Yes, Is Finasteride a Drug? A Comprehensive Pharmacological Overview

October 6, 2025 •

4 min read

First approved by the U.S. Food and Drug Administration (FDA) in 1992, finasteride is an established prescription drug used to treat male-related health conditions. This article explores the pharmacological details to definitively answer: Is finasteride a drug?, and explains its mechanism, uses, and potential risks.

Quick Summary

Finasteride is a prescription medication and a 5-alpha reductase inhibitor used to treat male pattern hair loss and benign prostatic hyperplasia. It functions by inhibiting the conversion of testosterone to DHT, a hormone that contributes to both conditions.

Key Points

Prescription Status: Finasteride is a prescription-only drug, not an over-the-counter product or supplement.
Drug Class: It is a 5-alpha reductase inhibitor, which prevents the conversion of testosterone to dihydrotestosterone (DHT).
Dual Purpose: The medication is approved to treat two conditions in men: benign prostatic hyperplasia (BPH) and male pattern hair loss.
Appropriate amount Differences: The appropriate amount varies depending on the condition being treated.
Side Effect Profile: Common side effects include sexual dysfunction and mood changes, which should be discussed with a doctor.
Pregnancy Warning: Finasteride is contraindicated for women who are pregnant or may become pregnant due to the risk of harm to a male fetus.
Long-term Commitment: The medication must be taken consistently for several months to achieve and maintain its effects for both BPH and hair loss.

What is Finasteride?

Finasteride is the generic name for a medication classified as a 5-alpha reductase inhibitor. It is available in various strengths and is sold under brand names such as Propecia and Proscar, among others. A prescription from a healthcare provider is required to obtain finasteride. Its chemical structure is a synthetic steroid, which allows it to interact with specific enzymes in the body to produce its therapeutic effects.

Unlike an over-the-counter supplement or herbal remedy, a drug like finasteride undergoes rigorous testing and approval processes to ensure its safety and efficacy for specific medical conditions. Its status as a drug means it must be taken exactly as prescribed by a doctor, with careful consideration of its potential benefits and side effects.

How Does Finasteride Work?

Finasteride's primary mechanism of action involves inhibiting the enzyme 5-alpha reductase. This enzyme is responsible for converting the male hormone testosterone into a more potent form called dihydrotestosterone (DHT). By blocking this conversion, finasteride effectively lowers DHT levels in targeted areas of the body, such as the scalp and prostate.

There are two isoenzymes of 5-alpha reductase, Type I and Type II. Finasteride selectively inhibits the Type II isoenzyme, which is predominantly found in the scalp, prostate, and liver. By reducing DHT, finasteride helps address conditions where high DHT levels are a contributing factor.

What Conditions Does Finasteride Treat?

Finasteride is prescribed for two distinct medical conditions in men, with the appropriate amount differing for each.

Benign Prostatic Hyperplasia (BPH)

For men with an enlarged prostate gland, or BPH, finasteride is prescribed. BPH symptoms, such as frequent or difficult urination and incomplete bladder emptying, are caused by an enlarged prostate that presses on the urethra. By lowering DHT levels, finasteride helps to shrink the prostate over time, alleviating these bothersome urinary symptoms. Patients taking finasteride for BPH should be aware that it may take six months or more to experience the full benefits.

Male Pattern Hair Loss

For men experiencing male pattern hair loss, or androgenetic alopecia, finasteride is prescribed. In this condition, hair follicles in the scalp are sensitive to the effects of DHT, which causes them to shrink and produce thinner, shorter hair until they stop growing entirely. By blocking DHT, finasteride slows or stops hair loss and, for many men, promotes new hair regrowth. Like BPH treatment, results for hair loss are gradual and require consistent, long-term use to maintain.

Can Finasteride Be Used in Women?

While primarily used in men, finasteride is sometimes used off-label by specialists to treat certain types of hair loss or excess hair growth (hirsutism) in postmenopausal women. However, it is contraindicated for women who are or may become pregnant due to the risk of birth defects in male fetuses.

