Erythromycin is a macrolide antibiotic that inhibits bacterial protein synthesis and is effective against the same organisms as penicillin G. The drug is commonly used to treat community-acquired pulmonary infections in penicillin-allergic patients. Erythromycin also has prokinetic effects on the gastrointestinal system. At low doses, erythromycin induces activity in the gastric antrum, which propagates to the small intestines. At higher doses, erythromycin induces a prolonged period of antral activity by stimulating motilin receptors to accelerate gastric emptying. Although transplant recipients frequently suffer from opportunistic bacterial infections and/or gastrointestinal dysmotility, erythromycin should not be given to recipients taking FK506 (tacrolimus, Prograf) or cyclosporine.