Does Propecia (Finasteride) Work?

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I personally tried Propecia for over a year when I first started losing my hair, and in this article I’ll explain exactly how effective I and other men have found it to be, so that you can make an informed decision on using it.

This article is for educational purposes only, and you should speak to your doctor before starting treatment. It is, after all, a prescription-only medication, and one that should not be started without careful consideration.

In this article I’ll cover:

  1. How it works
  2. What to expect when taking it for the first time
  3. How and when to take it
  4. Results you can expect
  5. When to stop taking it
  6. Potential side effects
  7. Other options to try if it doesn’t work for you
  8. Conclusion

How It Works

Finasteride is the active ingredient in the popular hair loss drug Propecia. This was originally developed by pharmaceutical giant Merck to treat male prostate enlargement, and in 1997 was approved by the FDA as a treatment for male androgenetic alopecia (which is the scientific term for male pattern baldness) (1).

Androgenetic alopecia accounts for well over 95% of cases of hair loss in men and is thought to be caused by a sensitivity to the male hormone dihydrotestosterone, which is usually abbreviated to DHT. DHT is believed to progressively shrink the genetically susceptible hair follicles on the frontal and vertex area of the scalp, in a process called hair follicle miniaturization. Eventually the follicles shrink to such a degree that the hair shaft doesn’t even protrude from the scalp, with the result that it goes completely bald.

DHT is synthesized in our body via testosterone, but for this chemical reaction to take place an enzyme called 5-alpha-reductase is necessary. In the absence of 5-alpha-reductase, the production of DHT in the body plummets to near zero levels. Finasteride works by inhibiting this enzyme, which it does by binding to the enzyme and rendering it inactive (2). With 5-alpha-reductase thus inhibited, DHT levels in the body plummet, the miniaturizing hair follicles enjoy a respite from the constant DHT attack, and the hair follicle miniaturization process is paused, and often even partially reversed.

What to Expect When Taking It for the First Time

Don’t expect miracles from finasteride, and certainly don’t expect to see overnight results. Because hair growth is subject to the lengthy hair growth cycle, you can expect to see little in the way of results for the first 3 months. After the 3-month mark you can expect the first signs of regrowth, which will become more pronounced at 6 months. You get your final results with finasteride at around the 12-month mark: after that point you are very unlikely to grow further hair.

One thing to look out for if you’re taking finasteride for the first time is the appearance of side effects, which we will cover in more detail later on.

How and When to Take It

The recommended dosage is 1mg a day, which translates to one pill a day. You can take it any time of day, though ideally you want to be taking it the same time every day. In the event that you forget to take your pill one day, do not attempt to compensate by taking two pills the following day. Just continue to take your daily pill as if you had never missed a dose. You can take it on an empty or full stomach; it makes no difference.

A popular method of procuring finasteride at a lower cost is to buy the version that is sold for prostate enlargement. This comes in 5mg pills instead of the 1mg pills for hair loss. The brand name of the prostate enlargement version is Proscar, though there are now countless generic alternatives on the market. A 5mg pill of Proscar (or its generic equivalent) will typically cost the same or less than its 1mg cousin, meaning if you cut the pill in five parts you have effectively reduced your treatment cost fivefold.

Results You Can Expect

The strength of Propecia lies in its ability to stop further hair loss for most men (3). The majority of studies agree that between 80-90% of men will stop losing hair on Propecia, and that this effect will last for a minimum of five years, if not longer. In other words your body does not become tolerant to the effects of finasteride, and to the degree that it does this is a very slow process.

When it comes to regrowing hair, the results are far more modest. Around two thirds of users will see some regrowth, though this will typically be in the region of 10% for thinning parts of the scalp. The crown or vertex area of the head will generally respond better compared to frontal areas, though this is true for most hair loss treatments, and is not unique to finasteride. At any rate, this figure of 10% translates to barely visible regrowth in most cases.

With regards to parts of the head – and particularly the frontal area – that have gone completely bald, finasteride can do nothing. In other words once the follicle miniaturization process has progressed to the point where the scalp is completely bald and shiny, then all the finasteride in the world will not regrow any hair. The only realistic option for those areas is a hair transplant.

Something that bears emphasizing is that like most other hair loss treatments, be they pharmaceutical or botanical, results only last as long as the treatment. Though there is no consensus on the underlying root causes of hair loss (in other words why DHT leads to hair loss in certain parts of the scalp and in particular individuals), few would disagree that finasteride does not address them. Instead it temporarily blocks DHT, something akin to taking an aspirin to treat a headache. As soon as the effects of the aspirin wear off, the headache resumes. Similarly with finasteride: when you stop treatment, any hair you have regrown will fall back out again within 3-6 months, and your hair loss will resume its normal course.

When to Stop Taking It

Perhaps the most common mistake that users make is not allowing finasteride enough time and discontinuing treatment due to impatience. Just like you lost your hair very gradually in the first place, you will also regain it very gradually. As we mentioned earlier, you need at least 3 months to see the first signs of regrowth, and a full 12 months for the more or less final results. So if you’re not happy with the results after this time – and especially if your hair loss has continued unabated- you should stop treatment.

