Ilosone is an antibiotic which is often generically prescribed as erythromycin and is a member of the family of drugs known as macrolide antibiotics. Ilosone has been known to produce heart related life threatening events in patients who are simultaneously taking medications such as cisapride, pimozide, terfenadine, or astemizole. Ilosone has also been associated with severe diarrhea that will present with bloody or watery stools. Patients should be advised that this could be a sign of a new infection and should contact the prescribing physician instead of taking anti-diarrhea medications.