Enhances effects of antihypertensives; β-blockers, Rauwolfia causes bradycardia; increases blood conc of carbamazepine & digoxin; nitrates, dihydropyridine Ca antagonist, antiarrhythmic drug, apridin HCl, theophylline, cyclosporin, tacrolimus, phenytoin, triazolam, midazolam, cimetidine, HIV protease inhibitor, rifampicin, anesth, & muscle relaxant.