Spironolactone is a medication that can reduce fluid retention. It’s often prescribed to treat high blood pressure and heart failure. It blocks the action of the hormone aldosterone, which may affect thyroid function.

Spironolactone is a prescription drug used to manage high blood pressure and heart failure, as well as treat excess aldosterone production. It acts as a diuretic and can be used to reduce swelling from certain liver and kidney issues.

Because spironolactone affects hormonal balance, it’s sometimes used to treat excess hair growth and acne in cisgender women and to reduce testosterone in trans women.

Spironolactone is an aldosterone antagonist, which means it blocks the action of the hormone aldosterone. Blocking aldosterone is one of the ways spironolactone is able to reduce blood pressure. For people with hyperthyroidism, or high levels of thyroid hormone, aldosterone is usually elevated and may promote cardiovascular inflammation.

Spironolactone has not been proven to cause hyperthyroidism, but there is some evidence that people with hyperthyroidism could potentially benefit from spironolactone.

Hyperthyroidism can lead to cardiovascular complications, such as high blood pressure, coronary artery disease, and heart failure. Spironolactone is able to inhibit aldosterone production, which is elevated in people with hyperthyroidism, thus reducing the risk of cardiac issues for these individuals.

Spironolactone has other side effects and may interfere with some medications. It’s important to have a conversation with your doctor before starting spironolactone to know what to expect.

Symptoms of hyperthyroidism to know

If not treated, hyperthyroidism can have several complications and side effects, including:

  • Osteoporosis: Hyperthyroidism can lead to osteoporosis, which causes your bones to become weak and thin. Exercise and supplements may help prevent this.
  • Atrial fibrillation (AFib): AFib is a type of irregular heartbeat that can put you at increased risk of blood clots or stroke.
  • Cancer: Thyroid cancer, or thyroid carcinoma, may develop in some people with hyperthyroidism.
  • Thyroid storm: A thyroid storm is a rare, but possibly life threatening, complication of hyperthyroidism.
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Spironolactone’s impact on thyroid hormones is mixed. Because spironolactone affects aldosterone, it also has the potential to affect thyroid hormones. However, study results vary as to how much of an impact spironolactone has on thyroid hormones.

One 2020 study involving males with Hashimoto thyroiditis, which results in an underactive thyroid gland, showed that spironolactone may have a negative effect on the condition.

Another 2020 study conducted on rats indicated that spironolactone could play a role in reducing cardiovascular disease in subjects with existing hyperthyroidism.

A 1989 study, also conducted in rats, found that high doses of spironolactone resulted in increased thyroid gland size and activity.

While it seems possible that spironolactone affects thyroid hormones, more research is needed to determine exactly who might be affected and to what extent.

Next steps

If you suspect you have hyperthyroidism, see your doctor for blood tests to confirm the condition. Common symptoms of hyperthyroidism to be aware of include:

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Spironolactone is a drug commonly used to treat high blood pressure, reduce swelling from certain medical conditions, and reduce excess aldosterone levels. It may have side effects, including leg cramps, diarrhea, and excess potassium levels.

Spironolactone has not been proven to cause hyperthyroidism, but there is some evidence that people with hyperthyroidism could benefit from spironolactone. More research is needed to know exactly how spironolactone may affect thyroid hormones.