What Is Spironolactone?
Spironolactone is a medication that was originally approved by the Food and Drug Administration (FDA) for use in patients with swelling due to heart failure, liver failure, low potassium levels, and other medical conditions.  However, spironolactone has been used off-label in the treatment of female pattern hair loss, also known as androgenetic alopecia.
Spironolactone is also known by the brand name Aldactone.
How Does Spironolactone Work?
Spironolactone has several modes of action.
Not related to treating hair loss
Spironolactone works on the kidneys’ ability to exchange potassium and sodium to increase the loss of sodium and water, acting as a diuretic. It also increases retention of potassium which is why it is known as a potassium-sparing diuretic.
Related to hair loss
Spironolactone also has two anti-hormonal effects. First, it blocks the body’s ability to convert testosterone to the hormone dihydrotestosterone (DHT). Second, it blocks the effects that DHT can have on hair. It has been shown that increased levels of DHT are associated with hair loss in women.
What Hair Loss Conditions Does Spironolactone Treat?
Physicians may use spironolactone off-label to treat hair loss that is related to excessive hormones – in particular, hair loss known as female pattern hair loss. Small studies in female pattern hair loss have shown that among women that have taken spironolactone, approximately 75 to 88% had stabilization of their hair loss.[3,4] In one of the studies, women also took another hormone blocker called cyproterone, so the study did not isolate the effects of spironolactone.
Since spironolactone works on hormone-related hair loss, it is not likely to be helpful in other forms of hair loss that are not hormone-dependent, such as alopecia areata or telogen effluvium for example.
How Is Spironolactone Administered?
Spironolactone is an oral medication that is taken daily. The doses can range from as low as 25 mg up to 200 mg daily. The actual dose that is used should be discussed with a physician.
What Are the Common Side Effects and Risks of Spironolactone?
Spironolactone’s most common side effects include the following:
- Urination: Since the medication is a diuretic, it can increase the need to urinate.
- Vaginal spotting
- Breast tenderness
- Headaches: Drinking water regularly may reduce these headaches in some women.
- Increased potassium levels: Since this medication is a potassium-sparing diuretic, it can increase potassium levels. In healthy women younger than 45 years of age, researchers showed that checking potassium levels in the blood while taking the medication was not necessary. A practitioner may still elect to check potassium levels regularly.
The medication should be used carefully or not used at all in those with kidneys that do not work normally, as this can lead to dangerously high potassium levels.
Spironolactone is graded as a class C pregnancy medication, indicating that a risk to a developing fetus cannot be ruled out. It is possible that spironolactone causes feminization of a developing fetus because it blocks the conversion of testosterone to DHT and blocks the function of DHT.
Spironolactone is considered acceptable to use while breastfeeding.
What Else Should You Know?
If you tend to be very active in athletics and consume large amounts of potassium replenishing drinks or foods, you should let your physician or practitioner know.
For any drugs discussed here, please consult the drug package insert for complete prescribing information and for complete information regarding side effects.