Proscar vs. Propecia: How Do These Finasteride Medications Compare?

The medications Proscar and Propecia are both brand names for finasteride — but they are not one in the same. For starters, they come in different dosages and have different FDA-approved uses.

Proscar is FDA-approved benign prostatic hyperplasia (BPH) and Propecia is approved to treat a specific type of hair loss in men (androgenetic alopecia). But since they share the same active ingredient, it’s a common question as to whether Propecia and Proscar are interchangeable. In this article, we’ll answer that question and cover what else you need to know about finasteride.

What’s finasteride?

Finasteride is in a group of medications called 5-alpha reductase inhibitors. These medications work by lowering the amount of dihydrotestosterone (DHT) in the body. 

DHT is a male sex hormone (androgen). It’s made from testosterone. When DHT levels are high, it can cause an enlarged prostate and hair loss. Finasteride blocks the normal process of testosterone conversion to DHT. It’s a first-choice medication for androgenetic alopecia. It’s also a treatment option for BPH.

Proscar can take up to 6 months to help with BPH. And you may need to take Propecia for at least 3 months before seeing hair growth. 

What’s the difference between Proscar and Propecia?

The main difference between Proscar and Propecia is how much finasteride is in each medication. 

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Proscar is available as a 5 mg tablet. It’s taken once a day and can be combined with other medications (called alpha blockers) to treat BPH. Propecia is available as a 1 mg tablet. 

Because Proscar has more finasteride in each tablet, it’s more likely to cause side effects than Propecia.

Are Proscar and Propecia interchangeable?

No. Both medications are usually taken once a day and contain the same active ingredient of finasteride. But they’re not directly interchangeable since they contain different amounts of finasteride per tablet.

Your healthcare provider will recommend a specific dose of finasteride based on what health condition you’re trying to manage. For BPH, your provider may prescribe Proscar 5 mg once daily. For hair loss, your provider may prescribe Propecia 1 mg once daily.

Technically, five tablets of Propecia 1 mg is equivalent to one tablet of Proscar 5 mg. But taking five tablets at a time would be less convenient and more costly. You should only take medication in the exact way your healthcare provider prescribes it.

What are the side effects of Proscar and Propecia? 

Proscar and Propecia have similar side effects.

But a single dose of Proscar contains more finasteride than Propecia, and it’s more likely to cause side effects. In fact, some side effects reported with Proscar were not reported with Propecia. 

Common side effects

Below, we’ll look at the most common side effects people reported in clinical trials of Proscar and Propecia. These side effects occurred in the first year of treatment with these medications.

Mild side effects may go away with continued use of the medication. In clinical studies of Proscar, sexual side effects, like erectile dysfunction, lowered libido, and ejaculation problems, weren’t significant after the first year of treatment. This means that people taking placebo (a pill with nothing in it) experienced these side effects just as often as people taking Proscar. 

If any side effects of Proscar or Propecia are bothersome to you, let your healthcare provider know.

Serious side effects

Proscar and Propecia can cause more serious problems in certain groups of people.

Pregnant women or people who have the ability to become pregnant shouldn’t take Proscar or Propecia. It’s best to even avoid touching or handling Proscar or Propecia, especially if the tablets are broken or crushed. These medications can cause abnormal development of your baby.

Finasteride products may also raise the risk of prostate cancer in certain men aged 55 years or older. And in younger men between 18 to 41 years old, finasteride products can lower prostate-specific antigen levels (PSA). A PSA blood test helps screen for prostate cancer. Lowered PSA levels may mask the development of prostate cancer.

If you’re concerned about serious side effects from Proscar or Propecia, talk to your healthcare provider.

How much do Proscar and Propecia cost?

Both Proscar and Propecia come in brand-name and generic versions. The generic versions are available at a fairly low cost. Finasteride products are usually covered by insurance when used for BPH, but they’re not usually covered when used for hair loss. So a free GoodRx coupon may be especially helpful if you have a prescription for Propecia. 

With a free GoodRx coupon, generic Proscar may cost less than $6 for 30 tablets at certain pharmacies. For 30 tablets of generic Propecia, a GoodRx coupon may lower the cost to about $6 in some locations. 

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Written by:

Austin Ulrich, PharmD, BCACP

Austin Ulrich, PharmD, BCACP, is a board-certified ambulatory care clinical pharmacist. In his early career, he provided direct patient care in a variety of settings, including hospital and community pharmacies, and in a primary care clinic as a clinical pharmacist.

Edited by:

Amy B. Gragnolati, PharmD, BCPS

Amy Gragnolati, PharmD, BCPS, is a pharmacy editor for GoodRx. Amy currently holds her pharmacist license in Georgia and California.

Reviewed by:

Christina Aungst, PharmD

Christina Aungst, PharmD, is a pharmacy editor for GoodRx. She began writing for GoodRx Health in 2019, transitioning from freelance writer to editor in 2021.

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