Overview
Finasteride is tracked as a supplement in Milligram's compound library. Type II 5-alpha reductase inhibitor.
With a half-life of ~6 hours, Finasteride requires daily administration in most observed protocols. Taken orally, it has a bioavailability of approximately 65% via its primary route.
Plasma half-life approximately 6 hours, but enzyme inhibition persists beyond plasma clearance. Oral bioavailability approximately 65%. One-compartment model.
Mechanism of Action
Finasteride's pharmacological activity involves the following key pathways:
Primary Mechanism
Finasteride exerts its effects through its established pharmacological pathway. Its mechanism has been characterized in published research.
Enzyme Modulation
Finasteride modulates specific enzymatic pathways relevant to its pharmacological effects.
Dosing Protocols
The following protocols represent commonly observed dosing patterns. These are observational summaries, not recommendations.
Dose
1 mg/day
Route
Oral
Frequency
Once daily
Duration
Ongoing
Dose
2 mg/day
Route
Oral
Frequency
Once daily
Duration
Ongoing
Frequently Asked Questions
What is finasteride and how does it work for hair loss?
Finasteride is an oral 5-alpha reductase inhibitor that blocks the conversion of testosterone to dihydrotestosterone (DHT) – the primary androgen responsible for androgenetic alopecia (male-pattern hair loss). By reducing systemic DHT levels by approximately 65–70%, finasteride slows or halts hair follicle miniaturization at the crown and hairline in men genetically predisposed to pattern loss.
How long does finasteride take to show results for hair loss?
Most individuals begin to see stabilization of hair loss within 3–6 months of consistent daily use, with visible regrowth typically appearing between 6–12 months. The 2-year mark is generally considered the point of peak response. Finasteride primarily halts progression rather than fully reversing loss, though meaningful regrowth at the crown is reported in a significant proportion of long-term users.
What is the standard dose of finasteride?
The standard dose for androgenetic alopecia is 1 mg/day taken orally, which is the FDA-approved dose for this indication. Some protocols use 0.5 mg/day (half-tablet) as a lower entry point to reduce potential side effect exposure while still achieving meaningful DHT suppression. The higher 5 mg/day dose is approved for benign prostatic hyperplasia (BPH) and is not used for hair loss.
What are the potential side effects of finasteride?
Clinical trials report sexual side effects – including reduced libido, erectile dysfunction, and decreased ejaculatory volume – in approximately 2–4% of users, with the majority resolving upon discontinuation. A small subset of users report persistent symptoms after stopping (sometimes called post-finasteride syndrome), though the causality and prevalence remain debated. Mood-related effects including depression have also been reported and are listed on the label.
Can finasteride be used alongside testosterone or other androgens?
Finasteride is commonly used alongside testosterone replacement therapy (TRT) to mitigate accelerated hair loss that can occur when exogenous testosterone elevates DHT production via 5-alpha reductase. However, blocking DHT conversion also reduces some androgenic effects that may be desirable for body composition and libido. The interaction between finasteride and anabolic compounds varies by individual and the specific compounds used.
What happens if you stop taking finasteride?
DHT levels typically return to baseline within 1–2 weeks of stopping finasteride, and hair loss progression generally resumes within 6–12 months. Any regrowth achieved during treatment is often lost within 1 year of discontinuation. Because finasteride requires continuous use to maintain its effect, it is generally considered a long-term commitment rather than a short course.