Finasteride Side Effects in Women

Approximately 40 percent of women develop female pattern hair loss (FPHL) by the age of 50. Yes, really.

FPHL is also sometimes called androgenetic alopecia. 

Which means, amongst other things, there are a large number of women out there looking for an effective treatment to stop their hair loss. 

If you are one of these women, perhaps you’ve heard of finasteride. It’s a medication often used by men to treat male pattern baldness. 

While the FDA has not approved finasteride for use by women, there are some women who take it for hair loss. There’s even research that suggests it can be a helpful tool to combat female pattern hair loss. 

Interested in taking oral or topical finasteride? With any medication you take, it’s important to understand what the side effects are before taking it. 

Finasteride requires a prescription and is a 5-alpha reductase inhibitor, which works by blocking certain hormones. Most commonly, it’s used to treat male pattern baldness in, yes you guessed it, men. 

To understand how finasteride works, you need to understand a bit about pattern baldness. 

Both men and women have testosterone in their systems. In women, it helps with reproductive and non-reproductive functions.

But when testosterone attaches to something called androgen receptors in the hair bulb and the dermal papilla (something that regulates hair growth), it can shrink hair follicles and cause hair loss. 

This free-floating testosterone might also be converted into something called dihydrotestosterone (DHT), which can attach to androgen receptors and also cause hair loss.

Finasteride stops testosterone from turning into DHT, so you have less DHT in your scalp.

Taking 1mg of finasteride daily has been found to reduce DHT in the scalp by upwards of 60 percent in men — emphasis on men. 

Oral finasteride is the most common form of this medication. The brand name version of finasteride is called Propecia®. There is also a topical version but it’s not FDA-approved. That said, topical finasteride has also been found to help with hair growth. 

Though not FDA-approved to be taken by women, there is some research that suggests oral or topical finasteride could be beneficial for female pattern baldness. 

In one small study of 37 women, 62 percent of the women saw some improvement in hair loss and hair density after taking a 2.5/mg oral dose of finasteride for a year. One thing to note: These women also took birth control pills, making it impossible to solely attribute the hair growth to finasteride. 

Another study focused on 87 pre- and post-menopausal women taking 5 mg/day of oral finasteride for over a year. By the end of the study, most of the women noticed denser hair.

It’s worth noting the dosage of finasteride in both of these studies. It seems to be important. There was a study published in 2000 in which 137 postmenopausal women with FPHL took only 1mg/day of oral finasteride and didn’t notice any benefits. 

While these studies of successful finasteride use in women are small and more research needs to be done, they point to finasteride being able to possibly treat FPHL. But you may be wondering: is finasteride safe for women? 

First, it’s worth noting that because finasteride has not been FDA-approved for women, there have been no big clinical trials looking at the effects it may have on females. Because of this, it cannot be said that finasteride is totally safe for women. 

However, in the studies mentioned above, no one reported any serious side effects or dangers of using oral or topical finasteride.

A review of research also found no significant side effects over the course of months of treatment. Though this review did find that some women who used finasteride reported the following common side effects: 

• A low sex drive

• Irregular menstruation

• Acne

• Headaches

• Dizziness

• Folliculitis

• Increased body hair growth

Rarely, finasteride has caused more serious side effects to occur. Including:

• Increased breast tenderness or breast swelling, lumps, pains or nipple discharge

• Skin rash and/or hives

• Itching

• Swelling of the face

• Difficulty swallowing or even breathing

If you take finasteride and experience any of these things, you should contact a healthcare professional immediately. 

Finally, pregnant women or women trying to get pregnant should not take finasteride. The medication affects testosterone, and because of this it can cause birth defects to male genitalia. Even exposure to a broken finasteride tablet is ill advised.

Female pattern hair loss (or androgenetic alopecia) is relatively common — nearly half of women will develop it by the time they turn 50. 

There are a variety of ways FPHL can be treated. One way is through oral or topical finasteride. This prescription medication is more commonly used for male pattern baldness. While it’s FDA-approved for this reason for men, it is not FDA-approved for women. 

Even still, there’s some research that shows that certain doses of the course of months of treatment can help with hair loss in females — particularly pre- and postmenopausal women. More research still needs to be done to fully say finasteride works for women. 

Women who take this medication may experience sexual side effects, acne, headaches, irregular periods and more. Very rarely, more serious adverse effects (like trouble breathing and hives) can be experienced. Pregnant women should never take finasteride; it may cause birth defects.

If you are interested in taking finasteride to treat androgenetic alopecia, the first thing you should do is speak with a healthcare professional. They will be able to give you medical advice and tell you if it may help your hair loss and go over any other adverse effects that could occur from taking it.