And of course, the other scenario where you want to consider stopping finasteride is if you develop side-effects. More on that below.

Potential Side Effects

Finasteride has now been on the markets for decades, meaning we have a decent idea of its safety profile and side-effects, though there are still some controversies which we’ll get into shortly (4).

Because finasteride is not a targeted medication that acts at the level of the hair follicle but instead blocks DHT systemically, the side effects will not manifest at your scalp. Instead, to the degree that you do get side effects, these will tend to be of a hormonal/sexual nature. The most common side effects are loss of libido and erectile dysfunction, which can range from slightly less hard erections to – rarely – complete impotence. The percentage of men who will develop these side-effects varies dramatically from study to study, ranging from 3% or less all the way to 8% or more. Another common side effect is gynecomastia, which is the swelling and tenderness of the breast tissue underneath the nipple area. If this is allowed to persist it can become permanent, meaning it can only be corrected with surgery.

These side effects can take a few days to weeks or even months to manifest after you’ve started treatment. When they do appear, and depending on their severity, there are two basic options that you can discuss with your doctor: a) reduce the dosage or b) stop treatment altogether. When it comes to lowering the dosage, believe it or not there is solid evidence that a dosage as low as one fifth the recommended 1mg daily can stop hair loss, while dramatically reducing the risk of side effects (5). So after consultation with your doctor you can switch to the lower dosage and see if the side effects persist. If they do, there is no option but to stop treatment.

Upon discontinuing treatment, the sexual side effects should all go away. Finasteride has a very short half-life, and after a few weeks it will have left your system without a trace. Unfortunately, there is a small minority of users for whom the side effects will persist – or even exacerbate –when the patient comes off finasteride. When this happens it is usually accompanied by other symptoms like fatigue, depression, and anxiety, but as I said this will only affect a small minority of users. Why this phenomenon happens is still a mystery and something which is shrouded in great controversy, with some researchers going so far as to deny its existence (6).

Another thing to consider is that finasteride will affect sperm counts and other parameters of sperm quality, at least for the few first weeks or months. The extent to which these drops in sperm counts are significant enough to affect fertility is debated, but at any rate, if you are trying for a child it is a good idea to discontinue treatment, at least temporarily (7).

Having said that, there is no risk to the fetus from your taking finasteride. While finasteride per se is very harmful to fetuses, the amount of finasteride present in the semen (and which passes on to the women through sex) is miniscule, and certainly not enough to harm the unborn child. Finasteride tablets are coated for added protection, to further ensure the drug does not come into contact with a woman who is pregnant or trying to conceive. For that reason it is important to never crush the pill but swallow it whole.

One final point that will be very important to older men involves the drug’s interaction with PSA levels (8). Finasteride is known to drastically lower PSA levels, making the results of any test very difficult to interpret. If you are experiencing issues with your prostate and are taking finasteride it is something you should bring to the attention of your doctor.

Other Options to Consider

If you find finasteride does not work for you, there is no need to despair. Thankfully, there are many other treatment options out there, though many will not be as attractive as Propecia.

For starters minoxidil (brand name Rogaine) is an FDA-approved topical medication that gives almost as good results as Propecia (9). But the fact that you have to apply it on your scalp twice daily will make this an impractical solution for many men.

Other options to consider are natural 5-alpha-reductase inhibitors, most notably saw palmetto extract. Being a naturally occurring plant that can’t be patented, there is no incentive for a pharmaceutical company to seek FDA-approval for hair loss. But we have solid evidence that saw palmetto is about half to two thirds as effective as finasteride and with hardly any side effects, sexual or otherwise (10).

Other options to consider include Low Level Light Therapy (LLLT) which is a form of light therapy that stimulates hair growth and can be done at home via specialized helmets or caps (11). These have practically no side effects, though hair regrowth is modest compared to finasteride.

Finally, there are surgical options including Follicular Unit Extraction (FUE) and Follicular Unit Transplantation (FUT) (12). While these will give more dramatic and long-lasting results, they are proper surgical procedures and come with a hefty price tag.


Despite the fact that it’s pushing forty, finasteride remains the undisputed king of hair loss treatments. It will work to stop hair loss in the majority of users, meaning that if treatment is started early enough, a cosmetically acceptable head of hair can be maintained indefinitely. A famous example of this is Donald Trump himself, who has taken finasteride for many years and still sports full hair coverage well into his 70s. As such, it is definitely one of the first options to consider if you’ve just been diagnosed with hair loss.

Having said that, it is important to understand that regrowth will typically be modest and you are not actually “curing” your hair loss with finasteride, but merely masking the symptoms. These symptoms will then reappear when you discontinue treatment, at which point any hair you’ve regrown will fall back out, and your hair loss will resume its normal course. Your doctor will be able to give you more information on finasteride, including the potential side effects, as well as what can be done to avert or mitigate them if they appear.

If you want to learn more about finasteride, check out our comprehensive mega-guide on our YouTube channel: