What Is Propecia: Uses, Side Effects & How It Works

Written by Our Editorial Team

Propecia® is an FDA-approved prescription medication for male pattern baldness. It contains the active ingredient finasteride and works by stopping the conversion of testosterone into the hormone dihydrotestosterone (DHT), which causes hair loss or a receding hairline in men.

If you’re starting to lose your hair and want to stop it from worsening, your healthcare provider may suggest using Propecia either on its own or with a topical treatment such as minoxidil.

Propecia works well as a treatment of male pattern hair loss — a fact that’s backed up by numerous studies showing the medication can slow down, stop and even reverse the effects of male pattern baldness.

Read on to learn more about Propecia, including how it works as a treatment for pattern hair loss in men.

You’ll also find answers about generic Propecia such as common side effects, how you can access the medication and more.

What Is Propecia?

Propecia is a prescription medication used to treat androgenetic alopecia, or male pattern baldness.

Currently, Propecia is only available in tablet form. Each tablet contains 1mg of finasteride, the medication’s active ingredient.

The FDA approved Propecia in 1997. Prior to this, the active ingredient finasteride was used as a treatment for benign prostatic hyperplasia (BPH, or enlarged prostate).

How Does Propecia Work?

Finasteride (the active ingredient in Propecia) belongs to a class of medications called 5-alpha reductase inhibitors, or 5ARIs.

It works by preventing your body from converting testosterone into the more potent androgenic hormone dihydrotestosterone (DHT).

To understand what this means, it’s important to quickly cover the basics of how and why male pattern baldness occurs.

Contrary to what many people think, male pattern baldness isn’t caused by wearing a hat that’s too tight, washing your hair too often or using too many styling products.

Instead, male pattern baldness develops as a result of a combination of genetic factors and the effects of DHT.

Your body produces DHT by converting a small percentage of its freely circulating testosterone — all via an enzyme called 5 alpha-reductase.

If you’re genetically predisposed to male pattern baldness, the DHT that’s created as a result of this process can bind to receptors in your scalp and gradually cause your hair follicles to shrink and stop producing new hairs.

You can learn more about DHT and its effects on your hair follicles in this full guide to DHT and male pattern baldness.

Not everyone is equally sensitive to the effects of DHT, which is why some guys go bald in their 20s or 30s, while others are able to maintain a full head of hair well into old age.

So, how does finasteride fit into this? As a 5-alpha reductase inhibitor, finasteride prevents your body from converting testosterone into DHT.

This lowers the amount of DHT that’s able to bind to receptors in your scalp and protects your hair follicles from DHT-related damage.

Does Propecia Work for Hair Loss?

Simply put, yes. Propecia — or, more specifically, its active ingredient finasteride — has been the focus of research for decades, with several studies finding that it can slow down, stop and even reverse the effects of male pattern baldness.

More recent studies on finasteride have looked at the effects of finasteride on hair growth and male pattern baldness over an even longer period.

In a study published in the journal Clinical Research and Trials in 2019, a team of researchers in Japan looked at the effects of finasteride in men who’d been using the medication over a period of 10 years.

They found that 99.1 percent of the study participants showed no worsening of hair loss over the full 10-year period they had been using finasteride.

Even more impressively, 91.5 percent of the men showed improvements in hair growth over the same period.

The researchers concluded that finasteride showed “high efficacy and safety” as a treatment of male pattern hair loss (androgenetic alopecia).

How Long Does It Take for Propecia to Work?

The finasteride in Propecia starts blocking DHT right away, although it can take several months for it to produce any noticeable change in your hair.

Most people start to notice results from Propecia after three to four months of daily use. As the medication starts to work, you may notice:

Your hair loss slows down, with fewer stray hairs visible on your pillow case, sheets or in your shower drain.
Improvements in your hair’s thickness and density, especially around your hairline or at your crown (the area at the top of your head).

Even though Propecia is effective for most guys, it won’t completely stop your hair from falling out.

Your hair goes through a natural multi-phase hair growth cycle, meaning it’s common and normal to shed some hair even if Propecia is working to prevent male pattern baldness.

Make sure to take finasteride every day, even if you don’t notice any change in your hair during the first few months of treatment.

Is There a Generic Version of Propecia?

Yes. Propecia was protected by an active patent throughout the 1990s and 2000s. However, like with many older medications, the patent on Propecia has since expired and finasteride, its active ingredient, is now available as a generic medication.

Generic finasteride is available in the same 1 mg per tablet dosage as brand-name Propecia. It’s equally as effective at treating hair loss as Propecia, making it an option worth considering if you want to save money while combating male pattern baldness.

You can obtain generic finasteride online, following a consultation with a licensed healthcare provider who will determine if a prescription is appropriate.

Propecia vs. Proscar®

If you’ve searched online for information about Propecia, you may have seen references to a similar medication called Proscar.

Proscar is a medication for benign prostatic hyperplasia. It contains the same active ingredient as Propecia, but at a higher dosage (each tablet of Proscar contains 5mg of finasteride, versus 1mg for each Propecia tablet).

Your healthcare provider will typically prescribe Proscar or its generic equivalent if you have an enlarged prostate. Proscar is not typically used as a treatment for male pattern baldness.

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Can Propecia Cause Side Effects?

Propecia is a popular medication used by millions of men in the United States and around the world to treat pattern hair loss. And most who use Propecia don’t experience significant issues.

However, like all medications, Propecia can potentially cause side effects.

Currently, the most common side effects of Propecia are sexual issues such as erectile dysfunction (ED), ejaculation disorder (a decreased volume of ejaculate, the amount of semen) and a reduced interest in sex.

According to the FDA documentation for Propecia, these common side effects were reported by between 1.2 and 1.8 percent of men who used Propecia in clinical trials.

Although uncommon, other adverse effects have been reported with Proscar, which contains a higher-strength version of finasteride used to treat prostate enlargement.

These side effects are male breast growth (gynecomastia) and breast tenderness or pain, which could create a male breast cancer risk. Finasteride has sometimes been linked with testicular pain, depression, and infertility, as well.

While these issues may sound alarming, though, it’s important to keep in mind that they affect only a tiny percentage of people who use Propecia, Proscar or generic finasteride.

In rare cases, Propecia may cause allergic reactions. If you experience any of the following symptoms, contact your healthcare provider or seek medical assistance as soon as possible:

Skin rash, itching and/or hives
Swelling that affects your lips and/or face
Difficulty breathing or swallowing
Changes in the breasts, such as growth, pain, lumps or nipple discharge

Propecia and other medications that contain finasteride may cause finasteride interactions when used with other medications.

Make sure to inform your healthcare provider about all medications you currently take or have recently taken before using Propecia.

Propecia is only approved for use in men. In fact, research has found that finasteride can contribute to birth defects when used during pregnancy.

Pregnant women should not take Propecia or other medications that contain finasteride, or touch broken or crushed Propecia tablets.

How Do You Get Propecia?

Propecia is only available with a valid prescription, meaning you’ll need to talk to a healthcare provider in order to purchase and use it.

If you’ve noticed the early signs of male pattern baldness and want to use Propecia to prevent further hair loss, it’s best to talk to your healthcare provider.

You can purchase generic finasteride online, following a consultation with a licensed healthcare professional who will determine if a prescription is appropriate.

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Is Propecia Right for You?

Propecia — which contains finasteride — is an effective medication for male pattern baldness that can slow, stop or even reverse hair loss.

For optimal results, you’ll want to use finasteride with the topical hair loss medication minoxidil and other science-based hair loss treatments.

And for optimal results in your quest for hair regrowth, it’s best to connect with a healthcare professional to learn more about your individual hair needs.