MAY POTENTIATE ACTION OF CARBAMAZEPINE, CYCLOSPORIN, THEOPHYLLINE, WARFARIN, HEXABARBITAL, TRIAZOLAM(BENZODIAZEPINES) . INCREASES SERUM DIGOXIN LEVELS, REDUCES THERAPEUTIC EFFECT OF PENICILLINS, TERFENADINE AND ASTEMIZOLE. INCREASES THE RISK OF THE ADVERSE EFFECT ON THE HEART. ERGOTAMINE OR DIHYDROERGOTAMINE HAS BEEN ASSOCIATED IN SOME PATIENTS WITH ACUTE ERGOT TOXICITY CHARACTERIZED BY SEVERE PERIPHERAL VASOSPASM AND DYSESTHESIA. PATIENTS RECEIVING CONCOMITANT LOVASTATIN AND ERYTHROMYCIN SHOULD BE CAREFULLY MONITORED; CASES OF RHABDOMYOLYSIS HAVE BEEN REPORTED IN SERIOUSLY ILL PATIENTS. ERYTHROMYCIN SHOULD NOT BE GIVEN WITH OTHER DRUGS THAT PROLONG THE QT INTERVAL DUE TO THE INCREASED RISK OF PRECIPITATING VENTRICULAR ARRHYTHMIAS. THESE DRUGS ARE AMIODARONE, DISOPYRAMIDE, PROCAINAMIDE, OR QUINIDINE, PHENOTHIAZINE ANTIPSYCHOTICS, TRICYCLIC ANTIDEPRESSANTS, ANTIHISTAMINES, ASTEMIZOLE AND TERFENADINE, HALOFANTRINE, PENTAMIDINE, SULTOPRIDE, OR VINCAMINE AND DIURETICS