Medically reviewed by Kristin Hall, FNP
Written by Our Editorial Team
Last updated 9/30/2022
If you’re beginning to lose your hair and have looked into treatment options, you’ve likely heard of a medication called finasteride.
Finasteride is a prescription medication that’s used to treat hair loss. It’s approved by the FDA and backed up by a large number of scientific studies showing real, measurable improvements in things like hair count and density.
Although finasteride can’t permanently cure male pattern baldness, it’s one of the most reliable, effective treatments available for slowing down hair loss and promoting hair regrowth.
Finasteride works well, but the results it produces aren’t instant. In general, you’ll need to wait a few months before you’ll be able to spot any improvements in healthy hair growth or overall hair density from finasteride.
Below, we’ve provided more information about how long finasteride takes to work, as well as the typical results timeline you can expect after starting finasteride treatment.
We’ve also discussed what you can do to make sure that you get the best possible results from treatment with finasteride, as well as potential side effects to look out for while you’re using this medication.
Before we get into the specifics of how long finasteride takes to work, let’s go over the basics of what finasteride is and how it works as a treatment for hair loss:
Finasteride is part of a class of medications called 5-alpha reductase inhibitors. It works by stopping your body from converting testosterone into dihydrotestosterone (DHT), the hormone responsible for male pattern baldness.
You can purchase finasteride as a generic prescription medication. It’s also available as the active ingredient in Propecia® and Proscar®, a prescription medication for reducing prostate growth.
Although finasteride starts blocking DHT right away, it generally takes several months for this medication to show a noticeable reduction in your rate of hair loss or improvement in your head of hair.
Many men who use finasteride see mild improvements after three to four months of use, with “final” results from treatment with finasteride typically taking approximately one year to become apparent.
Finasteride is generally more effective when it’s used with minoxidil, a topical medication that stimulates regrowth of hair by accelerating your hair’s natural growth cycle.
If you use finasteride, taking photos of your hair on a monthly basis and comparing them regularly can make it easier to monitor your progress and track any decrease in hair loss as it happens.
To understand how finasteride works as a hair loss medication, it’s important to first understand how and why male pattern baldness occurs in the first place.
Hair loss from male pattern baldness occurs due to a mix of genetic factors and the effects of an androgen hormone, or male sex hormone, called dihydrotestosterone (DHT).
DHT is an important hormone for your development as a man. Early in your life, DHT and other androgens all play significant roles in the development of your male features, from your genitals to your voice, bone structure, muscle mass and body hair.
However, as an adult, DHT isn’t so necessary for your wellbeing. Instead, it’s associated with an increase in pattern hair loss, as well as problems such as benign prostatic hyperplasia (BPH, or enlarged prostate).
DHT can attach to receptors throughout your scalp and cause your hair follicles to “miniaturize,” or stop producing new hairs. Over time, this can result in a receding hairline, a bald patch near your crown and other signs of hair loss.
Because DHT is an androgen, this form of pattern hair loss is often referred to as androgenetic alopecia.
Your body creates DHT as a byproduct of testosterone. Finasteride works by inhibiting a group of enzymes called 5-alpha-reductase and stopping your body from converting testosterone into DHT.
By stopping this conversion, finasteride significantly lowers the level of DHT in your body. This slows down -- or, in many cases, stops -- follicular damage caused by DHT and prevents male pattern baldness from becoming more severe.
The end result is a massive reduction in hair loss and a thicker head of hair, particularly around your hairline, crown and other areas with hair follicles that are sensitive to the effects of DHT.
As we’ve explained in our guide to the hair growing process, the hair follicles on your head and body all grow as part of a four-phase hair growth cycle.
This process starts with each hair growing from a root in the bottom of the hair follicle during its anagen phase. As the hair grows longer, it’s eventually pushed through your skin, allowing it to become visible. Each hair’s anagen phase, or growth phase, can last for several years.
Finasteride enters your bloodstream fairly quickly and starts reducing DHT levels as soon as it’s active in your body.
However, since it takes time for new hairs to grow to a visible length, the results from finasteride aren’t immediate. Most of the time, you’ll notice a gradual, steady improvement in your hair over the course of several months.
As soon as finasteride is metabolized by your body, it will start to reduce the amount of DHT that circulates in your bloodstream.
This means that your hair will be protected from the harmful effects of DHT just a few hours after you take your first dose of finasteride.
On average, finasteride reduces the amount of DHT in your bloodstream by around 70 percent, which is enough to significantly slow down, stop or even reverse hair loss that’s caused by male pattern baldness.
However, because it takes time for your hair to successfully make its way into the first phase of its natural growth cycle, you may not see any results right away.
During the first few months of using finasteride, you probably won’t notice much of a change in your hair. Your hairline, crown and your general level of hair thickness will probably look exactly the same as normal, with no significant improvements.
This isn’t because finasteride isn’t working properly. Instead, the lack of visible progress during the first few months is simply because your hair needs to grow before results are obvious.
During the first few months, it’s important that you continue to use finasteride each day, even if you don’t notice any results. Rest assured that the medication is working properly -- it’s just too early for its effects on your hair to be visible.
Most of the time, early results from finasteride start to become visible after around three to six months of daily use.
After taking finasteride for this amount of time, you might notice that your hair loss has slowed down or stopped, with no further visible thinning. You may also see improvements in your hair, particularly in areas such as your hairline and crown.
In a study published in the European Journal of Dermatology in 2004, researchers found that men with pattern hair loss displayed a “significant improvement” after using finasteride for 12 weeks, or just under three months.
Because your hair needs time to grow, the results after three to six months generally won’t be your “final” results from finasteride.
However, noticing an improvement after three to six months -- even if it’s relatively modest -- is generally a good sign that finasteride is starting to work for you.
