If your blood pressure is consistently above 140/90 mm Hg, you probably should be taking medication to lower it. If you have diabetes or kidney disease, your doctor will likely prescribe medication when your blood pressure is above 130/80 mm Hg, because elevated blood pressure is particularly dangerous in people with these illnesses.
The five most frequently prescribed medications for lowering blood pressure are diuretics, beta-blockers, ACE inhibitors, angiotensin II receptor blockers (ARBs), and calcium channel blockers. Most individuals require at least two medications to get their blood pressure under control, and guidelines recommend that one of these medications be a diuretic. However, the exact combination of drugs your physician prescribes will depend on your response to each as well as any other health problems you have or are at risk for developing.
These drugs, also called water pills, reduce blood pressure by increasing sodium excretion in the urine. This effect promotes water loss and decreases blood volume, which lowers blood pressure. Diuretics also increase blood flow by widening small blood vessels.
Thiazide diuretics, such as chlorthalidone and hydrochlorothiazide (Microzide), are the most commonly used diuretics. These medications are inexpensive, need to be taken only once per day, and are often the first drug tried in individuals with high blood pressure. In addition to their blood pressure-lowering benefits, these medications reduce the risk of heart attacks, heart failure, and strokes.
The potential side effects of thiazide diuretics include weakness, fatigue, erectile dysfunction, increased levels of blood glucose, uric acid, and triglycerides, reduced HDL cholesterol, and excessive potassium loss in the urine. To prevent potassium loss, which can cause cramps in the legs, your physician may recommend combining a thiazide diuretic with a potassium-sparing diuretic such as triamterene (Dyrenium). Your doctor may also advise taking potassium supplements or adding an ACE inhibitor or ARB to your drug regimen.
These medications, which interfere with the actions of the hormone adrenaline, lower blood pressure levels by slowing the heart rate and decreasing the amount of blood pumped by the heart. Because beta-blockers can also help alleviate symptoms of angina (chest pain), treat heart failure, and reduce the risk of death and future heart attacks in individuals who have had a heart attack, these medications are often prescribed to lower blood pressure levels in people with coronary heart disease. Commonly prescribed beta-blockers include atenolol (Tenormin), carvedilol (Coreg), metoprolol (Lopressor, Toprol XL), and propranolol (Inderal LA, Innopran XL).
The possible adverse effects of beta-blockers include fatigue, depression, erectile dysfunction, a mild rise in blood glucose and triglyceride levels, a slight fall in HDL cholesterol levels, and wheezing in people with asthma. If you are taking medication for diabetes, beta-blockers may mask the warning symptoms of low blood glucose (hypoglycemia) by interfering with the actions of adrenaline.
ACE inhibitors —like quinapril (Accupril), lisinopril (Prinivil, Zestril), and ramipril (Altace) —lower blood pressure levels by blocking the formation of an enzyme that produces angiotensin II. Angiotensin II constricts blood vessels and stimulates the adrenal glands to release a hormone called aldosterone that promotes sodium retention. ACE inhibitors reduce levels of angiotensin II, thus dilating blood vessels and allowing blood to flow through these vessels more easily. ACE inhibitors are also effective in preventing heart attacks and may reduce the risk of diabetes, kidney disease, and stroke.
ACE inhibitors have fewer side effects than diuretics or betablockers. A dry cough is the most common one. If you develop a cough, ask your physician if an ARB can be prescribed instead. Uncommon side effects include an increase in blood potassium levels and impaired kidney function. ACE inhibitors should not be taken by women who are pregnant or planning a pregnancy.
Angiotensin II receptor blockers (ARBs)
ARBs —for example, irbesartan (Avapro), losartan (Cozaar), and valsartan (Diovan) —work by interfering with the action of angiotensin II, preventing its negative effects on the heart and blood vessels. These drugs not only lower blood pressure but also protect the heart. For example, one study found that ARBs were helpful in the treatment of heart failure. They can also help prevent kidney disease in people with diabetes and may help prevent diabetes. ARBs also protect against strokes, particularly in people with hypertension and a thickening of the heart muscle called left ventricular hypertrophy.
Side effects are uncommon but include headache and stomach upset. If you are pregnant or planning a pregnancy, you should not take an ARB.
Calcium Channel Blockers
Calcium channel blockers lower blood pressure by preventing calcium from moving into the heart and blood vessels. This causes the coronary arteries to dilate and decreases the amount of blood pumped by the heart. Calcium channel blockers help alleviate symptoms of angina and reduce the risk of strokes and kidney disease. Amlodipine (Norvasc) is a commonly prescribed calcium channel blocker.
Long-acting calcium channel blockers are safer and more effective than the short-acting formulations. Flushing and swelling of the legs are occasional side effects.