Finasteride

How Does Finasteride Work?

In men with hereditary hair loss, the hormone DHT plays a central role. It attaches to receptors in hair roots and triggers a gradual shrinking process. Finasteride targets this mechanism directly: it blocks the enzyme 5-alpha-reductase (type II), which is responsible for converting testosterone to DHT. ^[1]

DHT binds to androgen receptors approximately ten times more strongly than testosterone and is the main cause of hair follicle miniaturization. By reducing DHT levels by approximately 70%, finasteride slows miniaturization and allows shrunken follicles to produce stronger hairs again. ^[2]

In addition to DHT reduction, finasteride also influences cellular processes in the hair follicle. It reduces the activity of pro-apoptotic enzymes (caspases) involved in cell death while increasing protective proteins such as XIAP and Bcl-2. These effects help preserve hair follicles and extend the growth phase (anagen).

Efficacy

The efficacy of finasteride is well documented through extensive clinical studies. In a large study of over 1,500 men, 48% of the finasteride group showed improvement after 12 months, compared to only 7% in the placebo group. ^[1] Hair counts increased or stabilized in the treatment group, while the placebo group continued to lose hair.

Long-term studies over 5 years confirm that most patients can maintain or further improve their hair density. ^[2] Effects typically begin after 3-6 months and reach their maximum after about 2 years of continuous use. For optimal results, finasteride can be combined with minoxidil, as both active ingredients work through different mechanisms.

Interestingly, studies show that lower dosages can also be effective. A 48-week study found that 54% of men on 0.2 mg daily showed improvement, compared to 58% on 1 mg. ^[5] This suggests that for some individuals, a lower dose could be an alternative to minimize potential side effects.

Oral Versus Topical Application

Oral finasteride at the standard dose of 1 mg daily reduces blood DHT levels by approximately 70% and scalp DHT by 62-72%. ^[3] This systemic effect is very effective but may cause side effects in some individuals.

Topical finasteride offers an alternative with potentially lower systemic absorption. Studies show that topical formulations with approximately 0.1-0.9 mg daily exposure can reduce scalp DHT levels by 68-75%, comparable to the oral form. At the same time, systemic absorption is significantly lower, potentially reducing the risk of side effects. ^[3]

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Safety and Side Effects

Finasteride is generally well tolerated. The original approval studies showed sexual side effects in 1.8% of men on finasteride, compared to 1.3% on placebo. ^[1] This means only about 0.5% of users are actually affected due to the medication.

The most commonly reported side effects include decreased libido, erectile dysfunction, and ejaculatory disorders. According to study data, these effects are reversible: when the medication is discontinued, values typically normalize within 2-3 months. It is also noteworthy that many men who experience side effects in the first 2-3 months report spontaneous improvement with continued treatment.

Regarding long-term safety, studies involving over 30,000 men with 18 years of follow-up show that finasteride can reduce the risk of prostate cancer by approximately 25%. ^[4] Contrary to earlier concerns, finasteride does not increase the risk of high-grade prostate cancer, but rather facilitates its detection through prostate shrinkage.

Application

The standard dosage is 1 mg once daily, regardless of meals. The tablet should be swallowed whole and not split, as the active ingredient can be absorbed through skin contact. For individuals concerned about side effects, a lower dose (0.2-0.5 mg) may be considered under medical supervision.

Treatment requires patience: first visible results typically appear after 3-6 months, with maximum effects only after 1-2 years. After discontinuation, hair loss returns within 3-12 months, as finasteride controls the genetic predisposition but does not eliminate it.