After taking finasteride consistently for 12 months, you should see further improvements in your hair that build on your progress from months three to six.
Most studies on finasteride show significant, measurable increases in hair count, thickness and reduction in the hair loss process after 12 months of treatment.
For example, a 1999 study published in the Journal of the American Academy of Dermatology found that men who used finasteride over a period of one year showed a significant increase in hair count in the frontal scalp (hairline) area.
Clinical trials have also found that about 65 percent of men treated with finasteride show some degree of increased hair growth after 12 months.
Since everyone’s hair is slightly different, there are no precise results that you should expect at the 12 month mark. You may have a modest increase in hair growth that you can see when you brush your hair or look in the mirror, or significant improvements that are easy to notice.
In some cases, taking finasteride for 12 months may not have a noticeable impact on your hair’s thickness and level of growth, but will simply prevent your hair loss from worsening.
If you haven’t noticed any improvements in your hair volume or general hair growth after taking finasteride for 12 months, it’s best to talk to your healthcare provider.
If finasteride isn’t effective for you after this amount of time, further treatment may also not have a significant effect on your hair loss.
Finasteride keeps working after the 12 month mark, with most research showing that men who use the medication for the long term continue to see a reduction in hair loss and improved hair growth.
A study from 2003 looked at the results of finasteride over two years. The researchers found that men who used finasteride displayed a 14 percent improvement in hair count after one year of treatment, as well as a 16 percent improvement after two years.
An even longer study from Japan looked at the effects of finasteride on hair loss over five years of treatment. The researchers noted that 99.4 percent of men who used oral finasteride tablets during the study period showed improvements.
Put simply, the long-term effects of finasteride appear to be the same as those that occur in the short term -- a reduction in hair shedding, improved hair growth and noticeable improvements in hair thickness and scalp coverage.
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Almost all medications can cause side effects, and finasteride is no exception. Side effects from finasteride aren’t very common, with only a small percentage of men typically affected. However, they can occur, making it important to be aware of them before using this medication.
The most common side effects of finasteride are sexual side effects, such as a decreased libido (weak sex drive), erectile dysfunction (ED) and decreased ejaculatory volume.
These effects can sound alarming, but it’s important to keep in mind that sexual dysfunction only occurs in a small percentage of men who use finasteride.
For example, data from trials of finasteride shows that the most common systemic side effect -- decreased libido -- only affects 1.8 percent of men who use this medication to treat male pattern baldness.
To put this figure into perspective, the same research shows that 1.3 percent of men who used a non-therapeutic placebo also reported the same side effect during treatment.
Other mild side effects are also uncommon. For example, erectile dysfunction and a reduction in ejaculatory volume were reported by 1.3 and 1.2 percent of men who used finasteride in clinical trials, respectively.
Like decreased libido, these side effects were also reported by men that used a non-therapeutic placebo treatment, suggesting that some cases may not be caused by finasteride itself.
Other side effects that are associated with finasteride include testicular pain, clinical depression and, in rare cases, changes in breast size, nipple discharge, rash, itching, hives, swelling of the face and/or lips, as well as difficulty breathing and/or swallowing.
Overall, finasteride’s adverse effect profile is fairly mild, with few side effects that occur in more than a small percentage of users.
While serious side effects from finasteride aren’t common, it’s important to tell your healthcare provider if you experience persistent and/or bothersome side effects while using finasteride to treat hair loss.
Your healthcare provider may suggest making changes to the way you use your medication or switching to a topical hair loss treatment, such as topical finasteride.
Make sure to closely follow your healthcare provider’s instructions and inform them if you have any side effects or concerns about your wellbeing while using finasteride.
For the most part, using finasteride is simple -- just take one pill every day and pay attention to any changes in your hairline that occur over the next few months.
However, like with other medications, there are several things that you can do to maximize your results from finasteride, keep track of your progress and maintain your new hair after you notice improvements. Try to:
Take finasteride every day. Finasteride is designed for daily use. Take your medication every day, even if you don’t notice any changes in your hairline, hair density or thickness when you first start using it.
Skipping finasteride doses or only using the medication every now and then may reduce its effectiveness and compromise your results.
Use finasteride and minoxidil together. Although finasteride is effective on its own, it’s more effective when used with minoxidil -- an over-the-counter medication that works by stimulating hair growth.
If you have noticeable hair loss and want the biggest possible improvement in your hair growth and density, consider using both of these medications together.
Use a hair loss prevention shampoo. DHT-blocking shampoos, such as our Thick Fix Shampoo, help to break down buildup on your scalp that can damage your hair follicles and worsen hair loss.
Try adding a hair loss shampoo to your hair care routine while you use finasteride and minoxidil to stimulate growth.
Take photos to monitor your results. Because you see yourself in the mirror virtually every day, seeing the small, subtle changes in your hair that can occur over the course of several months of finasteride use isn’t always easy.
To track your progress, take a photo of your hairline, crown and other areas affected by hair loss every month. Try to use similar or identical lighting conditions so that you have an accurate view of your hairline, hair count and thickness over time.
After you get results, don’t stop using finasteride. Keep taking finasteride, even after you see results. If you stop taking finasteride, your DHT levels will rise and your hair loss may start to worsen again.
Waiting for results from a medication for hair loss can be frustrating, but it’s important to remain patient after you start using finasteride.
Although finasteride starts working immediately, your hair follicles need time to begin producing new hairs. This means that you’ll usually need to wait for three to six months before seeing any changes in your hairline or hair thickness after starting treatment with finasteride.
Worried about losing your hair? We offer a large range of hair loss treatments online, including FDA-approved medications such as finasteride and minoxidil.
You can get started by taking part in an online hair loss consultation, or learn more about your options for treating male pattern baldness and stimulating hair growth in our guide to what you should take to prevent hair loss.