Finasteride – FolliQuest

Introduction

Sold under the brand names Propecia©, Proscar©, and others, finasteride is one of the most powerful hair loss medications currently available on the market.

With decades of research and usage, finasteride has proven to be safe and highly effective in stopping (and sometimes reversing) androgenic alopecia – the dreaded male pattern baldness.

Alongside minoxidil and ketoconazole shampoo, finasteride is part of the big 3 of hair loss prevention—the gold standard medication stack that is been used by millions of men worldwide to regain and maintain their hair.

Unfortunately, despite its low incidence of negative side effects and clinically proven safety, many people have started to be afraid of using finasteride—primarily due to the endless number of horror stories spread all over the internet.

This comprehensive guide will tell you everything you need to know about finasteride and its usage for combatting hair loss: What it is, how it works, what it can and cannot do, as well as its benefits and potential drawbacks.

📝 Table of Contents

History

Way back in the 1970s, it was discovered that men who suffered from a rare genetic mutation, that made them deficient in the 5α-R enzyme, had underdeveloped prostates and did not experience any hair loss during adulthood.

Following this discovery, research and experimentation had begun, in an attempt to develop a drug that can mimic this physiological state, that could perhaps be used for men with enlarged prostates.

After many years of trial and error, the medication was finally ready. Finasteride was patented in 1984 and was approved for medical use in 1992 for men suffering from benign prostate hyperplasia, at the high dose of 5 mg.

A few years later, in 1997, finasteride has also been approved for the treatment of male pattern baldness, at the lower dose of 1 mg daily tablets.

Ever since then, finasteride has been the gold standard treatment option for preventing and reversing hair loss, with many millions of men achieving success with this medicine.

Just in the United States alone, in 2020, finasteride was the 90th most prescribed medication, with over 8 million prescriptions.

How finasteride works

To fully understand how finasteride works we must first recap how the balding process is happening:

The hair is generated by tiny organs inside the scalp called hair follicles.
DHT is an androgenic hormone, which is created from testosterone, by an enzyme called 5α-Reductase.
Men suffering from pattern baldness have sensitive follicles that are susceptible to damage from DHT. This sensitivity to DHT is genetically determined.
Under the negative influence of DHT, the hair follicles shrink and become weaker over time—a process called follicle miniaturization.
As follicle miniaturization progresses over the years, the hair becomes shorter and thinner, and eventually stops growing altogether, causing baldness in that area.

So here is where finasteride comes into play:

The medication inhibits the production of the 5α-R enzyme, which in turn prevents testosterone from being converted into DHT. Taken at a dosage of 1 mg a day, this results in the lowering of DHT levels by about 70%.

By lowering scalp DHT, the damage stops, the miniaturization process stops, and the follicles are allowed to flourish.

This translates in the near-complete cessation of hair loss and the halting of the balding process. As the follicles regain their health, the hair becomes thicker and stronger, resulting in higher hair density on the scalp. Most men using finasteride are going to maintain their hair, and some may be able to see some regrowth—the reversal of male pattern baldness.

A common misconception about finasteride is that it is a DHT blocker. It is not. Finasteride is an enzymatic inhibitor. It blocks the 5α-R enzyme, which is required for converting testosterone into DHT. As a result of this blockade, less DHT is being produced, thus lowering the scalp and systemic levels of this hormone.

Finasteride expected results

Finasteride is extraordinarily effective at completely halting the follicle miniaturization process, and, by extension, stopping androgenic alopecia.

About 90% of users experience a complete cessation of hair loss within a year, and about half of them see hair regrowth and the reversal of their hair loss. The results from finasteride are going to peak at around the 2-year mark and can be maintained for many years—or even decades in some cases.

Early initiation of treatment increases the likelihood of seeing better results. Miniaturized hair follicles that are still at least 50% of their original size have a very good chance of reversing this process and rejuvenating to a healthy state.

