What Is Finasteride? A Simple Explanation

Finasteride is a prescription medication commonly used to treat male pattern hair loss (androgenetic alopecia). It works by targeting the hormonal process that causes hair follicles to shrink over time.

Unlike cosmetic products that focus on improving the appearance of hair, finasteride works at the root cause of pattern hair loss – helping to slow progression.

1. How Does Finasteride Work?

To understand finasteride, it helps to understand DHT.

What Is DHT?

DHT (dihydrotestosterone) is a hormone derived from testosterone and is the active form of testosterone. In men who are genetically predisposed, DHT binds to its relevant receptors in scalp hair follicles and gradually causes them to shrink.

This process is known as miniaturisation.

Over time:

• Hair growth cycle shortens

• Hair grows back thinner

• Density decreases

• Follicles may eventually stop producing hair

  
  

2. What Finasteride Does

Finasteride works by blocking the enzyme (5-alpha reductase type II) that converts testosterone into DHT.

By reducing DHT levels in the scalp:

• Follicle miniaturisation slows

• Further hair loss is reduced

• Existing hairs are preserved

• Regrowth may occur in responsive follicles

Finasteride does not eliminate DHT entirely – it lowers levels enough to protect hair follicles.

3. Who Is Finasteride Suitable For?

Finasteride is typically prescribed for:

• Men with male pattern hair loss

It is most effective when started early – before follicles have fully miniaturised.

Finasteride is not routinely prescribed to women of childbearing age and is only considered for postmenopausal women under specialist supervision in certain cases.

4. When Will I See Results?

Finasteride works gradually.

Typical timeline:

• Months 1–3: Hair loss stabilisation may begin

• Months 3–6: Reduced shedding

• Months 6–12: Visible thickening or regrowth in some individuals

• 12 months+: A more complete assessment of response

Finasteride is more effective at stopping further loss and allowing the follicle to recover and the hair to regrow.

5. Does Finasteride Regrow Hair?

In many men, yes, however, results vary. The primary goal of finasteride is to:

• Slow progression

• Preserve existing hair

• Maintain density

Combining finasteride with minoxidil often produces significant overall results.

Read more: What Is Minoxidil? A Simple Explanation

6. What Are the Possible Side Effects?

Finasteride is generally well tolerated, but like all prescription medications, it carries potential side effects, which can include;

• Reduced libido

• Erectile dysfunction

• Decreased ejaculation volume

These effects are uncommon and typically reversible upon discontinuation.

Large studies show the incidence of sexual side effects is low and many men take finasteride long-term without issue.

Other possible but rare side effects include:

• Breast tenderness

• Mood changes

  
  

7. How Are Side Effects Managed?

Side effects can often be mitigated by:

• Adjusting dosage

• Reducing frequency

• Switching to a topical formulation

Open communication with your prescriber is important. Most concerns can be managed quickly and safely.

8. What Happens If I Stop Finasteride?

Finasteride only works while you’re taking it.

If stopped:

• DHT levels return to previous levels

• Miniaturisation may resume

• Preserved hair may gradually be lost

This usually occurs over several months.

For chronic pattern hair loss, ongoing use is typically required to maintain results.

9. Can Finasteride Be Combined With Other Treatments?

Yes – and it often should be.

Finasteride:

• Blocks DHT

Minoxidil:

• Stimulates growth via different mechanisms, such as improving scalp circulation 

Together, they address different parts of the hair loss process.

10. Who Should Avoid Finasteride?

Finasteride is not suitable for indivuals who:

• Have certain hormone-sensitive conditions

• Experience sexual dysfunction

• Are actively trying to conceive, undergoing fertility treatment or have a known low sperm count

• Have a history of depression, anxiety or mental health concerns

A full medical consultation ensures safety and eligibility for treatment.

Final Thoughts

Finasteride is:

• A prescription-strength DHT-blocking treatment

• Clinically proven for male pattern hair loss

• Most effective at preserving existing hair

• Can be used alongside minoxidil

• Suitable for long-term use under medical supervision

It does not offer overnight results – but when started early and used consistently, it can significantly slow the progression of male pattern hair loss.

Understanding how finasteride works can help you determine whether it can form an effective part of your treatment plan.

References

1. Ong MM, Avram M, McMichael A, Tosti A, Lipner SR. Antiandrogen therapy for the treatment of female pattern hair loss: A clinical review of current and emerging therapies. J Am Acad Dermatol. 2025 Sep;93(3):749-760.

2. Gupta AK, Venkataraman M, Talukder M, Bamimore MA. Finasteride for hair loss: a review. J Dermatolog Treat. 2022 Jun;33(4):1938-1946.

3. Nestor MS, Ablon G, Gade A, Han H, Fischer DL. Treatment options for androgenetic alopecia: Efficacy, side effects, compliance, financial considerations, and ethics. J Cosmet Dermatol. 2021 Dec;20(12):3759-3781.