Finasteride, the most effective drug against androgenetic alopecia


Introduction to Finasteride

Finasteride is a drug used for the treatment of:

    • Benign prostatic hypertrophy;
    • Prostate cancer;
    • Androgenetic alopecia (common baldness)

The drug is manufactured by the pharmaceutical company Merck. It has been on the US market since 1992 for the treatment of prostatic hypertrophy and since 1997 for the treatment of common baldness.

It has been available on the Italian market since 1997 for prostatic hypertrophy and in 1999 for androgenetic alopecia.

It is a very effective drug, unfortunately recently used in the world of sport to conceal the side effects of certain anabolic steroids for doping purposes.

The discovery of the molecule

It all began in 1974, when Julianne Imperato-McGinley, a New York-based researcher for Cornell Medical College, presented her research during a debate at a conference on birth defects. Her studies had focused on a group of hermaphrodite children living in a Caribbean community. These children had been raised by their families as females, as they had unclear features and very small male organs. During puberty, however, the male organs had developed and the features had changed considerably.

Studies showed that the genetic mutation in the children was due to a deficiency in the enzyme 5-alpha reductase and, consequently, in the androgenic hormone dihydrotestosterone (DHT). This led to an abnormal development of the reproductive system. In addition, it was observed that the prostate of these boys was very small after development.

This detail led to the insight of the head of research at the Pharmaceutical company Merck, who realised that it would be possible to synthesise an inhibitor of the 5-alpha reductase enzyme to reduce the size of the prostate in patients with benign prostatic hyperplasia.

What is Finasteride?

Finasteride is a synthetic 4-azasteroid compound and is the progenitor of all those specific inhibitors of the enzyme responsible for baldness and benign prostatic hyperplasia.

It appears as a white crystalline substance, soluble in chloroform and insoluble in water.

Finasteride and hair loss

Finasteride is one of the drugs most commonly prescribed by trichologists for the treatment of hair loss. As you can read here (link to other page), androgenetic alopecia, or common baldness, is caused by the action of androgenic harmonics on the hair follicles of the scalp.

In particular, dihydrotestosterone (DHT), a hormone developed by the synthesis of testosterone by a particular enzyme, 5-alpha reductase type 2, is responsible for the miniaturisation process of hair follicles. The hair becomes thinner and thinner, loses its characteristic colour and does not grow back after falling out.

Finasteride counteracts thinning hair by acting on the synthesis of dihydrotestosterone in the tissues, selectively inhibiting the enzyme 5-alpha reductase type 2.

Finasteride is therefore prescribed with the aim of decreasing DHT levels, preventing follicle miniaturisation and, in some cases, promoting new hair growth.

One of the positive aspects of Finasteride is that it is able to inhibit the action of the 5-alpha reductase enzyme without impeding the physiological action of testosterone, a key hormone for men in particular.

Dose and method of ingestion

In order to be effective against hair loss, Finasteride must be taken systemically, i.e. orally. This is why Finasteride is available on the market in the form of tablets to be ingested by mouth.

It should be noted that Finasteride appears on the market under the registered trademarks of Proscar, with a concentration of 5 mg, and Propecia, 1 mg. The doses recommended by experts for male patients for the treatment of androgenetic baldness are precisely 1 mg per day.

Maximum concentrations are reached in about 2 hours while absorption ends after 8 hours.

Does Finasteride work?

Several studies have shown Finasteride to be effective in treating baldness. After about a year of intake, about 50% of male patients between 18 and 41 years of age notice a decrease in hair loss, while the remaining half also notice growth. In less than 1% of cases, the drug proved ineffective.

One of the reasons Finasteride is so effective is the way it is taken. Another recommended anti-baldness drug, Minoxidil, cannot be administered systematically.

After taking the tablet orally, Finasteride is immediately absorbed from the gastrointestinal tract. Already after 24 hours, there is a 65% reduction in the concentration of DHT. However, in order for the benefits of the drug to be seen, treatment must be continued for at least three months. Experts generally recommend treatment for at least 12 months so that the effects can be better assessed. In addition, it should be noted that the benefits of Finasteride only last as long as the drug is taken, and stop after therapy is discontinued.