The overall hair cosmetic improvement might be as high as 30%—which results from combining the newly increased hair count with the increased hair thickness.

And this is just by using finasteride by itself.

By pairing finasteride with other treatment modalities, such as minoxidil, the hair growth results can effectively double.

However, even if the potential results are very promising, hair follicles have lengthy growth cycles, which means that it might take at least 6 months (or more) to see any meaningful improvements.

This can be a problem since the unfortunate reality is that a lot of people who are suffering from hair loss are already undergoing massive emotional unrest, and the prolonged delay between starting finasteride and seeing the results can only add to their worries.

In addition to this, the sudden fluctuation in hormone levels that occurs when first starting finasteride might also temporarily increase hair shedding, which has scared many people into quitting finasteride even before it had a chance to start working.

When it comes to finasteride, patience and consistency are the name of the game. The results are going to happen, but finasteride is by no means going to be an overnight fix.

The optimal dose of finasteride

Just like most other pharmaceuticals, finasteride has something called a dose-response curve, which means that the body’s response to the medication will depend on the dosage—usually the higher the dosage, the greater the response. But there are some limitations:

Upper bound

Finasteride is being prescribed at high doses (5mg per day) for the treatment of enlarged prostate.

However, for the purposes of hair loss prevention/regrowth, multiple studies have confirmed that the dose-response curve of finasteride flattens abruptly at about 1mg/day.

This means that 1mg/day is the upper limit when using finasteride for hair loss prevention. Anything above this threshold is not going to result in better outcomes.

Exceeding this dosage is not only unnecessary but might also be harmful, since higher dosages might increase the risk of experiencing unwanted side effects.

Lower bound

The minimum dose of finasteride that has proven efficacy for combatting hair loss in clinical studies is 0.2mg per day.

Despite being 5 times lower than the usually prescribed 1mg dose, some studies have shown that near-maximum DHT suppression can be achieved with as little as a 0.2mg dose.

Although using such low dosages might not yield optimal hair growth results for all men, it’s important to keep in mind that finasteride can indeed be titrated down and still achieve a significant amount of reduction in DHT levels.

Finding the ideal dose

Every person has a unique physiology, and consequently, will have a different response to the same dose of medication. What works best for someone might be too much—or not enough—for a different person.

For this reason, there is no single cookie-cutter “optimal dose” that will work equally well for all people, instead, the dosage will need to be adjusted according to each individual’s needs.

The general strategy when approaching any medication is to opt for the minimum effective dose—a dose that is high enough to be an effective treatment, but low enough to prevent any unwanted side effects.

While some prescribing physicians will start off with the 1mg dose and titrate down if necessary, others will start with the conservative dose of 0.2 mg and increase it as needed.

A popular approach used by some prescribing physicians, is opting for the midground between the lower and upper bound, and using the dosage of 1mg, 3 times a week, which is the equivalent of about 0.4 mg of finasteride daily.

Finasteride timing and frequency

Finasteride’s half-life is about 8 hours, but its blocking effects on the 5α-Reductase enzyme can last up to 21 days, and the suppressed levels of scalp DHT can last for at least a month.

For this reason, unlike minoxidil, finasteride does not have to be taken on a daily basis and can be taken less frequently. This allows for greater flexibility when using a customized dose of finasteride.

For the sake of example, let’s consider the aforementioned 3 mg/week dosage:

Some people would prefer to take 1 mg pills three times a week, while others would rather split the tablets in half and take 0.5 mg daily, as part of their routine.

Since finasteride treatment is not too restrictive when it comes to dosage timing, the choice of taking it daily or a few times per week is mostly a matter of personal preference and is likely not going to affect hair outcomes.

Both approaches are going to work, but the key is to choose a protocol and routine that you can consistently adhere to in the long run.

Another benefit of finasteride’s relatively long serum and scalp DHT-suppressing time is that treatment can be interrupted for a few weeks without negatively impacting your hair.

