Finasteride
A prescription DHT blocker that slows and can reverse male pattern baldness. Finasteride targets the hormonal root cause of hair loss — but you need to understand the side effect profile before starting.
Finasteride blocks the enzyme (5-alpha reductase) that converts testosterone to DHT — the hormone responsible for shrinking your hair follicles. At 1 mg/day, it reduces scalp DHT by about 60%, which is enough to stop hair loss and promote regrowth in most men.
Good for you if: You're a man experiencing androgenetic alopecia (thinning crown, receding hairline) and want to address the hormonal root cause, not just stimulate growth.
Dive deeper into the researchCommon side effects
- Reduced libido in 1–2% of users
- Erectile changes — rare and usually reversible on stopping
- Mood changes reported by some users
What does finasteride do?
Male pattern baldness is driven by DHT (dihydrotestosterone). Your body makes DHT from testosterone using an enzyme called 5-alpha reductase. Finasteride blocks this enzyme, reducing DHT levels by about 60–70% in the blood and scalp.
With less DHT hitting your follicles, miniaturisation slows down or stops. In many men, follicles that were shrinking start to recover, producing thicker hair again.
What can you expect?
- Reduced hair loss — most men notice less shedding within 3 months
- Maintained density — the biggest win is keeping what you have
- Regrowth — about 65% of men see measurable regrowth at 12 months
- Crown > hairline — works best at the crown, moderately at the hairline
How to use it
1 mg finasteride once daily — taken at the same time each day, with or without food. Results take 3–6 months to become visible.
For maximum results, combine with 5% minoxidil topical. Finasteride blocks the cause (DHT), minoxidil stimulates growth — they work through different mechanisms.
Topical finasteride: 0.25% topical finasteride is emerging as an option with potentially fewer systemic side effects. Available from some compounding pharmacies in India.
Important: Finasteride is for men only. Women of childbearing age should not handle crushed or broken tablets — finasteride can cause birth defects in male foetuses.
Track your DHT, testosterone, and hair health
eterni connects your hormone labs and treatments — so you can see if finasteride is doing its job.
Get early accessFrequently Asked Questions
Does finasteride cause permanent sexual side effects?
In clinical trials, 1–2% of men experienced decreased libido or erectile changes, and these resolved after stopping the medication in most cases. The concept of "post-finasteride syndrome" (persistent side effects after stopping) is debated — some case reports exist, but large studies have not confirmed it as a consistent phenomenon. Discuss risk tolerance with your doctor.
Can I take finasteride with minoxidil?
Yes, and this combination is considered the most effective medical approach for male pattern hair loss. Finasteride addresses the hormonal cause (DHT), while minoxidil stimulates blood flow and growth directly. They work through completely different pathways.
How long do I need to take finasteride?
Indefinitely, as long as you want to maintain results. If you stop, DHT levels return to normal within 2 weeks, and hair loss resumes. Most men who stop see reversal of gains within 6–12 months.
Does finasteride lower testosterone?
No — finasteride actually slightly increases total testosterone (by ~10–15%) because less testosterone is being converted to DHT. Free testosterone may also increase slightly. This is not clinically significant for most men.
How it works in your body
Finasteride selectively inhibits type II 5-alpha reductase, the enzyme predominantly found in hair follicles, prostate, and skin. By blocking this enzyme, it reduces DHT production by ~70% in serum and ~60% in the scalp. Testosterone levels increase slightly as less is converted to DHT.
Lower DHT at the follicle means less miniaturisation — follicles that were shrinking can recover and produce terminal (thick) hairs again.
What the studies show
- Hair count: 1 mg/day increased hair count by ~107 hairs per cm² at the vertex after 2 years vs placebo
- Prevention: 83% of men maintained or improved hair count at 2 years (vs 28% on placebo)
- Long-term: 5-year data shows sustained benefit, with 90% of finasteride users maintaining hair vs continued loss in controls
- Side effects: Sexual side effects in 1.8% vs 1.3% in placebo (small absolute difference)
Side effects & safety
The side effect profile is the main concern for most men considering finasteride:
- Decreased libido — Reported in ~1.8% of men in trials. Usually mild and often resolves with continued use.
- Erectile difficulty — Reported in ~1.3%. Reversible in most cases after stopping.
- Reduced ejaculate volume — Some men notice less semen volume. Not harmful.
- Mood changes — Depression and anxiety reported anecdotally, though controlled trials show minimal difference vs placebo.
- Breast tenderness — Rare (<1%). Resolves on discontinuation.
Important context: The nocebo effect is significant with finasteride — men who are told about sexual side effects before starting are more likely to report them. In blinded trials, the difference between drug and placebo is very small.
Which labs to check
Before starting and at 6–12 months:
- Total testosterone & free testosterone — expect a slight increase on finasteride
- DHT — should drop by ~60–70% (confirms it's working)
- PSA — finasteride halves PSA values; your doctor needs to know you're on it if they order this test
- Estradiol — rarely, the testosterone increase can lead to slightly higher estrogen conversion
Know what's working. Know what's not.
eterni connects your lab results, supplements, and retests — so you can see the trajectory, not just a snapshot.
Join the waitlist