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Finasteride is a once-daily pill that lowers DHT, the hormone that shrinks hair follicles in male pattern baldness. At the standard dose of 1mg a day, it stops further loss in most men and regrows hair in about two-thirds over one to two years. It keeps working only while you take it.
Male pattern hair loss runs on a hormone called DHT, and finasteride is the one daily pill proven to bring it down. For a man watching his crown thin or his hairline creep back, it's the most studied oral option, and for most men it does two things at once: it stops the loss and brings some hair back.
Here's what the drug actually does inside a follicle, how well the trials say it works, the timeline you should expect, and an honest read on the side effects men ask about most.
How finasteride works
Finasteride is an oral 5-alpha-reductase inhibitor. The type II form of that enzyme converts testosterone into dihydrotestosterone (DHT), and DHT is what gradually shrinks scalp follicles in men with a genetic predisposition. Each affected hair grows back finer and shorter on every cycle until the follicle stops producing a hair you can see. Finasteride blocks the enzyme and cuts DHT in the scalp and bloodstream by roughly 60 to 70 percent. With less DHT in circulation, follicles stop miniaturizing, the loss slows, and many follicles that were on their way out start producing real hair again.
The reason it targets male pattern loss specifically is that this kind of balding is a DHT-driven, inherited sensitivity of the follicles on the top and front of the scalp. The follicles on the sides and back are largely immune, which is why men keep that ring of hair even when the crown goes. Lower the DHT and you take the pressure off the follicles that are vulnerable to it.
It's the same molecule as the 5mg tablet used for an enlarged prostate, just a lower dose. Finasteride 1mg taken once daily is the standard hair-loss dose, sold under the brand name Propecia. You can take it with or without food, at whatever time of day you'll actually remember. Consistency matters more than timing, so an occasional missed pill won't undo your progress, but skipping it for weeks will.
How well it actually works
The numbers come from large trials in men with male pattern hair loss. Over one to two years, roughly 80 to 90 percent of men stopped getting worse, and about two-thirds saw measurable regrowth. It does the most for the crown and the vertex at the back of the scalp, and it helps the temples too, though the hairline is usually the hardest zone to move.
For perspective, finasteride is the most effective oral treatment for male pattern hair loss that exists. No other pill matches its track record for slowing loss and producing regrowth. That's why it shows up as a first-line option in clinical guidance, usually alongside topical minoxidil rather than in competition with it.
The biggest factor in your result is when you start. Finasteride protects follicles that are still alive. It can't revive a scalp that's already gone smooth and shiny, because there's nothing left to rescue. Start while you still have miniaturized hair and the drug has the most to hold onto.
Finasteride protects the hair a man still has. The earlier he starts, the more there is to protect.
— John Venzor, DO
What to expect month by month
Patience is the hard part. Nothing dramatic happens in the first weeks, and the changes that matter show up slowly. The rough arc most men follow looks like this:
- Months 1 to 3: DHT drops fast, but the visible change is mostly that shedding eases off. Some men see a brief uptick in shedding first as follicles reset their growth cycle. That's expected and temporary.
- Months 6 to 12: regrowth becomes visible. Thicker coverage at the crown, fewer hairs in the drain.
- Months 12 to 24: peak benefit. What you see at the two-year mark is close to what the drug can do for you.
Then there's the catch worth understanding before you start. Finasteride holds its results only while you take it. Stop, and DHT rebounds within weeks. The hair you gained is usually lost over the next 6 to 12 months, and you drift back toward the path you would have been on without it. You stay on it to keep what it gives you.
Side effects in perspective
Most men take finasteride without any trouble. The side effects worth knowing about are sexual ones. In the trials, roughly 2 to 4 percent of men reported lower libido, trouble with erections, or changes in ejaculation. These are usually reversible: they tend to fade if you stop, and for some men they settle down even while continuing. Our guide to finasteride side effects walks through the evidence in more depth.
Two practical points round it out. Finasteride lowers PSA, the blood marker used to screen the prostate, by about half, so tell any clinician checking your prostate that you take it. Otherwise a normal-looking reading could hide a problem. You may also have read about "post-finasteride syndrome," a cluster of symptoms some men report persisting after they stop. It gets reported and actively debated, but it hasn't been established as a defined condition in the research. If side effects show up and bother you, that's a conversation to have with your clinician rather than a reason to quit on your own without a plan.
Finasteride is prescribed to men only. It can harm a developing male fetus, so women who are or may become pregnant should not take it, and should not handle crushed or broken tablets, since the drug can absorb through skin. Vyta.co's finasteride service is for men. A woman dealing with hair loss should talk with her own clinician about options that are safe for her.
Plenty of men pair finasteride with topical minoxidil, which works on the follicle a different way, for a bigger combined effect. If you're weighing one against the other, our finasteride vs. minoxidil comparison lays out where each one fits.