Finasteride can be taken at any time during the day, with or without food.

Topical finasteride

Although finasteride has traditionally been prescribed orally, in tablet form, a recent trend in the hair loss prevention world has become increasingly popular:

The topical application of finasteride using a liquid solution – similar to minoxidil.

The philosophy behind using this approach is very simple: trying to get the full benefits of finasteride for the purposes of hair loss prevention, while minimizing systemic exposure and the risk of negative side effects.

This sounds very good in theory, and, fortunately, there is a growing body of scientific evidence to support the efficacy of topical finasteride, as well as the potential advantages it has over traditional oral medication.

Let’s examine topical finasteride’s pros and cons, and see how it compares to the traditional oral version of the medication – starting with the most relevant factors: efficacy and systemic exposure:

	Topical finasteride	Oral finasteride
Efficacy	✔	✔
Reduced systemic exposure	✔	❌
Cheaper price	❌	✔
Ease of use	❌	✔
Dosage accuracy	❌	✔

1. Efficacy in combatting hair loss

Before delving into the efficacy of topical finasteride, we must first understand the primary motivation for developing this localized application modality of the drug:

For the purposes of hair loss prevention, the blood level of DHT is actually completely irrelevant. What actually matters, is the scalp level of DHT, because that is where follicles are being affected by this hormone.

The blood DHT level is only useful as a proxy to quickly estimate the scalp DHT level without performing a biopsy—since there is a tight correlation between the two.

As such, it has been speculated that by applying finasteride topically, not only will the systemic absorption be lower, but it could actually be more effective—since the drug would be directly applied to the target area and preferentially inhibit the 5α-Reductase activity at the follicle level.

Fortunately, there have been multiple studies that have (at least in part) confirmed this theory, concluding that topical finasteride is nearly as effective—if not equally effective—as oral finasteride. Showing similar clinical benefits: increased hair count and thickness, with the near complete cessation of hair loss.

2. Systemic exposure and side effects

In spite of the fact that topical finasteride is only applied to the skin, research has shown conclusively that the medication’s effects do go systemic quite easily, and cause the suppression of blood levels of DHT—potentially to the same degree as the oral version of finasteride.

However, there is an important caveat to this, as it seems like the systemic absorption is highly dose-dependent:

It has been found that using lower doses of topical finasteride may have the potential to lower scalp DHT levels enough to see clinical hair growth improvements, while not affecting systemic DHT levels to the extent that the oral medication would.

One such example would be a recent study that has shown topical finasteride to be equally as effective as oral finasteride, despite having milder effects on the blood levels of DHT (34% reduction)—compared to the oral version (55% reduction).

Additionally, regardless of the finasteride dosage being used and the subsequent reduction in systemic DHT, it has been clearly established that the actual blood concentration of finasteride is 100 times lower when it is applied topically (compared to oral administration).

Not only there is a 100-fold reduction in systemic drug exposure, but when finasteride is applied topically, the compound is absorbed directly into the bloodstream through the scalp, skipping the GI tract and the first-pass liver metabolism.

Although larger and more in-depth studies are needed to clearly establish the safety profile of topical finasteride—and its potential advantages over the oral version—preliminary research and many anecdotal reports suggest that topical finasteride might be a good candidate for people who are either unable to tolerate or don’t want to use the medication orally.

3. Price

Topical finasteride is generally going to be more expensive than taking tablets. The price is going to vary based on the brand or compounding pharmacy.

The medication’s price should not be the main factor being accounted for when deciding on a treatment plan—since safety and efficacy should be the top concerns—however, since finasteride is going to be a long-term treatment, the monthly and yearly costs should also be taken into consideration.

4. Dosage accuracy

When it comes to the ability to accurately measure the dosage, oral finasteride is once again going to be the clear winner.

Topical finasteride comes in solution, gel, or spray form, and while most products offer clear instructions on how to measure the dosage, it’s very easy to accidentally apply more (or not enough) of the product onto your scalp.

