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Everything you need to know about water pills

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Uses and typesKidney safetyOnset of actionBloatingWeight lossSummary
Diuretics, also called water pills, help your body get rid of excess water and salt. Healthcare professionals may prescribe them for conditions like high blood pressure or fluid buildup (edema).
Medically reviewed by Alisha D. Sellers, BS Pharmacy, PharmD
Updated on

In the United States, you need a prescription to purchase most diuretics. Some over-the-counter (OTC) products also claim to lower water retention, though they may not be as effective for managing long-term (chronic) conditions. 

What do water pills do?

Yellow water pills next to a glass of water on a yellow background.
Marc Tran/Stocksy United

Several types of diuretics exist, and although their main function is to help your body remove excess fluid and sodium, each may have different action mechanisms. 

Thiazide diuretics

Thiazides work by blocking a channel in the kidneys called the sodium-chloride or Na-Cl channel. This prevents the reabsorption of up to 5% of sodium, making your body expel more salt and water. These diuretics may also cause a drop in potassium levels. 

The Food and Drug Administration (FDA) has approved thiazides for management of high blood pressure, as well as edema associated with:

  • chronic heart failure (CHF)
  • liver disease (hepatic cirrhosis)
  • corticosteroid use
  • estrogen therapy
  • kidney disease

Thiazide diuretics are available as pills. Options may include: 

Loop diuretics

Loop diuretics work by blocking a specific transporter in the kidneys to prevent the reabsorption of sodium, potassium, and chloride. In turn, this helps your body get rid of water and salt. 

Loop diuretics are FDA-approved to treat edema linked with:

  • CHF
  • liver cirrhosis
  • kidney disease

The FDA has also approved these medications for high blood pressure, though healthcare professionals may prefer thiazides for this purpose.

In addition, intravenous (IV) loop diuretics can help treat fluid overload after heart failure. 

Loop diuretic drugs are available in oral, injection, and IV forms and may include:

Potassium-sparing diuretics 

Potassium-sparing diuretics raise urine output without causing a loss of potassium and magnesium. Like thiazide and loop diuretics, they work by reducing the reabsorption of sodium in the kidneys to promote water excretion. 

These diuretics are suitable for people with high blood pressure who have lost too much magnesium or potassium. Some of these diuretics may also help treat conditions associated with too much androgen hormones, like primary aldosteronism or excessive body hair growth (hirsutism). 

Potassium-sparing diuretics may include:

Other types

Other types of diuretics may include:

  • carbonic anhydrase inhibitors
  • osmotic diuretics like mannitol (Osmitrol)
  • sodium-glucose cotransporter-2 (SGLT2) inhibitors like bexagliflozin (Brenzavvy)

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Are water pills bad for the kidneys?

Diuretics are generally safe to use under the guidance of a medical professional. These drugs are usually not toxic to the kidneys. 

However, you may need to avoid

  • potassium-sparing diuretics if you have advanced kidney failure or chronic kidney disease
  • mannitol if you have kidney disease
  • loop or thiazide diuretics if you also take nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen (Advil)

A healthcare professional will assess your health before prescribing diuretics to make sure they’re safe for you and your kidneys. Discuss OTC water pills with your healthcare professional to learn whether they’re suitable for your needs.

Do you need to drink more water when taking diuretics?

Taking diuretics may cause increased fluid loss, potentially causing dehydration. 

Specifically, diuretics may cause a type of dehydration called hypotonic dehydration, characterized by increased loss of salt. 

So it’s important that you maintain proper hydration by drinking enough water throughout the day.

A good sign of whether you need to drink more water is to monitor the color of your urine, aiming for pale yellow.

Consulting with a healthcare professional before taking OTC diuretics or engaging in physical exertion if you take prescription diuretics is highly recommended.

How long does it take for diuretics to work?

Most diuretics start working within 1 hour, sometimes sooner. The duration of action also varies with the effects of some medications lasting longer than others. 

Always follow the directions of a healthcare professional when it comes to dosage and timing.

Can you use water pills for everyday bloating and puffiness?

Diuretics are prescription medications. They’re FDA-approved for specific medical conditions like high blood pressure and edema. They’re not suitable for everyday bloating and puffiness not associated with the medical conditions the diuretics aim to treat. 

OTC water pills may be marketed as solutions for bloating and puffiness. However, if you live with a chronic condition (or you don’t know if you may), it’s better to talk with a healthcare professional before you rely on these pills.

Finding the root cause of persistent bloating and puffiness is the first step toward managing these symptoms.

Bloating may be linked with a wide range of conditions, such as:

Do water pills help you lose weight?

While diuretics can cause temporary weight loss as your body gets rid of excess water, this is not a sustainable or suitable approach to weight management. 

Using water pills for weight loss poses risks, including dehydration and electrolyte imbalances.

A healthcare professional can guide you toward safe and sustainable methods for weight loss. These methods might include lifestyle changes and FDA-approved prescription weight loss medications

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Diuretics are prescription medications that help your body remove excess water and salt. They may help treat high blood pressure and edema. They’re not suitable for weight management or to manage persistent bloating. 

OTC water pills may be marketed as medications with the same purpose, but they’re not considered safe or effective.

A healthcare professional may advise you on the use of OTC water pills or prescription diuretics. 

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