How Long Does it Take Finasteride (Propecia) to Work For Hair Loss? Plus 7 More FAQs

There are many different factors that can cause hair loss, such as stress or autoimmune disease. But the most common cause of hair loss is genetic. It’s officially called androgenetic alopecia, but it’s often referred to as male- or female-pattern baldness. And finasteride (Propecia) is a common treatment option for it.

Finasteride is most often prescribed for males. But it’s sometimes used off-label for females, too. If your prescriber recommends finasteride, it’s common to wonder what it actually does to treat hair loss. And how long does it take for finasteride to work?   

1. How does finasteride work?

Finasteride belongs to a group of medications called 5-alpha reductase inhibitors. To understand how it works, we need to start with testosterone.

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Testosterone is a hormone that’s responsible for growth and muscle mass in males. It’s also used to form another hormone, called dihydrotestosterone (DHT). And while DHT plays several important roles in the body, it’s also known to cause hair loss.

DHT is formed from testosterone by an enzyme (protein) called 5-alpha reductase. Finasteride blocks this enzyme, which lowers DHT levels and helps prevent hair loss.

2. How long does it take finasteride to work for hair loss?

Finasteride starts lowering DHT levels right away. Clinical studies show a 65% decrease in DHT levels within 24 hours of the first dose. This helps prevent further hair loss.

However, hair regrowth happens over time, so it takes longer to start seeing visible results from finasteride. In studies, results were seen as early as 3 months after starting finasteride treatment. More significant improvements were seen at 6 and 12 months.

Some people don’t have visible results in the first year of finasteride treatment. But a long-term study found that if you keep taking it, visible results will likely appear later on.

3. Can finasteride regrow hair?

Yes. Long-term finasteride treatment can help increase the amount of hair you have. The majority of hair regrowth seems to happen in the first 2 years of taking finasteride. But keep in mind that continued treatment still prevents further hair loss.

Finasteride also seems to work better at regrowing hair the earlier you start taking it. Studies suggest it's best to start taking finasteride as soon as you notice hair loss. It’s also likely to be more effective for balding that starts at the crown of the head than at the hairline.

4. Is there anything you can do to make finasteride work faster?

There’s not a way to make finasteride work faster. But as mentioned, you’ll have better results the sooner you start the medication once hair loss starts.

You may also want to talk to your care team about combining finasteride with other treatments. Adding topical minoxidil or laser therapy to finasteride may help prevent hair loss and regrow hair. Platelet rich plasma (PRP) injections have also been shown to be effective when combined with finasteride treatment in studies.

Good to know: Higher doses of finasteride (5 mg) are used to treat an enlarged prostate due to a condition called benign prostatic hyperplasia. But higher doses aren’t more effective than lower doses (1 mg) for hair loss. And higher doses of finasteride also have a greater risk of side effects. So it’s best to stick with 1 mg of finasteride for hair loss unless your prescriber tells you otherwise.

5. Does finasteride affect testosterone levels?

Finasteride stops some testosterone from being turned into DHT. As a result, you may have an increase in testosterone levels (up to 25%) when you start taking it. But this increase doesn’t seem to cause any issues and may not have noticeable effects.

However, finasteride may cause erectile dysfunction and low libido (sexual desire) in some men, despite the fact that it increases testosterone levels. It’s not clear why this happens, and it’s less common with low finasteride doses. But let your care team know if sex-related side effects are an issue for you. A different hair-loss treatment may be a better option.

6. How long does finasteride stay in your system?

Finasteride doesn’t last very long in your body. It will take about 30 hours (a little over 1 day) to clear it after your last dose.

Keep in mind that if you stop taking finasteride, its DHT-blocking effects will also stop. Your DHT levels will return to normal within about 14 days (2 weeks). And your hair loss will likely resume, as well.

7. How long do you have to take finasteride?

You need to keep taking finasteride daily in order for it to keep working. As mentioned, once you stop taking it, your DHT levels will go back up and hair loss will resume. Most people will lose any regrown hair within 12 months of stopping finasteride treatment.

8. Is finasteride safe to take?

Finasteride is generally considered safe. But, it’s a good idea to talk to your care team about possible risks and side effects before you take it. This will help you make an informed decision as to whether it’s the right treatment option for you.

The most common finasteride side effects include erectile dysfunction and low libido. Depression is also possible, as well as enlarged breasts in males. These side effects are more common with higher doses of finasteride. But they’re still possible at any dose.

What’s more, these side effects may persist even after you stop taking finasteride. This wasn’t common in clinical studies, but it seems that this issue, known as post-finasteride syndrome, may be more common than previously thought.

Finasteride may also raise the risk of a certain type of severe prostate cancer. But it also lowers the risk of prostate cancer in general. So the overall risk remains unclear.

Your medical care team can help you decide if finasteride is a safe treatment option for you, based on your medical history and other health conditions. 

Good to know: Finasteride can interfere in the growth and development of a fetus. Avoid taking — or even touching — finasteride tablets if you’re pregnant.

How to save on finasteride

There are ways to save on finasteride, which is available as both a brand-name and generic medication. Generic finasteride’s price at certain pharmacies is as low as $9.30 with a free GoodRx discount.

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Written by:

Jill Barat, PharmD

Jill Barat, PharmD has nearly 10 years of experience as a pharmacist, including serving as the pharmacist in charge at an independent sterile and non-sterile compounding pharmacy. She also worked as the head of medical content for a telemedicine company.

Edited by:

Stacia Woodcock, PharmD

Stacia Woodcock, PharmD, is a pharmacy editor for GoodRx. She earned her Doctor of Pharmacy degree from the University of Kentucky and is licensed in New York and Massachusetts.

Reviewed 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.

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