What Are Diuretics?

Medically reviewed by Jamin Brahmbhatt, MD

Diuretics are a type of medication that help you eliminate excess water and salt from your body. They are mainly comprised of five types, including thiazides, loop diuretics, potassium-sparring diuretics, carbonic anhydrase inhibitors, and osmotic diuretics.

Diuretics can be prescribed to treat several conditions, such as high blood pressure, heart failure, liver cirrhosis, kidney problems, and glaucoma. In most cases diuretics are taken orally, but in some serious cases they are taken intravenously (IV).

What Do Diuretics Do?

Diuretics assist your body in eliminating excess water and sodium (salt) from your kidneys. They work by blocking receptors in your kidney tubules (the tubes in your kidneys that help your body filter fluids) that absorb sodium, allowing your body to excrete the excess sodium in your urine. By doing this, they can help lower your blood pressure and reduce fluid retention caused by like hypertension (high blood pressure) and swelling. This helps manage heart and kidney problems by easing strain on your body. They usually start working within a few hours of taking them.

Diuretics most often help to treat high blood pressure. However, they can also treat:

• Cirrhosis: This is a condition where scar tissue replaces healthy tissue in your liver, causing a variety of complications

• Congestive heart failure: This is a condition that occurs when your heart cannot pump blood adequately.

• Kidney disorders: Your kidneys are responsible for filtering your blood, so if you have a condition affecting your kidney you can be prone to blood pressure issues.

• Edema: Edema is characterized by an excessive amount of fluid being trapped in different areas of your body, causing swelling.

• Glaucoma: This is a group of eye disorders that damages your optic nerve, which is the nerve that transmits what you see to your brain, causing vision loss.

Types of Diuretics

There are five different types of diuretics. Each type works differently to eliminate excess salts and water from your body. Your healthcare provider may recommend a specific type of diuretic depending on your condition and its severity.

Thiazides

Thiazides are an FDA-approved class of drugs that stop about 3-5% the sodium in your kidney tubules from being reabsorbed back into your body. By doing so, they promote natriuresis, which is the release of sodium, and diuresis, which is the release of excess water in the body through increased urine production.

Low-dose thiazides are the first-line treatment for high blood pressure. A 2018 meta-analysis found them to be more effective than first‐line beta‐blockers, another common class of medications used to treat high blood pressure.

Thiazides can also help in the management of hepatic cirrhosis, congestive heart failure, calcium-associated kidney stones, and diabetes insipidus (a rare form of diabetes).

Medications in this group include:

• Hygroton (chlorthalidone)

• Microzide, Hydrodiuril, Esidrix (hydrochlorothiazide)

• Lozol (indapamide)

• Zaroxolyn, Mykrox (metolazone)

Loop Diuretics

Loop diuretics work by keeping your body from reabsorbing sodium in the thick ascending limb of the loop of Henle (which is located inside your kidneys). They achieve this by blocking a protein found on the apical membrane of the loop of Henle, called the Na-K-2Cl (NKCC2) co-transporter, which is responsible for absorbing sodium, potassium, and chloride. This action leads your body to expel excess water and salt, aiding in the management of conditions such as hypertension and edema.

Loop diuretics are generally considered the most effective among all other diuretics since they keep your body from absorbing the largest amount of sodium.

By increasing water excretion, loop diuretics help to manage edema and its associated conditions such as liver cirrhosis, congestive heart failure, nephrotic syndrome, and high blood pressure.

Medications in this group include:

• Lasix (furosemide)

• Bumex (bumetanide)

• SOAANZ, Demandex (torsemide)

Potassium-Sparing Diuretics

Potassium-sparing diuretics work by removing excess sodium and water from your body. However, unlike some other types of diuretics, they won't cause you to loose potassium. This protects you from hypokalemia (potassium deficiency).

Potassium-sparing diuretics are not as effective as other diuretics in reducing high blood pressure. They may be recommended alongside thiazides or loop diuretics.

Medications in this group include:

• Aldactone (spironolactone)

• Midamar (amiloride hydrochloride)

• Dyrenium (triamterene)

• Inspra (eplerenone)

Carbonic Anhydrase Inhibitors

Carbonic anhydrase inhibitors are medications that block the action of an enzyme called carbonic anhydrase. This enzyme is involved in various body processes, and inhibiting it can have effects like reducing eye pressure or increasing urine production.

Carbonic acid inhibitors can help to treat glaucoma, acute mountain sickness, and edema due to congestive heart failure.

Medications in this group include:

• Diamox, Sequels (acetazolamide)

• Neptazane (methazolamide)

• Cosopt (dorzolamide)

Osmotic Diuretics

Osmotic diuretics remove extra water from your body without disrupting the balance of electrolytes. They achieve this by increasing the concentration of solutes (such as electrolytes) in the tubular fluid. This makes it harder for water to be reabsorbed. Mannitol is a commonly used osmotic diuretic that isn't absorbed well by the body, so it pulls water with it as it moves through.

How are Diuretics Given?

Most often, diuretics are taken in pill form by mouth. But in certain cases (such as heart failure) they may be administered through an IV in a hospital setting.

The type of diuretic you're prescribed varies depending on your condition, how it needs to be taken, and how much you need.

Potential Side Effects

You may experience one or more side effects following the intake of diuretics. These include:

• Headache

• Fatigue

• Weakness

• Dehydration

• Gastrointestinal disorders such as abdominal pain, diarrhea, constipation, and vomiting

• Low potassium levels

• Electrolyte imbalance

In a few cases, diuretics can lead to severe side effects such as:

• Anemia

• Skin reactions

• Impotence

• Low blood platelet count

Other Considerations

Diuretics are generally safe to take. However, some risks are associated with certain medical condition or other medications.

Certain Conditions

Inform your healthcare provider if you have any medical conditions before taking diuretics since they can worsen the condition. A few conditions that may worsen due to diuretics include:

• Gout

• Pregnancy

• Chronic kidney disease

• Pancreatitis

• Diabetes

• Menstrual irregularities

Drug Interactions

Certain drugs may interact with diuretics and can interfere with how well they work. These include:

• Lanoxin, Cardoxin (digoxin)

• Salicylates

• Aminoglycosides

• Cardioquin, Cin-Quin, Quinidex (quinidine)

• Other blood pressure-lowering drugs such as beta-blockers, angiotensin II receptor blockers (ARBs), and angiotensin-converting enzyme inhibitors (ACEIs)

When To Call Your Healthcare Provider

You may want to call your healthcare provider if you are experiencing any side effects due to taking a diuretic, including dizziness, weakness, and nausea, among others. This can help them understand your condition and prescribe a different medication, if needed.

If your diuretics are causing extreme dehydration, seek immediate medical attention. Severe symptoms of dehydration include confusion, fainting, not urinating, having an abnormally fast heart rate, and unusually fast breathing.

A Quick Review

Diuretics are drugs that help to remove extra water and sodium from your body. They are five different types, including thiazides, loop diuretics, carbonic anhydrase inhibitors, potassium-sparring diuretics, and osmotic diuretics. Each of them works differently and are prescribed based on your individual symptoms and conditions.

If you need a diuretic, your healthcare provider will recommend the type and dosage based on your specific circumstances. In some cases, diuretics can lead to side effects, interfere with certain medications, and worsen certain medical conditions.

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