What Is a Diuretic? Uses, Warnings, Side Effects, and More
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What Is a Diuretic? Uses, Warnings, Side Effects, and More

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Updated on November 29, 2022
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Diuretics are a class of medications commonly known as "water pills." There are several different classes of diuretics, each of which works differently in the kidneys to help rid the body of extra water and salt.

Most diuretics help your kidneys release more sodium into your urine, according to Mayo Clinic. The sodium helps remove water from your blood, decreasing the amount of fluid that flows through your veins and arteries, which in turn reduces blood pressure.

Each type of diuretic affects a different part of your kidneys, notes Mayo Clinic. Some medications combine more than one type of diuretic, or combine a diuretic with another blood pressure medication.

Uses

Diuretics are recommended as a first-line treatment for high blood pressure, per Mayo Clinic.

They are also commonly recommended for people who have the following conditions:

Types

There are three main types of diuretics, per Mayo Clinic. These include:

  • Thiazide diuretics, like chlorthalidone, chlorothiazide, hydrochlorothiazide, indapamide, and metolazone.
  • Loop diuretics, such as furosemide, bumetanide, ethacrynic acid, and torsemide.
  • Potassium-sparing diuretics, including amiloride, eplerenone, triamterene, and spironolactone.

Precautions and Warnings

You should not take any type of diuretic if you have severe dehydration, anuria (lack of urine production), or an electrolyte abnormality, per StatPearls.

Avoid taking any diuretic drug to which you have a known hypersensitivity.

If you have gout, do not take loop or thiazide diuretics.

Avoid taking loop diuretics if you have certain conditions, including hypokalemia (low potassium levels), severe hyponatremia (low sodium levels), hypotension (low blood pressure), oliguria (low urine output), or if you are expecting to have fluid depletion, such as during surgery.

Take loop diuretics instead of thiazides (except metolazone) if you have chronic kidney disease and extra urine production is required.

Do not take potassium-sparing diuretics if you have hyperkalemia (high potassium levels), advanced kidney failure, or chronic kidney disease. Certain potassium-sparing diuretics should also be avoided during pregnancy.

Ask your doctor about the best type of diuretic for you if you have severe chronic obstructive pulmonary disease.

If you’re being treated with diuretics, your doctor should carefully and regularly assess your urine output, electrolyte level, body weight, blood pressure and other vials, especially if you are elderly or if you have cardiovascular, liver, kidney, or metabolic disorders.

If you are taking loop diuretics, baseline auditory tests are recommended to avoid hearing or balance problems.

If you are using any diuretic and it does not increase your urine output, you should stop taking the medication, as it could be a sign of undiagnosed, underlying kidney disease.

Common Side Effects

According to Mayo Clinic, side effects of diuretics include:

  • Increased urination
  • Sodium loss
  • Hypokalemia (low potassium levels): Thiazide diuretics can cause hypokalemia, which can cause life-threatening problems with your heartbeat.
  • Hyperkalemia (too much potassium in your blood): Potassium-sparing diuretics can cause hyperkalemia.

Other possible side effects of diuretics include:

  • Dizziness
  • Headache
  • Dehydration or increased thirst
  • Muscle cramps
  • Joint disorders (gout)
  • Impotence
  • Digestive problems, upset stomach, or abdominal pain

According to an article published in StatPearls, rare side effects of diuretics include:

  • Impotence
  • Skin reactions
  • Anemia
  • Muscle cramps

Side effects are more likely with loop diuretics, notes StatPearls.

Drug Interactions

Nonsteroidal anti-inflammatory drugs (NSAIDs) can suppress kidney production when used simultaneously with loop or thiazide diuretics, which can lead to acute kidney failure.

Take care when using loop diuretics along with other drugs that can cause hearing or balance issues, such as aminoglycoside antibiotics.

Avoid taking diuretics that may induce hypokalemia in combination with digoxin (used for heart failure) or quinidine (used for arrhythmias).

Bendroflumethiazide, a thiazide diuretic, can cause calcium retention, so take care when using the drug along with calcium supplements or vitamin D.

Potassium-sparing diuretics should not be taken at the same time as another potassium-sparing diuretic to avoid the risk of hyperkalemia.

