Beta Blockers: Although the results of a clinical study did not indicate a safe problem associated with the administration of D.H.E. 45  (dihydroergotamine mesylate) Injection, USP to subjects already receiving propranolol, there have been reports that propranolol may potentiate the vasoconstrictive action of ergotamine by blocking the vasodilating property of epinephrine.
<propranolol, effect, ergotamine>