When taking finasteride orally, even if the patient had been prescribed a custom dosage and he needs to break the tablets in half, the accuracy is going to be far superior—leaving very little room for error.

5. Ease of use

And finally, the ease of use: for the same reasons discussed previously, taking a pill is going to be significantly easier and less time-consuming than applying the medication topically.

How easy (or difficult) it is going to be to use topical finasteride depends on a few factors:

Product type—liquid, gel, or spray
Product quality—how quickly it dries out
Hair length—the shorter the hair, the easier to apply
Balding area size—a smaller area means less work

When NOT to take finasteride

There are certain scenarios where finasteride should be avoided to prevent harm. This is not an exhaustive list and you should thoroughly discuss with your doctor any concerns or potential counterindications that may apply to you specifically.

1. If your partner is pregnant

Women who are (or could) become pregnant should stay very far away from finasteride. The medication can cause serious harm to the fetus.

And this is not limited just to the ingestion of the drug – even getting in contact with a topical finasteride solution, or touching finasteride pills that have been crushed or broken carries the risk of exposure.

If your partner is currently pregnant or might become pregnant, it’s very important to take all the necessary safety precautions to avoid this dangerous exposure.

People who are using topical finasteride should consider switching to the oral version or even interrupting the treatment. Since the topical solution remains on the scalp long after it has been applied, it carries a substantial risk of exposure for your partner.

2. Conceiving a child

Finasteride has the potential to interfere with sperm quality and affect fertility.

If you are using finasteride, it’s very important to discuss with your doctor if you are planning to have a child. Your doctor will decide what are the appropriate actions to be taken before conceiving.

Most commonly, patients are instructed to interrupt the finasteride treatment for a few months, although the doctor might also recommend performing other medical tests or procedures based on your individual needs.

3. Young age

In healthy adult males, DHT remains an important hormone due to its powerful androgenic properties. However, clinical studies and decades of medical practice have shown that suppressing the production of this hormone (to some extent) is generally well tolerated and does not cause significant issues, in most cases.

However, during early development stages and puberty, DHT is critically important for the healthy development of the reproductive system and secondary male characteristics.

For this reason, finasteride should never be used by young men.

This medication is exclusively prescribed to adult men who are suffering from male pattern baldness, ideally after the age of 25, after undergoing a proper medical assessment and diagnosis.

4. Underlying health conditions

Although finasteride is well tolerated and regarded as safe in most cases, a proper medical evaluation needs to be performed by your doctor to determine if you have any underlying medical health conditions, before starting the treatment.

Part of this medical examination might be performing a comprehensive blood test on certain key markers that could indicate a disrupted hormonal profile or other health issues that could increase the likelihood of experiencing negative outcomes from taking finasteride.

Finasteride side effects

All medication, without exception, comes with the risk of experiencing negative side effects.

Finasteride is an FDA-approved treatment with decades of extensive research and millions of success stories in patients being treated for male pattern baldness. It is considered safe, effective, and well-tolerated by the majority of men.

Finasteride does have some potential side effects that may occur in a small minority of men. Some of those symptoms may include:

decreased libido
erectile dysfunction
gynecomastia (breast enlargement)
anxiety or depression

The incidence of these side effects is very low, but if you happen to experience any one of them, you need to discuss it with your doctor or healthcare provider.

The usual strategy for mitigating or eliminating side effects is titrating down the dose or cessation of medication.

Your doctor might also perform other medical tests before or after treatment, so it’s very important to be under medical supervision while taking finasteride.

Do you need to get blood tests before taking finasteride?

Your doctor may ask you to perform a number of medical tests, including bloodwork, before starting the treatment with finasteride.

Not all physicians are going to do this, and some might argue that it’s unnecessary and over the top, considering the fact that finasteride is generally safe and well tolerated by the vast majority of people taking it.

