Anticholinergic drug: Concomitant use may potentiate anticholinergic effect.
Beta blockers: Concomitant use may inhibit bronchodilating effects. Severe bronchospasms may be produced in asthmatic patients.
Methyldopa: Concurrent administralion may result in an increased pressor response.
MAO inhibitors: Coadministration may result in severe headache, hypertension, and hyperpyrexia, resulting in hypertensive crisis. MAO inhibitors also potentiate the actions of beta-adrenergic agonists on the vascular system. Avoid coadministration with sympathomimetics or within 2 weeks.
Tricyclic antidepressants (TCAs): TCAs potentiate the pressor response of direct-acting sympathomimetics; dysrhythmias have occurred.
Theophylline: Enhanced toxicity, particularly cardiotoxicity, has been noted. Decreased theophylline levels may occur.