The combination of metoprolol with amlodipine, enalapril or furosemide is effective in lowering blood pressure. 1. Amlodipine: Amlodipine and other diphenhydramine antihypertensive drugs are mainly used to lower blood pressure by dilating small arteries and lowering peripheral resistance, and have synergistic antihypertensive effects when used in combination with metoprolol. Common adverse reactions include swelling of the lower limbs, headache, dizziness, etc. When applied for a long time, gingival hyperplasia, toothache, etc. After stopping the drug, the adverse reactions gradually diminish until they disappear. 2. Enalapril: is a kind of antihypertensive drug, mainly through the action of renin – angiotensin – aldosterone system, so as to produce the efficacy of lowering blood pressure. Its cardiovascular and renal protective effects can be enhanced when used in combination with metoprolol. A common adverse reaction is cough, usually dry cough. If cough symptoms occur and cannot be tolerated, it is recommended to switch to other antihypertensive drugs. 3. Furosemide: Furosemide is a diuretic, mainly used in the treatment of edematous diseases, in the application of antihypertensive can activate the sympathetic nerves, which can produce adverse effects on antihypertensive, and metoprolol can inhibit the excessive activation of sympathetic nerves, so that the two can be used in combination to counteract this unfavorable factor. Some patients have experienced allergic reactions such as skin rashes while taking furosemide, which resolved on their own after discontinuing the drug. The use of either one antihypertensive drug alone or in combination should be done under the supervision of a physician.