Verapamil, diltiazem, amiodarone, digoxin (risk of slow heart rate/heart block), clonidine (rebound hypertension on withdrawal), other antihypertensives/diuretics (additive BP lowering), insulin and antidiabetics (masks hypoglycemia), NSAIDs (may reduce BP-lowering effect), antidepressants like fluoxetine/paroxetine and other CYP2D6 inhibitors (increase metoprolol levels), adrenaline/other sympathomimetics (reduced effect or BP changes)