Common Side Effects and Risks

As with any potent medication, finasteride is associated with potential side effects and risks. It is crucial for patients to discuss these with their doctor before beginning treatment.

Key side effects can include:

Sexual Dysfunction: The most commonly reported side effects are sexual in nature, including decreased libido, erectile dysfunction, and ejaculatory problems. These symptoms often subside after discontinuing the medication, but in some cases, can persist, a condition referred to as Post-Finasteride Syndrome (PFS).
Psychological Effects: Mood changes, including depression and anxiety, have been reported in some men taking finasteride.
Breast Changes: Gynecomastia (enlarged breasts) and breast tenderness are rare side effects that have been reported.
Prostate Cancer Risk: Finasteride can affect prostate-specific antigen (PSA) levels, a marker used to screen for prostate cancer. Studies have also shown a slight increase in the risk of high-grade prostate cancer in some men taking the drug.

Finasteride vs. Dutasteride Comparison

Both finasteride and dutasteride are 5-alpha reductase inhibitors used to treat similar conditions, but they differ in their mechanism and effects.


Feature	Finasteride	Dutasteride (Avodart)
Drug Class	5-Alpha Reductase Inhibitor	5-Alpha Reductase Inhibitor
Enzyme Inhibition	Selectively inhibits Type II 5-alpha reductase.	Inhibits all three types (Type I, II, and III) of 5-alpha reductase.
DHT Reduction	Reduces serum DHT levels by about 70%.	Reduces serum DHT levels by more than 99%.
Primary Uses	BPH and male pattern hair loss.	BPH. Can be used off-label for hair loss.
Mechanism	More specific inhibition of the Type II enzyme.	Broader and more potent inhibition across all three enzyme types.

Conclusion

In conclusion, there is no doubt that is finasteride a drug, a conclusion reinforced by its classification as a prescription medication that requires medical supervision for use. As a potent 5-alpha reductase inhibitor, it offers a proven therapeutic pathway for men dealing with benign prostatic hyperplasia and male pattern hair loss by addressing the underlying hormonal imbalances. While highly effective, patients must be fully informed of the potential side effects and risks, including sexual and psychological issues. The decision to use finasteride should be made in consultation with a healthcare professional after a thorough evaluation of its benefits and risks relative to individual health circumstances.

For more detailed, clinical information on finasteride, patients can refer to trusted medical resources such as the U.S. National Library of Medicine.

Frequently Asked Questions

Yes, finasteride is a synthetic steroid molecule. However, it is not an anabolic steroid and does not act like one. Instead, it works by inhibiting the enzyme 5-alpha reductase, which affects hormone conversion, rather than directly building muscle mass.

No, finasteride is a prescription-only medication and cannot be obtained over-the-counter. It is important to consult a healthcare provider to determine if finasteride is a safe and appropriate treatment option for you.

Both Propecia and Proscar contain the same active ingredient, finasteride, but are different preparations prescribed for different conditions. Propecia is for male pattern hair loss, while Proscar is for benign prostatic hyperplasia (BPH).

Results with finasteride for male pattern hair loss are gradual. It may take at least three to six months to notice any improvement, with full effects often seen after 12 months or more of consistent daily use.

If you stop taking finasteride, the therapeutic effects will reverse. For hair loss, you will likely lose any hair that was gained within a year. For BPH, the prostate may begin to enlarge again after a few months.

Finasteride is not known to have many significant drug-drug interactions and does not affect the cytochrome P-450 enzyme system. However, patients should always inform their doctor of all medications and supplements they are taking, particularly supplements like saw palmetto, which has a similar mechanism of action.

Finasteride is generally not prescribed for women, and it is strictly contraindicated in pregnant women or those who may become pregnant. Exposure, even through skin contact with a crushed or broken tablet, can cause birth defects in male fetuses.

No, finasteride does not cure hair loss or BPH. It controls these conditions and the therapeutic effects last only as long as the medication is taken. Continued, consistent use is necessary to maintain results.