Finasteride
Propecia · Proscar · MK-906 · Finpecia · Fincar
Last updated
At a glance
Overview
Finasteride can slow male pattern hair loss and improve hair counts in some men. It also has sexual, psychiatric and reproductive precautions that need to be discussed before treatment. The evidence concerns defined populations and formulations; it does not validate every online dosing schedule or steroid-cycle hair stack.
The dose tiers, protocol cards, modeled ratings and risk badges displayed on this page are not validated treatment plans or a complete list of prescribing contraindications. Use the actual product information and a clinician's assessment. The US Propecia label describes an oral prescription treatment for male pattern hair loss; topical products have different evidence and regulatory status.
New depression or suicidal thoughts while taking finasteride 1 mg require stopping it and contacting a healthcare professional promptly, under the May 2026 MHRA advice. Seek emergency help if there is immediate danger. Do not wait for a hair-growth review to discuss adverse effects. Editorial sources checked September 30, 2026.
How Finasteride works
DHT reduction is a mechanism, not a personal outcome#
Finasteride inhibits type II 5α-reductase, reducing conversion of testosterone to dihydrotestosterone (DHT). In a 42-day study of 249 men, several daily doses reduced scalp and serum DHT. That short biomarker experiment did not establish equivalent hair growth or safety for every lower-dose or alternate-day schedule.
It also did not study protection against hair loss during anabolic-steroid cycles. Do not infer a safe combination, a guaranteed level of protection or a reason to substitute a research antiandrogen from enzyme chemistry alone. A drug's plasma half-life is not a deadline by which an adverse symptom must resolve.
Protocol
| Level | Dose | Frequency | Notes |
|---|---|---|---|
| Low | 0.25–1 mg | Once daily | Documented entry-level range |
| Mid | 1–1.25 mg | Once daily | Most commonly studied range |
| High | 1–1.25 mg | Once daily | The US Propecia label specifies 1 mg orally once daily. Lower doses, alternate-day schedules, split 5 mg tablets and topical preparations are not interchangeable labeled regimens. The numerical tiers displayed here do not establish equivalent efficacy or individual suitability. |
Cycle length & outcomes
Documented cycle
52–520 weeks
Plateau after
78 wks
Review benefit and tolerability separately#
Finasteride is generally considered as ongoing treatment rather than a short cosmetic cycle. The original placebo-controlled trials evaluated outcomes over one and two years; the extension report found maintained benefit over five years among study participants. That does not promise regrowth for every person or make treatment an irrevocable lifetime commitment.
Agree on follow-up and comparable photographs with the prescriber. A shedding episode is not a validated test that treatment is working. New or worsening symptoms, sudden patchy loss or scalp disease merit assessment sooner than a scheduled cosmetic review. See when to review hair-treatment results.
Stopping can reverse treatment benefit; review the plan with the prescriber. Do not use a predicted DHT recovery time as reassurance about persistent symptoms.
Risks & mistakes
Sexual and psychiatric effects#
In the Propecia label's first-year trials, one or more of the specified drug-related sexual adverse experiences occurred in 3.8% of treated men versus 2.1% with placebo. These trial figures do not quantify the risk of symptoms persisting after discontinuation. The label includes postmarketing reports of persistent sexual dysfunction, depression, suicidal ideation/behavior, and male infertility or poor seminal quality; voluntary reports cannot establish their frequency. Prescribing information.
The MHRA's current advice distinguishes formulations: stop finasteride 1 mg and contact a healthcare professional promptly for depression or suicidal thoughts; for 5 mg finasteride, contact the healthcare professional as soon as possible. Sexual dysfunction also warrants medical advice. Discuss any history of depression or suicidal thoughts before starting. Immediate danger requires emergency assistance.
Do not manage new sexual or mood symptoms by adding tadalafil, an aromatase inhibitor or a research product, or by assuming a topical switch is risk-free.
Other warnings#
Report breast changes, testicular symptoms and fertility concerns. Seek urgent care for signs of a serious allergic reaction. Finasteride affects PSA results: tell the clinician ordering or interpreting the test, rather than applying a universal do-it-yourself multiplier. Its label also retains a high-grade prostate-cancer warning based on studies using the 5 mg dose in older men; that is not a measured cancer risk for a young person taking 1 mg.
The formal Propecia contraindications include pregnancy and hypersensitivity to product components. Site risk badges are broader screening categories, not substitutes for the complete label.
Stack & combine
Multipliers applied when these compounds run together. Values > 1 indicate a bonus on that axis. Tap a partner to expand the mechanism.
| Partner | Type | Lean | Fat loss | Recovery |
|---|---|---|---|---|
| synergistic | ×1.00 | ×1.00 | ×1.18 | |
| synergistic | ×1.00 | ×1.00 | ×1.15 | |
| synergistic | ×1.00 | ×1.00 | ×1.12 | |
| synergistic | ×1.07 | ×1.00 | ×1.08 | |
| synergistic | ×1.00 | ×1.00 | ×1.00 | |
| synergistic | ×1.00 | ×1.00 | ×1.00 | |
| synergistic | ×1.00 | ×1.00 | ×1.00 | |
| synergistic | ×1.00 | ×1.00 | ×1.00 | |
| synergistic | ×1.00 | ×1.00 | ×1.00 | |
| synergistic | ×1.00 | ×1.00 | ×1.00 | |
| synergistic | ×1.00 | ×1.00 | ×1.00 |
Pharmacokinetic conflicts, competing pathways, or compounded toxicity. Multipliers below 1 indicate the affected axis.
| Partner | Type | Lean | Fat loss | Recovery |
|---|---|---|---|---|
| antagonistic | ×1.00 | ×1.00 | ×1.00 |
FAQ — Finasteride
Research & citations
5 studies cited on this page.
Conclusion
Finasteride has controlled human evidence for male pattern hair loss. The useful decision is whether a specific product and follow-up plan fit the person's diagnosis, preferences and risks. Review benefit and adverse effects separately; do not substitute a dose tier, modeled graphic or untested combination for prescribing advice.