What is the use of Finasteride (Propecia)?

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Last updated: March 4, 2025 • View editorial policy

From the Guidelines

Finasteride is a medication primarily used to treat male pattern baldness and enlarged prostate (benign prostatic hyperplasia), with a recommended dose of 1mg daily for hair loss and 5mg daily for prostate issues.

Key Points

  • Finasteride works by inhibiting the enzyme 5-alpha-reductase, which converts testosterone to dihydrotestosterone (DHT), a hormone that contributes to hair loss and prostate enlargement 1.
  • By reducing DHT levels, finasteride can slow or stop hair loss and even promote some regrowth in many men, while also reducing prostate size and improving urinary symptoms 1.
  • Side effects may include decreased libido, erectile dysfunction, and decreased ejaculate volume in a small percentage of users, which are typically reversible upon discontinuation 2, 3.
  • Women who are pregnant or may become pregnant should not handle crushed tablets due to potential risks to male fetuses 4.
  • Results for hair loss typically take 3-6 months to become noticeable, and the medication must be taken continuously for benefits to persist 5.
  • Regular follow-up with a healthcare provider is recommended to monitor for effectiveness and any adverse effects 6.

Considerations

  • The use of finasteride for prostate cancer chemoprevention is still a topic of debate, with some studies suggesting a potential increase in high-grade cancers 7, 6.
  • However, the majority of evidence suggests that finasteride is safe and effective for the treatment of benign prostatic hyperplasia and male pattern baldness 1, 5.
  • Patients should be fully informed of the potential benefits and risks of finasteride, including the possibility of increased high-grade cancers, and should be closely monitored by a healthcare provider 6.

From the FDA Drug Label

The development and enlargement of the prostate gland is dependent on the potent androgen, 5α -dihydrotestosterone (DHT). Finasteride is a competitive and specific inhibitor of Type II 5α-reductase with which it slowly forms a stable enzyme complex.

The use of Finasteride (Propecia) is to inhibit the production of DHT (dihydrotestosterone) by blocking the enzyme Type II 5α-reductase, which is involved in the development and enlargement of the prostate gland.

  • The main effect of Finasteride is to reduce the levels of DHT in the body, which can help to treat conditions such as Benign Prostatic Hyperplasia (BPH). 8

From the Research

Uses of Finasteride

  • Finasteride is used to treat benign prostatic hyperplasia (BPH) by reducing prostate size and improving urinary flow rate and urological symptoms 9
  • It is also used to treat male pattern hair loss (androgenetic alopecia) by inhibiting the conversion of testosterone to dihydrotestosterone (DHT), which is implicated in hair loss 10, 11, 12
  • Finasteride has been shown to promote hair growth and prevent further hair loss in a significant proportion of men with male pattern hair loss 10, 11, 12
  • It can also be used to treat haematuria (blood in the urine) caused by BPH, and has been shown to be effective in preventing new bleeding 13

Mechanism of Action

  • Finasteride works by inhibiting the enzyme 5 alpha-reductase, which converts testosterone to DHT 9, 10, 11, 12, 13
  • By reducing DHT levels, finasteride decreases the size of the prostate gland and promotes hair growth 9, 10, 11, 12, 13

Side Effects

  • Common side effects of finasteride include decreased libido, ejaculation disorders, and impotence 9, 10, 12, 13
  • Other side effects may include gynaecomastia (breast tenderness or enlargement) and decreased ejaculate volume 10, 13

References

Research

Finasteride in the treatment of alopecia.

Expert opinion on pharmacotherapy, 2004

Research

Use of finasteride in the treatment of men with androgenetic alopecia (male pattern hair loss).

The journal of investigative dermatology. Symposium proceedings, 2003

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.