Examples

Thiazide diuretics may be used for mild fluid buildup caused by mild to moderate heart failure.

Loop diuretics are generally used in people with more severe heart failure.

Potassium-sparing diuretics are sometimes taken with the above diuretics. For more information, see aldosterone receptor antagonists in the Medications section of the Heart Failure topic.

Various combinations of diuretics or diuretics and other medications (such as angiotensin-converting enzyme [ACE] inhibitors) are available.

How It Works

Diuretics stimulate the kidneys to remove more water and salt (sodium) from the body. Diuretics may also slightly dilate or widen blood vessels.

• Dosage often starts low and is increased as needed to reduce fluid buildup and prevent side effects.
• Diuretics can be taken 2 to 3 times per week, every other day, once a day, or several times daily. They are most often taken by mouth, but some can be injected into a vein if you are in the hospital.
• Some diuretics need to be taken with potassium supplements, a high-potassium diet (including citrus fruits, bananas, tomatoes), or ACE inhibitors to prevent the loss of too much potassium. If your potassium levels are too low, you may need a potassium-sparing diuretic.

Why It Is Used

These medicines are used if you have problems with the left ventricle's ability to pump along with symptoms of fluid buildup (such as difficulty breathing or swelling in your legs and ankles). Diuretics are often used with ACE inhibitors and may be combined with other medicines.

Another type of diuretic called spironolactone (Aldactone) may be an option if you are already taking other medicines for severe heart failure (such as ACE inhibitors, diuretics, digoxin, and beta-blockers) caused by left ventricular systolic dysfunction.¹ For more information, see aldosterone receptor antagonists in the Medications section of the Heart Failure topic.

How Well It Works

Diuretics help rid the body of extra fluid and sodium. They increase urination, decrease swelling in the legs, decrease breathlessness, and lower blood pressure. They also reduce the risk of complications caused by high blood pressure.

Side Effects

Diuretics are generally safe. It may take some time to determine the correct dose and the best time of day to take the drug, depending on your age, body size, kidney function, amount of fluid buildup, and dietary salt (sodium) intake.

• You will most likely urinate more often while taking a diuretic. Timing of the dosage can often be adjusted so that the increased urination doesn't occur at inconvenient times.
• The loss of fluid also leads to increased thirst. It is important to talk to your doctor about how much fluid intake is safe when taking a diuretic to avoid counteracting the effects of the drug.
• High doses of these drugs can cause dehydration or low blood pressure (hypotension). Older adults may be more prone to heat exhaustion if they are taking one or more diuretics.
• Diuretics can cause potassium loss, which may lead to an abnormal heartbeat (arrhythmia). ACE inhibitors raise potassium levels, so potassium loss may not develop if you are taking both types of medicine.

You may need a potassium supplement or a potassium-sparing diuretic when you are taking certain diuretics. The amount of potassium consumed in the diet may be enough in some cases, but people often need supplements or medicine changes to maintain appropriate potassium levels.

These drugs can cause changes in sugar and uric acid (a waste product of metabolism that causes gout). This is important for people who are at risk for diabetes, atherosclerosis, or gout.

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

What To Think About

If you take diuretics, your doctor may want you to weigh yourself every day to monitor water loss and to determine whether your medication should be adjusted.

You will need frequent blood tests to check potassium levels while you are taking a diuretic.

If the diuretics flush too much fluid and salt from your body, you may have kidney problems.

Diuretics can increase:

• The risk of dehydration.
• The risk of heat exhaustion.
• Blood sugar (a concern for people with diabetes).
• The level of uric acid in the blood, which increases the risk of gout.

Symptoms of low potassium may include muscle cramps and an irregular heartbeat. However, regular monitoring of your potassium levels will ensure that your doctor detects and corrects a low potassium level before you develop symptoms.

Diuretics may interact with nonsteroidal anti-inflammatory drugs (NSAIDs). Talk with your doctor before taking any other medicines.

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Citations

1. Heart Failure Society of America (2006). HFSA 2006 comprehensive heart failure practice guidelines: Executive summary. Journal of Cardiac Failure, 12(1): 10–38. Also available online: http://www.abouthf.org/guidelines.htm.