However, getting bloodwork done and having a comprehensive picture of what your health markers and hormonal profile look like before starting the finasteride is part of a solid strategy for preventing or mitigating any potential side effects that you might encounter later down the line.

If the medication proves to be ineffective for your hair loss, or you happen to experience any side effects, the initial blood tests can be used as a reference point to adjust your treatment accordingly.

In addition to that, since finasteride is going to interfere with the prostate-specific antigen levels (a blood marker that is used for diagnosing prostate issues), getting it checked before starting the medication might be a good idea.

And finally, even if everything goes perfectly well and you will never end up using the initial blood tests, checking your hormones, vitamins, and minerals levels is going to reveal any potential nutrient deficiency or underlying health condition that might have caused—or accelerated—your hair loss.

Some commonly recommended blood markers to be tested include:

Free and total testosterone
DHT (the hair’s enemy)
Estrogen
Prolactin
SHBG (sex hormone-binding globulin)
FSH (follicle-stimulating hormone)
PSA (prostate-specific antigen)
Thyroid and liver function tests

What happens if you stop taking finasteride?

Unfortunately, finasteride is not a (permanent) cure for hair loss. It is however very effective at stopping the condition, basically putting it on “pause”.

While you are regularly taking finasteride and inhibiting the production of DHT, your follicles will no longer be damaged by this hormone, and will therefore start to flourish – generating strong healthy hair and perhaps reversing some of the previous damage caused by miniaturization.

However, as soon as finasteride therapy is interrupted, the body’s production of DHT will gradually resume back to normal levels, and therefore the assault on the follicles will continue.

The good news is that getting off finasteride or forgetting to take a few doses here and there is not going to have immediate consequences for your hair.

Since finasteride starts working very slowly over the course of a few months, interrupting the treatment is also going to cause the hair loss to gradually resume in the following months – with all the gains being lost at around the 1-year mark after discontinuing the treatment.

Since the 5α-R enzymatic activity takes a few weeks to resume, and the scalp DHT levels are going to be suppressed for at least a month, most people can safely take a few weeks off finasteride without any issues.

Can you use finasteride along with minoxidil?

Finasteride can and is often used together with minoxidil in the treatment of male pattern hair loss.

The two medications are fundamentally different and have distinct mechanisms of action:

Finasteride inhibits DHT production and therefore protects the hair follicles from the harmful effects of this hormone.
Minoxidil does not have any anti-androgenic properties and therefore it cannot stop the miniaturizing process, but it is a very potent hair growth stimulant.

Both medications will result in hair growth, but only one of them is capable of stopping androgenic alopecia: finasteride.

Using minoxidil by itself as a monotherapy might result in some initial hair growth, but if the underlying hair loss condition is not properly addressed, the miniaturization will continue and the baldness will keep progressing over the years.

For this reason, the right strategy is to first use finasteride to halt the progression of hair loss and stabilize the condition, and only then add minoxidil into the protocol for maximizing hair growth.

Adding in the medications one by one, in this order, will not only ensure that you’re not losing any more ground, but it will enable you to assess the effectiveness of each treatment individually.

What about dutasteride?

Dutasteride is also a 5α-Reductase inhibitor and works similarly to finasteride. It is not FDA-approved for the treatment of male pattern baldness and, instead, it is primarily being used in severe cases of prostate enlargement.

Compared to finasteride, dutasteride is significantly stronger. It achieves near-complete suppression of systemic DHT levels and blocks all three 5α-Reductase isoenzymes:

	Finasteride	Dutasteride
5α-R Type 1	❌	✔
5α-R Type 2	✔	✔
5α-R Type 3	✔	✔
DHT Suppression	70%	95%

Dutasteride has shown to be superior to finasteride in terms of hair growth results, however, all this power does come with substantially increased risk:

Not only will dutasteride wipe out almost all the DHT in the system—which by itself could cause a number of issues—but it will also inhibit the type 1 isoenzyme of 5α-Reductase, which is highly active in the brain and is required for neurosteroid production.