A more complex issue concerns women, for whom Finasteride seems to be less effective, especially in the menopausal period, when hair loss is mostly linked to oestrogen. Women of childbearing age, however, cannot take the drug because of the risk of pseudohermaphroditism in the foetus due to the overly aggressive action of the hormones.

Side effects of Finasteride

Generally Finasteride is a drug that is easily tolerated by the human body. However, as already mentioned, it is necessary that the treatment is prolonged, i.e. lasts for at least three months, for it to have the desired effects against hair loss. In many cases, the drug has to be taken for a year or more for it to be effective.

Such administration frightens patients, given the information circulating on the web about the sexual side effects of Finasteride.

In fact, side effects are often absent or, if present, reduced. About 3-4% of patients complain of some of the following:

  • Libido drop: psychological ability to respond to stimuli in the sexual and physical spheres. It is a drive, a desire that drives the sexual act and makes it pleasurable. Without this drive, the sexual act is purely mechanical. Libido must not be confused with potency, i.e. the purely physical capacity to perform the sexual act. Of course, it should be emphasised that, very often, the psychological dimension and the physical act go hand in hand.
  • Erectile dysfunction: inability to have an erection or to maintain it, despite the presence of sexual desire on a psychological level
  • Decrease in ejaculate volume: decrease in the amount of seminal fluid produced
  • Unilateral gynecomastia: increase in the volume of one of the male breasts
  • Alterations in spermatogenesis (only if correlated with varicocele or obesity): process leading to the maturation of male germ cells within the testicles by hormonal action
  • Testicular and penile numbness: decrease in sensitivity.
  • Withdrawal: indolence in fulfilling daily needs.

Some articles report a correlation between Finasteride and prostate cancer, but there are no studies proving such a link.

However, side effects of Finasteride intake are transient and disappear immediately after discontinuation of therapy.

Post-Finasteride Syndrome. Does it really exist?

About 5 years ago, the American forum “Propecia Help” introduced for the first time a term still used, not only on the web, by users and potential users of Finasteride: Post-Finasteride Syndrome.

This term refers to one of the biggest fears of those who are about to start a drug therapy aimed at stopping hair loss caused by androgenetic alopecia.

This term refers to a neurological and psychiatric condition that occurs as a result of reduced libido and erectile dysfunction caused by taking Finasteride.

Indeed, as we have indicated, there are several studies showing that a small percentage of users complain of side effects in the sexual sphere. Cases of decreased libido, erectile dysfunction and decreased ejaculatory volume occurred in 3.8% of cases one year after starting therapy and were reduced to 0.3% after five years. However, it has been proven that as soon as the drug is discontinued, these undesirable phenomena also disappear.

Side effects of this kind undoubtedly have a profound effect on the psychological dimension of the individual. A drop in self-esteem, fear of permanent damage, discomfort and inadequacy, and anxiety are just some of the unpleasant conditions caused by sexual dysfunction. For a young man, all this can be a difficult trauma to overcome, which may persist even after therapy has stopped.

However, in spite of the great public interest in the subject, there are still no studies that prove the concrete existence of the post-Finasteride syndrome.


    • The drug is only effective in males
    • Pregnant women should avoid touching the tablets as the active ingredients can be absorbed through the skin. Finasteride may cause malformation of the external genitalia of the fetus.
    • Pregnant women should avoid touching the tablets as the active ingredients may be absorbed through the skin.
    • Since Finasteride is metabolized by the liver, before starting therapy, make sure that the patient is not suffering from liver failure.
    • No specific studies have been conducted regarding long-term human fertility and possible impairment of fertility.

Finasteride for women

As indicated above, Finasteride is only approved for use by men. Nevertheless, there are several off-label uses.

Finasteride has been shown to be effective in women for the treatment of androgenetic alopecia and hirsutism (abnormal hair growth in women in areas of the body where hair is not usually present).

Researchers, however, recommend that the instructions on the package leaflet be strictly adhered to. Years of research are needed before the drug can be taken by women without health risks.


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