(1) Thiazide diuretics
Thiazide diuretics help lower blood pressure by assisting the body in getting rid of excess sodium and water, thus decreasing blood volume. Because blood pressure is related to the amount of blood that the heart has to pump with each beat, decreasing blood volume can help lower blood pressure.
- Examples: Thiazide diuretics include hydrochlorothiazide (Microzide, HydroDiuril) and indapamine (Lozol), and potassium-sparing diuretics include spironolactone (Aldactone) and eplerenone (Inspra)
- Often prescribed for: People with salt-sensitive hypertension
- Not usually prescribed for: People with diabetes or allergies to sulfa drugs
- Potential interactions: Many thiazide diuretics used to treat high blood pressure can deplete the body of potassium, magnesium, zinc, and folic acid. Potassium-sparing diuretics may be used to help counter potassium loss from thiazide diuretics, but these can cause dangerously high blood potassium levels.
- Potential side effects: Thiazide diuretics may cause weakness, thirst, fatigue, potassium depletion, gout, frequent urination, muscle cramps, diarrhea or constipation, impotence, sensitivity to sunlight, increased blood sugar, allergy, and confusion. Side effects of many potassium-sparing diuretics are related to their effects on several hormones and include high blood potassium levels, male breast enlargement, erectile dysfunction, and menstrual irregularities in women. Unlike other potassium-sparing diuretics, eplerenone affects only the hormone aldosterone, and its side effects include headaches, dizziness, nausea, stomach pain, flu-like symptoms, and enlarged or sore breasts in males.
- Bottom line: The Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure recommends thiazide diuretics as the first line of therapy in the treatment of hypertension. If blood pressure cannot be adequately controlled with thiazide diuretics alone, your doctor may add one or more drugs from a different class.
(2) Angiotensin-converting-enzyme (ACE) inhibitors
Angiotensin II is a hormone that causes the kidneys to retain water and sodium and constricts the blood vessels. ACE inhibitors prevent the conversion of angiotensin I to angiotensin II in the blood, lowering blood pressure.
- Examples: captopril (Capoten), enalapril (Vasotec), lisinopril (Zestril), and quinapril (Acupril)
- Often prescribed for: People with people who have had a heart attack and those with underlying kidney dysfunction.
- Not usually prescribed for: People with kidney artery narrowing and pregnant women.
- Potential side effects: ACE inhibitors are generally well tolerated, but should not be used by pregnant women due to the risk of birth defects, or by people with severe narrowing of the kidney arteries (bilateral renal artery stenosis). ACE inhibitors may cause cough, low blood pressure, high blood potassium levels, drowsiness, weakness, headache, edema, and abnormal or loss of taste.
- Bottom line: ACE inhibitors cause fewer side effects than many other blood pressure-lowering medications. They improve survival after heart attacks and prevent kidney damage in people with high blood pressure and diabetes. Not everyone responds the same way to ACE inhibitors and more than one medication may be needed to achieve blood pressure control.
(3) Calcium-channel blockers
These work by decreasing the influx of calcium into the cells of the heart and blood vessel walls, limiting the force of heart contractions and helping relax blood vessels. Both of these actions help to decrease blood pressure.
- Examples: amlodipine (Norvasc), Diltiazem (Cardizem), nifedipine (Procardia XL), and verapamil (Calan)
- Often prescribed for: People who have had a heart attack and cannot tolerate beta-blockers.
- Not usually prescribed for: People with heart failure or for reducing subsequent heart attacks or preventing kidney failure.
- Potential side effects: Calcium-channel blockers may cause headache, dizziness, fluid retention (edema), constipation, rash, nausea, low blood pressure, drowsiness, dizziness, and sexual dysfunction. Diltiazem and verapamil may worsen heart failure.
- Bottom line: Calcium-channel blockers work as well as ACE inhibitors for bringing down high blood pressure, but they don’t seem to protect against kidney failure caused by high blood pressure. Unlike beta-blockers, calcium-channel blockers do not appear to lower the risk of subsequent heart attacks or death from heart disease when taken after a heart attack.
