Effects of Macrolides Main concerns with macrolides include Gastrointestinal (GI) disturbances (mainly with erythromycin) QT-interval prolongation Inhibition of hepatic metabolism, leading to numerous drug interactions Erythromycin commonly causes dose-related GI disturbances, including nausea, vomiting, abdominal cramps, and diarrhea; disturbances are less common with clarithromycin and azithromycin.