Spironolactone is a prescription medication that was first approved by the U.S. Food and Drug Administration (FDA) in 1960. Spironolactone is a unique type of water pill in a class of medications called potassium-sparing diuretics.

Many water pills work in the kidneys to eliminate extra water from the body along with sodium and potassium. Spironolactone works differently. It blocks a hormone called aldosterone, which causes the body to remove water along with sodium but reduces how much potassium is removed.

Spironolactone has several FDA-approved uses for which it’s prescribed, including:

  • heart failure
  • swelling or edema caused by heart failure, liver disease, or kidney disease

It’s also prescribed for:

  • treating high blood pressure
  • preventing low potassium
  • lowering levels associated with hyperaldosteronism (excessive secretion of the hormone aldosterone)

In addition to its diuretic effects, spironolactone also blocks androgen receptors. This means that it can decrease the effects of testosterone in the body.

Because of this unique effect, spironolactone is often used off-label for conditions that involve excess testosterone. Some of these include:

No scientific research has evaluated spironolactone specifically for weight loss. But it makes sense that spironolactone might reduce weight in some people, especially those with fluid retention.

Spironolactone works as a diuretic, which means that it causes the body to remove extra fluid. Reducing fluid in the body can result in body weight loss.

It’s important to keep in mind that this kind of water-weight loss is not the same as healthy weight loss due to reduction of body fat or body mass. These require good nutrition and exercise.

Weight loss due to fluid reduction might not be long-lasting. Decreasing body fluid too much can result in dehydration. Once body fluid levels return to normal, the weight will return.

Spironolactone has been studied in women who have bloating and swelling due to premenstrual syndrome (PMS).

Spironolactone can cause significant improvement in these symptoms by reducing fluid retention. As a result, some doctors prescribe spironolactone for women who develop bloating and weight gain from water retention due to PMS.

Spironolactone comes in 25-milligram (mg), 50 mg, and 100 mg tablets. Your doctor will tell you what dosage is right for you

  • For heart failure: 12.5 to 25 mg, once or twice daily, is typically used.
  • For swelling or edema caused by heart failure, liver disease, or kidney disease: Doctors typically prescribe doses of 25 to 100 mg, once or twice daily.
  • For high blood pressure: Doses are typically 50 to 100 mg daily.
  • For hyperaldosteronism: Doses up to 400 mg daily may be used.

Spironolactone is generally safe to take. Some people can experience side effects such as:

  • diarrhea
  • stomach cramps
  • nausea
  • vomiting
  • headache
  • dizziness
  • irregular menstrual bleeding
  • breast swelling and pain in men
  • skin rash
  • leg cramps
  • high potassium levels

In some cases, people who take spironolactone can become dehydrated. Be sure to drink adequate water while taking spironolactone. Watch for signs of dehydration, including:

  • excessive thirst
  • infrequent urination
  • dark-colored urine
  • confusion

Spironolactone is a prescription medication. It works as a diuretic to eliminate extra water from the body along with sodium, but it doesn’t reduce potassium.

Spironolactone also blocks androgen receptors. Because of its unique effects, spironolactone has a wide variety of FDA-approved and off-label uses.

There is no evidence that spironolactone works specifically for weight loss. But spironolactone might help reduce weight that’s related to fluid retention, especially in women with bloating and swelling due to PMS.

If you experience weight gain due to PMS, you may want to talk to your doctor about spironolactone.