Examples

Thiazide diuretics

Loop diuretics

Loop diuretics are prescribed for people who also have heart failure, kidney problems, or swelling in their legs (edema), but they are rarely prescribed for people who have high blood pressure alone. Loop diuretics quickly increase urine output for a few hours.

Potassium-sparing diuretics

Potassium-sparing diuretics, unlike most other diuretics, do not cause potassium levels to drop. Rather, they may lead to high potassium levels.

Other

How It Works

Diuretics cause the kidneys to remove more sodium and water from the body which helps to relax the blood vessel walls, thereby lowering blood pressure.

Diuretics often are combined with other high blood pressure medicines. Some of the brand names listed here are a combination of a diuretic and another medicine. Using both a diuretic and another medicine often works well because diuretics can enhance the effect of the other medicines and sometimes prevent the fluid retention that can occur.

Why It Is Used

Diuretics are recommended as the first line of treatment for high blood pressure.¹ They are usually recommended as one of at least two medicines to control high blood pressure.

Diuretics are especially beneficial in African Americans, older adults, people who are overweight, and people who have heart failure.

Because diuretics may raise cholesterol, make diabetes worse, cause gout, and make some types of heart disease worse, they need to be used carefully.

How Well It Works

Diuretics reduce the risk of heart disease, heart attack, and stroke by reducing blood pressure.

Loop diuretics don't work as well as thiazide medicines in people who have kidneys that function well.²

Side Effects

Side effects of diuretics include:

• Increased thirst.
• Increased urination for a few days after beginning the medicine (thiazide diuretics).
• Reduced levels of potassium, magnesium, and sodium in the blood. Very low levels of potassium can lead to serious irregular heartbeats (arrhythmias).
• Increased levels of uric acid (which may lead to gout), calcium, blood sugar (which may complicate control of diabetes), and cholesterol.
• Weakness.
• Erection problems (impotence).
• Excess fluid loss from the body (dehydration) and fainting at higher doses, especially in older adults.
• Dry mouth.
• Tooth decay (dental caries).
• Interaction with other medicines, such as nonsteroidal anti-inflammatory drugs (NSAIDs), certain cholesterol-lowering drugs (such as cholestyramine), and lithium, a medicine used to treat certain mental illnesses.

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

Potassium pills may need to be taken with some diuretics. A diet high in potassium also may be needed. Potassium is found in citrus fruits, bananas, tomatoes, and other foods. See your doctor before starting potassium supplements or making changes in your diet.

Most diuretics contain sulfa and should not be taken if you are allergic to it.

These drugs are often inexpensive, although a person may need regular blood tests while taking them, which can increase the cost of using them.

It is important to take high blood pressure medicines daily as prescribed. Because high blood pressure often has no symptoms, it is easy to forget to take the medicine.

If your high blood pressure medicine causes erection problems, you may want to talk to your doctor about erection-enhancing medicines such as sildenafil (Viagra).

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