Common Questions & Answers

What does a diuretic do to the body?
Diuretics, or "water pills," help rid the body of extra water and salt (sodium). Most diuretics help your kidneys release more sodium into your urine, which helps remove water from your blood, decreasing the amount of fluid that flows through your veins and arteries.

Diuretics are typically used as a first-line treatment for high blood pressure. They are also commonly recommended for people with conditions including heart failure, liver failure, tissue swelling (edema), and kidney disorders, such as kidney stones.

There are three main types of diuretics. These include: thiazide diuretics, like chlorthalidone, chlorothiazide, hydrochlorothiazide, indapamide, and metolazone; loop diuretics, such as furosemide, bumetanide, ethacrynic acid, and torsemide; and potassium-sparing diuretics, including amiloride, eplerenone, triamterene, and spironolactone.

The three most common thiazide diuretics are hydrochlorothiazide (HCTZ), chlorthalidone, and indapamide. HCTZ and chlorthalidone are used to manage primary hypertension.

The Takeaway

Diuretics, commonly known as water pills, help remove excess water and salt from your body, lowering your blood pressure in the process. There are three main types of diuretics — thiazide, loop, and potassium-sparing — each affecting different parts of your kidneys. Talk to your doctor about the best type for you, especially if you have other health conditions.

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Michael Cutler, DO, PhD, is a cardiac electrophysiologist at Intermountain Heart Rhythm Specialists in Salt Lake City, Utah. His research interests include understanding the cellular and molecular mechanisms of cardiac arrhythmia, gene therapy for cardiac arrhythmias, neural control of the circulation in sleep apnea, role of exercise in health and disease, and improving the management of cardiac arrhythmias (i.e., atrial fibrillation).

He completed his BS and MS in exercise physiology and was a member of the track/cross country team at the University of Utah in Salt Lake City. Prior to attending medical school, Dr. Cutler was an adjunct clinical instructor in the College of Health at the University of Utah and also served on the Utah Governor’s Council on Health and Physical Fitness. He then attended the University of North Texas Health Science Center in Fort Worth for medical school and for his PhD in cardiovascular physiology.

After medical school, Cutler entered the highly selective ABIM Research Pathway physician-scientist training program at the MetroHealth Campus of Case Western Reserve University in Cleveland. During this time, he completed his clinical training in internal medicine, cardiology and clinical cardiac electrophysiology, served as chief cardiology fellow, and received the Kenneth M. Rosen Fellowship in cardiac pacing and electrophysiology from the Heart Rhythm Society. Following residency and fellowship, Cutler accepted a position as an assistant professor of medicine at the MetroHealth Campus of Case Western Reserve University until he joined his current partners at Intermountain Heart Rhythm Specialists.

Cutler's research has received meritorious recognition from the American Physiological Society, the American Heart Association, and the Heart Rhythm Society.

Cutler has been an author on publications in journals such as Circulation, Circulation Research, Proceedings of the National Academy of Science, and Nature. He is board certified in internal medicine, cardiovascular disease, and clinical cardiac electrophysiology through the American Board of Internal Medicine.

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Frieda Wiley, PharmD, is a bestselling author, award-winning freelance medical writer, and pharmaceutical consultant who has written for O, The Oprah Magazine, WebMD, AARP, Costco Connection, and the National Institutes of Health, as well as for a host of pharmaceutical companies, universities, and associations.

Her first book, Telecommuting Psychosis: From Surviving to Thriving While Working in Your Pajama Pants, became an Amazon bestseller in two categories and the No. 1 new release in educational research on Amazon.

Trained as a scientist, Dr. Wiley holds bachelor degrees in biochemistry and Spanish from the University of Texas and enjoyed a brief career as a chemist in the aerospace industry, working for a company that specialized in turbine jet engine overhaul and repair. She earned her doctorate in pharmacy from the University of the Incarnate Word Feik School of Pharmacy.

A passionate healthcare professional, she thrives on educating people about their bodies and medications in a way that is easy to understand. When Wiley is not writing, she enjoys traveling, jazz, great conversation — with or without a refreshing cup of herbal tea — and walking barefoot in the woods.

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EDITORIAL SOURCES
Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy. We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.
Additional Sources
  • Diuretics. Mayo Clinic. August 13, 2021.
  • Arumugham VB, Shahin MH. Therapeutic Uses of Diuretic Agents. StatPearls. June 5, 2022.