Clinical studies have found that monotherapy of hypertension is satisfactory in only 50-60% of patients, 20-30% of patients need a combination of two drugs, and 10-20% of patients need a combination of three or even three or more drugs. Practice has shown that the following methods are suitable for the combination of drugs: 1, diuretics and β-blockers combined: β-blockers (such as propranolol, betalactam, etc.) inhibit myocardial contractility, so that cardiac output decreases, which can weaken the activation of the renin system by diuretics (such as dihydrochlorothiazide, indapamide, etc.) and strengthen the antihypertensive effect of diuretics; can prevent or reduce diuretic-induced hypokalemia by It can prevent or reduce the serious ventricular arrhythmias induced by diuretic hypokalemia. The combination of the two can prevent sudden death and reduce the occurrence of reinfarction after myocardial infarction, while the antihypertensive effect is synergistic. 2. Combination of diuretics and α-blockers: α-blockers (such as prazosin) can block post-synaptic α1 receptors and dilate blood vessels, thus achieving antihypertensive effect, but at the same time, it can lead to water and sodium retention, so combining with diuretics can improve the antihypertensive effect and reduce side effects. The effect of diuretics on raising blood cholesterol, triglycerides and LDL can be reversed. However, alpha-blockers are prone to first-dose effects, i.e., postural hypotension. Since diuretics can reduce blood volume, the first dose effect is more likely to occur when combined with diuretics, so it is better not to combine with diuretics when starting to use α-blockers. 3, diuretics and ACEI (angiotensin converting enzyme inhibitor) combination: ACEI (such as captopril, enalapril, etc.) unlike other vasodilators and some adrenaline blockers will cause water and sodium retention, but the combination with diuretics can significantly enhance its antihypertensive effect, especially for high renin hypertension, the antihypertensive effect is more significant, and can reduce the thiazide diuretics caused by hypokalemia However, it should not be used in combination with potassium-protective diuretics (aminoglutethimide, aminoglutethimide) because it can aggravate the hyperkalemia caused by potassium-protective diuretics. 4, β-blockers and dihydropyridine calcium antagonists together: dihydropyridine calcium antagonists including nifedipine, nidulodipine, felodipine and amlodipine, etc., these drugs can cause reflex tachycardia, increased myocardial contractility and increased cardiac output while lowering blood pressure, β-blockers block the β receptors, α receptor excitability is relatively high, and peripheral resistance is mildly increased, the two drugs together to lower blood pressure The combination of the two drugs has a combined antihypertensive effect, and the side effects can be reduced to the mildest degree, which is the most commonly used prescription for antihypertensive combination. It is worth noting that non-dihydropyridine calcium antagonists such as verapamil should not be used in combination with β-blockers, especially when injected intravenously at the same time, which can cause severe heart block or even cardiac arrest and significantly inhibit cardiac function, so it is contraindicated, and oral combination is also undesirable. Non-dihydropyridine calcium antagonists (such as diltiazem, verapamil) are contraindicated in patients with heart block and heart failure, and should not be used in combination with beta-blockers. 5, calcium antagonists and ACEI combination: ACEI inhibits the release of renin, calcium antagonists can increase the plasma renin levels, the combination of hypertension in the elderly with low renin levels is beneficial. The combination of low-dose ACEI and calcium antagonist reduces proteinuria and ankle edema more than either one alone. Angiotensin II receptor antagonists are currently commonly used drugs such as valsartan (Dextran), which have fewer side effects than angiotensin-converting enzyme inhibitors and can be used instead of the latter, but they are more expensive and should be used reasonably according to the patient’s economic conditions.