Verapamil, diltiazem, amiodarone, digoxin (additive bradycardia/heart block), clonidine (rebound hypertension on withdrawal), insulin/oral antidiabetics (masks hypoglycemia), NSAIDs like ibuprofen (may reduce BP-lowering effect), other antihypertensives, bronchodilators (reduced effect), SSRIs like fluoxetine/paroxetine (may increase propranolol levels), cimetidine (increases levels), rifampicin (reduces levels)