Diuretics (Water Pills) for High Blood Pressure

Commonly known as "water pills," these drugs help your kidneys get rid of extra water and salt from your body through your pee. Because you have less total fluid in your blood vessels, like a garden hose that's not turned on all the way, the pressure inside will be lower. This also makes it easier for your heart to pump.

They're usually the first type of medication that your doctor will try to control your blood pressure.

Drug Names

You'll often start with a thiazide diuretic:

Others your doctor may prescribe are:

Different diuretics can be taken together, and you can take them with other medications, sometimes in the same pill.

While You're Taking Diuretics

Let your doctor know what medications (prescription and over-the-counter), supplements, and herbal remedies you use. Also, tell her about other medical problems you have.

She may want to regularly check your blood pressure as well as test your blood and pee for levels of specific minerals and to see how well your kidneys are working. She'll probably tell you to follow a low-sodium diet and limit how much salt you eat.

Because some diuretics also pull potassium out of your body, you might need to eat more foods like bananas, sweet potatoes, spinach, and lentils, or take a potassium supplement. On the other hand, if you're taking a "potassium-sparing" diuretic, such as amiloride (Midamar), spironolactone (Aldactone), or triamterene (Dyrenium), she may want you to avoid potassium-rich foods, salt substitutes, low-sodium milk, and other sources of potassium.

If you only need one dose a day, you might want to take your diuretic in the morning so you can sleep through the night instead of getting up to go to the bathroom.

Avoid alcohol and medicines to help you sleep. They may make side effects worse.

Side Effects

The water that comes out of your body has to go somewhere, so you can expect to be peeing more and more often for several hours after a dose.

Continued

You also run the risk of getting dehydrated, and simply drinking more fluids may not be enough. Call your doctor if you're very thirsty or have a very dry mouth, your pee is a deep yellow, you aren't peeing much or get constipated, or you have a bad headache.

You may feel dizzy or lightheaded, especially when you stand up, if your blood pressure has dropped too low, or you're getting dehydrated.

Your blood chemistry can get thrown off. You could have too little or too much sodium or potassium in your system. This can make you tired or weak or give you muscle cramps or a headache. It's rare, but your heart may speed up (over 100 beats a minute) or you might start throwing up because of a dangerously low potassium level.

Diuretics may make it harder for you to control your blood sugar, which can lead to diabetes if you don't already have it. You might be more likely to get gout.

Taking combination pills or multiple medicines could boost these side effects. To help lower those odds, ask your doctor when during the day you should take each medication.

Who Shouldn't Take Them?

Some diuretics are sulfa drugs, so they could cause a reaction if you're allergic.

Older people tend to have more side effects such as fainting and dizziness from dehydration. You'll need to work closely with your doctor.

Diuretics aren't recommended for women who are pregnant or breastfeeding. We don't know how these drugs affect an unborn baby. And many pass into breast milk, which can make the baby dehydrated.

Kids can safely take them, but they need smaller doses. The side effects are similar to adults. But potassium-sparing diuretics can cause low levels of calcium, which could hurt bone development.

WebMD Medical Reference Reviewed by James Beckerman, MD, FACC on May 02, 2017

Sources

American Heart Association: "Types of Blood Pressure Medications."

Blood Pressure UK: "Diuretics - blood pressure medication."

Mayo Clinic: "High blood pressure (hypertension): Diuretics."

European Heart Journal: "Adverse reactions to diuretics."

Consumer Reports: "What to Know About Diuretics for High Blood Pressure."

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