What Water Pills Are Available? 6 Types of Diuretics, Including Over-the-Counter Options

Water pills, or diuretics, are some of the most commonly prescribed medications. In fact, in 2023, two different water pills were among the top 30 medications prescribed in the U.S. They can help treat various health conditions, such as high blood pressure and heart failure.

Water pills work in your kidneys to remove excess fluid and salt from your body. But each type of diuretic does this in a slightly different way. Most diuretics require a prescription. But there are a few over-the-counter (OTC) water pills.

So what types of diuretics are available? Here are six types of water pills and what they’re typically used for.

1. Thiazide and thiazide-like diuretics

Thiazide and thiazide-like diuretics are some of the most commonly used diuretics. They’re first-choice water pills for hypertension (high blood pressure). At higher doses, they can also help treat edema (swelling).

Examples of thiazide and thiazide-like diuretics include:

• Hydrochlorothiazide (Microzide)

• Chlorthalidone (Thalitone, Hemiclor)

• Indapamide

• Metolazone

Thiazide and thiazide-like diuretics work very similarly. But they differ in their chemical structures. Some studies suggest that thiazide-like diuretics may offer more heart protection. Others didn’t find this to be true. The American Heart Association doesn’t recommend one over the over since both provide significant benefits.

Thiazide and thiazide-like diuretics can cause dehydration and certain electrolyte imbalances. Notably, they can decrease levels of potassium, sodium, and magnesium. But they may raise levels of calcium. Your prescriber should have you go for blood tests from time to time to keep an eye on your electrolyte levels.

Good to know: Hydrochlorothiazide is commonly included in combination blood pressure medications to help boost their effects. If you see the letters “HCTZ” on your prescription label, it means hydrochlorothiazide is in the medication.

2. Loop diuretics

Loop diuretics are another common class of water pills. They typically get rid of more fluid than other available diuretics. They’re a preferred option for relieving edema, especially for people living with heart failure.

Example of loop diuretics include:

• Furosemide (Lasix)

• Torsemide (Demadex, Soaanz)

• Bumetanide (Bumex)

• Ethacrynic acid (Edecrin)

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Loop diuretics have a higher risk of dehydration than other diuretics. They’re also more likely to cause low potassium. But they have a lower risk of causing decreased sodium levels. Your prescriber should have you go for blood tests to monitor these electrolyte levels.

Most loop diuretics are sulfa drugs. So if you have a sulfa allergy, you may not be able to take them. One exception to this is ethacrynic acid, which isn’t sulfa based.

3. Potassium-sparing diuretics

Potassium-sparing diuretics are water pills that get rid of extra fluid. But they don’t cause your potassium levels to drop, unlike thiazide, thiazide-like, and loop diuretics.

There are two potassium-sparing diuretics available:

• Triamterene (Dyrenium)

• Amiloride (Midamor)

These water pills don’t lower blood pressure or relieve swelling much on their own. But they can be used to help raise potassium levels if you’re taking a different diuretic that lowers this electrolyte.

For instance, there are combination pills for each potassium-sparing diuretic that contain hydrochlorothiazide. Hydrochlorothiazide can be helpful for managing certain health conditions. And the triamterene or amiloride can help prevent low potassium from the hydrochlorothiazide.

Because these water pills help prevent potassium loss, they can cause potassium levels to get too high. As with other diuretics, you’ll need blood tests regularly to watch for electrolyte problems.

4. Mineralocorticoid receptor antagonists

Mineralocorticoid receptor antagonists (MRAs) are sometimes also called aldosterone antagonists. That’s because they work by blocking the hormone aldosterone. Aldosterone causes the body to hold on to more sodium (and fluid) but get rid of potassium. By blocking aldosterone, these water pills stop your body from holding on to extra fluid.

Examples of MRAs include:

• Spironolactone (Aldactone)

• Eplerenone (Inspra)

• Finerenone (Kerendia)

Finerenone is different from other MRAs. The chemical structures of spironolactone and eplerenone resemble certain steroid hormones in the body. But finerenone isn’t steroid based. This makes a difference when it comes to certain side effects. Notably, finerenone is less likely than other MRAs to cause a lower sex drive and gynecomastia (male breast growth).

MRAs are first-choice treatments for heart failure because they can help prevent stiffening of the heart muscle. But they don’t help reduce blood pressure or swelling as well as thiazide, thiazide-like, or loop diuretics. So MRAs aren’t typically prescribed on their own to manage blood pressure or edema.

Similar to potassium-sparing diuretics, MRAs can raise your potassium levels. So you’ll need to go for routine blood work to monitor for this.

5. Acetazolamide

Acetazolamide belongs to an older class of medications called carbonic anhydrase inhibitors. It’s not commonly prescribed. But acetazolamide is FDA approved to treat altitude sickness, glaucoma, epilepsy, and edema.

Similar to many loop diuretics, acetazolamide is a sulfa drug. So you shouldn’t take it if you’re allergic to these types of medication. And like many other water pills, acetazolamide can lower potassium levels. It can also raise your risk of developing kidney stones.

6. OTC water pills

There are several products OTC that cause a mild diuretic effect. Most of these use either caffeine or pamabrom as the key ingredient. Both of these water pills stimulate the kidneys to make urine faster than usual. They’re intended to help with bloating or slight swelling, usually because of menstrual cramps.

OTC water pills shouldn’t be used as a replacement for prescription diuretics. They also shouldn’t be combined with prescription diuretics unless a healthcare professional tells you to do so.

What happens when you stop taking water pills?

If you stop taking a water pill, your body won’t remove as much fluid. This could lead to sudden fluid retention. And if you’re taking water pills to help manage high blood pressure, your blood pressure will likely increase if you stop taking them.

This could be harmful, especially if you take diuretics to treat chronic conditions, such as heart failure. Your symptoms may worsen. And you may be at a higher risk for complications related to your condition.

Don’t stop taking your water pills unless your prescriber says this is OK. If you need to stop taking your diuretic, your healthcare team can help you do so safely.

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Written by:

Timothy Aungst, PharmD

Timothy Aungst, PharmD, has worked in pharmacy practice for a decade. He has served as an associate professor of pharmacy practice, a clinical pharmacist in outpatient cardiology management, and now in home healthcare.

Edited by:

Christina Aungst, PharmD

Christina Aungst, PharmD, is a pharmacy editor for GoodRx. She began writing for GoodRx Health in 2019, transitioning from freelance writer to editor in 2021.

Reviewed by:

Joshua Murdock, PharmD, BCBBS

Joshua Murdock, PharmD, BCBBS, is a licensed pharmacist in Arizona, Colorado, and Rhode Island. He has worked in the pharmacy industry for more than 10 years and currently serves as a pharmacy editor for GoodRx.

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