Cardiovascular Advisor

What is a diuretic?

A diuretic is a medicine taken to help your body lose water and salt through your urine. There are many different kinds of diuretics. Examples include furosemide (Lasix), spironolactone (Aldactone), and hydrochlorothiazide (HCTZ). Diuretics are sometimes called water pills.

When are diuretics used?

Diuretics are most often used when too much water builds up in the body. This happens when a diseased heart cannot pump well and water collects in body tissues, causing a condition called heart failure. This type of medicine is also used to treat:

• high blood pressure
• glaucoma, a condition in which there is increased fluid pressure in the eye, which can cause blindness
• edema (swelling in the ankles and feet).

Diuretics work better if you lower the salt (sodium) in your diet. Ask your healthcare provider or dietitian how to do this.

How do they work?

Diuretics work on the kidneys to increase the amount of sodium and water taken out of your body. Less fluid in the blood vessels helps to lower the pressure on the walls of your arteries. The different kinds of diuretics work in slightly different ways. Your healthcare provider will choose the type that is best for you.

Diuretics can lower the levels of both sodium and potassium in your body. Potassium is a mineral that helps your heart rhythm stay regular, among other things. Diuretics that make you lose potassium are called potassium-wasting diuretics. Others cause your body to hold onto potassium and are called potassium-sparing diuretics. Ask your healthcare provider which type you are taking. You will need to have regular blood tests to check your potassium levels.

What should I watch out for while taking this medicine?

If you are taking a diuretic that makes you lose potassium, the level of potassium in your blood can get too low. This can make you feel weak and cause your heart to beat irregularly. You may not be able to feel the irregular heartbeats, but it may be dangerous. Your provider may tell you to eat foods that have more potassium. Potassium is found in leafy vegetables, fruit and vegetable juices, and bananas. Dried fruits like raisins have high amounts of potassium. Your healthcare provider may give you potassium in pill form.

If you are taking a diuretic that makes you hold on to potassium, the level of potassium in your blood can get too high. This may cause slow or irregular heartbeats. Some other types of medicines, such as ACE inhibitors, can also make your body hold onto potassium. Taking drugs like these with diuretics can make it more likely that you will have problems with high levels of potassium. Also, if you have diabetes or kidney disease, you are more likely to have high potassium levels when taking potassium-sparing diuretics.

Because diuretics lower blood pressure, you may become lightheaded or even faint when you stand. This is more likely if you are also taking other medicines for high blood pressure. If you have these symptoms, tell your healthcare provider right away.

Diuretics may raise the level of uric acid in your blood and increase your risk of gout. If you are diabetic, diuretics may increase your blood sugar. You may need to check your blood sugar more often when you first start taking a diuretic.

Report these side effects to your healthcare provider right away:

• palpitations (irregular or forceful heartbeats)
• unusual weakness
• nausea and vomiting
• rash or itching.

Diuretics are very useful drugs and are very safe when used as prescribed. Talk with your healthcare provider or pharmacist if you have any questions.