Beta-blockers block the hormones epinephrine and norepinephrine from binding to beta receptors on cells. These hormones have different effects in the body, depending on the type of beta receptor that they bind to. Beta-blocker drugs predominantly work on beta receptors in the heart, blood vessels, and lungs. Here, they slow heart rate and dilate blood vessels to decrease blood pressure, and they may constrict the airways. Some beta-blockers act primarily on the heart, and do not affect the blood vessels or airways. These are called selective beta-blockers.
- Examples: Selective beta-blockers include atenolol (Tenormin) and metoprolol (Lopressor, Toprol XL); non-selective beta-blockers include propranolol (Inderal) and timolol (Blocadren)
- Often prescribed for: People who have had a heart attack
- Not usually prescribed for: People with underlying heart failure or lung disease
- Potential side effects: Beta-blockers may cause diarrhea, stomach cramps, nausea, vomiting, headache, depression, confusion, insomnia, decreased HDL cholesterol, dizziness, high or low blood sugar levels and masking of low blood sugar in diabetics, sexual dysfunction, and worsening of heart failure and peripheral vascular disease. Abrupt withdrawal may cause angina, heart attack, or sudden death. Both types of beta-blockers can cause worsening of lung function in people with asthma or other lung diseases. Non-selective beta-blockers are potentially more dangerous for people with underlying lung disease.
- Bottom line: Unlike most other antihypertensive medications, beta-blockers taken during and after a heart attack help prevent subsequent heart attacks and reduce the risk death from heart disease.
(5) Angiotensin II-receptor blockers
ARBs are similar to ACE inhibitors in that they both act on the hormone angiotensin II. Whereas ACE inhibitors block the conversion of angiotensin I to angiotensin II, ARBs block the binding of angiotensin II to receptors on cells. When angiotensin II is blocked, the blood vessels relax, sodium and water are excreted from the kidneys, and blood pressure goes down.
- Examples: candesartan (Atacand), irbesartan (Avapro), olmesartan (Benicar), eprosartan (Teveten), and losartan (Cozaar).
- Often prescribed for: Preventing kidney damage in people with high blood pressure or diabetes, people with heart failure, and people who experience side effects from ACE inhibitors (especially cough).
- Not usually prescribed for: People with kidney artery narrowing and pregnant women.
- Potential side effects: ARBs are generally well tolerated. The most common side effects are muscle cramps, dizziness, abnormal taste sensation, high blood potassium levels, confusion, vomiting or diarrhea, and cough (less so than with ACE inhibitors).
- Bottom line: ARBs come with fewer side effects than most of the other antihypertensive drugs.
What is high blood pressure?
A blood pressure reading is made up of two numbers: the upper is called the systolic pressure and the lower is the diastolic pressure. Both are important in determining if a person has high blood pressure. Here’s a breakdown of blood pressure categories:
- Normal: Less than 120/80
- Prehypertension: 120 to 139/80 to 89
- Stage I hypertension: 140 to 159/90 to 99
- Stage II hypertension: 160/100 or higher
If the systolic and diastolic readings fall into different categories, the reading in the higher category determines the blood pressure category. For example, if a person has a blood pressure of 135/92, they would be categorized as having stage I hypertension.
Who should take medication for high blood pressure?
If your blood pressure is high, your doctor can help you decide when medication is needed. For mild hypertension, medications often aren’t necessary. A review of studies that looked at the use of blood pressure–lowering medications in people with mild hypertension found no less risk of heart attack, stroke, or death. People with prehypertension and stage I hypertension may benefit most from eating more vegetables, fruits, nuts, fish, and legumes, quitting smoking, and taking up a regular exercise program.
“My doctor diagnosed me with mild hypertension about two years ago. She wanted to put me on medication, but I really wanted to see if I could get my blood pressure down naturally,” says Joya Maxwell, 69, of Rhode Island. “I started eating more vegetables, making green smoothies for myself every morning, and I took up walking again. The next time I saw my doctor, my blood pressure was in a normal range. I’m just happy not to have to take a medication if I don’t need to.”
It may take a trial of different medications to find the ideal drug or combination of drugs that will help lower blood pressure in a person with hypertension. Some common drug combinations are now offered in a single pill to make it easier to stick to treatment.