Blocking this enzyme (type 1) is not only potentially harmful, but it also has no benefits for the purposes of hair loss prevention. The isoenzyme that is active in the scalp is 5α-R type 2, which finasteride does a great job at blocking.

Despite its increased risk for negative side effects, some physicians may still prescribe dutasteride off-label for the most severe cases of hair loss that are unresponsive to finasteride.

The vast majority of people are not going to need to go to such an extent, since finasteride—even at lower doses—is going to be more than enough to prevent and even reverse hair loss.

Conclusion

Finasteride is the gold-standard medication for the treatment of androgenic alopecia. It has decades of research and clinical use and was proven to be safe and effective.

Finasteride works by blocking the 5α-R enzyme, which results in the inhibition of systemic DHT levels by about 70%. This shields the hair follicles from damage and enables them to thrive—resulting in thicker and healthier hair, and the near complete stop of hair loss.

The potential results from using the medication are very promising, with a 30% increase in cosmetic appearance being commonly reported. However, this is not going to be an overnight transformation and it’s going to take several months to start seeing the results. Patience and consistency are key.

The medication is generally well tolerated and the incidence of side effects is very low. However, it’s important to discuss with your doctor any relevant concerns and report to them if you believe you are experiencing any side effects.

Finasteride allows a great degree of flexibility when it comes to dosage, frequency, and timing, enabling a prescribing physician to customize the treatment plan for each patient, according to their needs.

Continuation of the treatment is required to maintain the hair gained. If the treatment is interrupted, the hair loss will progressively resume over the course of a few months and all the progress will be lost after 1 year.

Finasteride can be used alongside minoxidil for maximizing the results since the two medications have different—and complementary—mechanisms of action: the former is a DHT inhibitor that mostly acts as a preventing agent, and the latter is the most potent hair growth stimulant on the market.

🔬Scientific References:

Steiner JF. Clinical pharmacokinetics and pharmacodynamics of finasteride. Clin Pharmacokinet. 1996;30(1):16-27. doi:10.2165/00003088-199630010-00002
Drake L, Hordinsky M, Fiedler V, et al. The effects of finasteride on scalp skin and serum androgen levels in men with androgenetic alopecia. J Am Acad Dermatol. 1999;41(4):550-554.
Roberts JL, Fiedler V, Imperato-McGinley J, et al. Clinical dose ranging studies with finasteride, a type 2 5alpha-reductase inhibitor, in men with male pattern hair loss. J Am Acad Dermatol. 1999;41(4):555-563.
Piraccini BM, Blume-Peytavi U, Scarci F, et al. Efficacy and safety of topical finasteride spray solution for male androgenetic alopecia: a phase III, randomized, controlled clinical trial [published correction appears in J Eur Acad Dermatol Venereol. 2023 Feb;37(2):452]. J Eur Acad Dermatol Venereol. 2022;36(2):286-294. doi:10.1111/jdv.17738
Hajheydari Z, Akbari J, Saeedi M, Shokoohi L. Comparing the therapeutic effects of finasteride gel and tablet in treatment of the androgenetic alopecia. Indian J Dermatol Venereol Leprol. 2009;75(1):47-51. doi:10.4103/0378-6323.45220
Caserini M, Radicioni M, Leuratti C, Annoni O, Palmieri R. A novel finasteride 0.25% topical solution for androgenetic alopecia: pharmacokinetics and effects on plasma androgen levels in healthy male volunteers. Int J Clin Pharmacol Ther. 2014;52(10):842-849. doi:10.5414/CP202119

⚠ Disclaimer: This article does not constitute medical advice and is intended for general informational purposes only. The information in the article is not a substitute for and should never be relied upon for professional medical advice, diagnosis, or treatment. Always discuss with your doctor if you have any questions. Please read our Medical Disclaimer.