Diuretics, sometimes called water pills, treat a variety of conditions, such as high blood pressure, glaucoma and edema. Find out more about this class of medication. By Mayo Clinic Staff

Diuretics, sometimes called water pills, help rid your body of salt (sodium) and water. They work by making your kidneys put more sodium into your urine. The sodium, in turn, takes water with it from your blood. That decreases the amount of fluid flowing through your blood vessels, which reduces pressure on the walls of your arteries.

There are three types of diuretics: thiazide, loop and potassium-sparing. Each works by affecting a different part of your kidneys, and each may have different uses, side effects and precautions. Which diuretic is best for you depends on your health and the condition being treated.

Examples of thiazide diuretics include:

  • Chlorothiazide (Diuril)
  • Hydrochlorothiazide (Microzide)
  • Indapamide
  • Metolazone (Zaroxolyn)
  • Chlorthalidone

Examples of loop diuretics include:

  • Bumetanide
  • Ethacrynic acid (Edecrin)
  • Furosemide (Lasix)
  • Torsemide (Demadex)

Examples of potassium-sparing diuretics include:

  • Amiloride
  • Eplerenone (Inspra)
  • Spironolactone (Aldactone)
  • Triamterene (Dyrenium)

Different types of diuretics may also be combined into one pill.

A large group of medical experts known as the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure recommends that most people should try thiazide diuretics as the first choice to treat high blood pressure and heart problems related to high blood pressure. If diuretics alone aren't enough to lower your blood pressure, your doctor may also recommend adding medications such as beta blockers, calcium channel blockers, angiotensin-converting enzyme (ACE) inhibitors or angiotensin II receptor blockers to your blood pressure treatment.

In addition, doctors prescribe certain diuretics to prevent, treat or improve symptoms in a variety of conditions, such as:

  • Heart failure
  • Tissue swelling (edema)
  • Polycystic ovary syndrome
  • Certain kidney disorders, such as kidney stones
  • Diabetes characterized by frequent urination (diabetes insipidus)
  • Male-pattern hair growth in women (hirsutism)
  • Osteoporosis

Diuretics are generally safe, but do have some side effects. The most common side effect of diuretics is increased urination. This occurs most frequently in people taking loop diuretics. For most people, this side effect improves within a few weeks of taking a diuretic. People who take diuretics may also develop too much potassium in their blood (hyperkalemia) if they take a potassium-sparing diuretic, or too little potassium in their blood (hypokalemia) if they take a thiazide diuretic.

Other side effects of diuretics may include:

  • Low sodium in your blood (hyponatremia)
  • Dizziness
  • Headaches
  • Increased thirst
  • Muscle cramps
  • Increased blood sugar
  • Increased cholesterol
  • Rash
  • Joint disorders (gout)
  • Impotence
  • Menstrual irregularities
  • Breast enlargement in men (gynecomastia)
Feb. 01, 2014