Oral finasteride 1 mg is an FDA-approved, proven treatment for male androgenetic alopecia. It targets the root driver of the condition: by inhibiting type II 5-alpha-reductase (5AR), the enzyme that converts testosterone into DHT, it lowers DHT in the scalp and bloodstream. Because it can slow or partly reverse the follicular miniaturization that causes thinning, it works on the cause itself and is often paired with minoxidil, which works by a complementary mechanism.
As with other proven treatments, the effect builds gradually over 4 to 12 months, and results are maintained only with continued use — stopping reverses the benefit. A minority of men report sexual side effects such as reduced libido or changes in erectile or ejaculatory function. "Post-finasteride syndrome," in which symptoms are said to persist after stopping, is reported but remains debated and unproven; an honest view neither asserts it as established nor dismisses it outright.
Pregnancy warning: finasteride is teratogenic and can harm a developing male fetus, so women who are or may become pregnant must not even handle crushed or broken tablets. The drug also lowers PSA, a prostate-cancer screening marker, so always tell any clinician you are taking it before PSA testing or a prostate evaluation.
Sources: StatPearls (NIH) ↗
FAQ
I'm worried about sexual side effects — how common are they?
Reduced libido and changes in erectile or ejaculatory function are reported in a minority of men, not the majority, and often resolve after stopping. "Post-finasteride syndrome," where symptoms persist after discontinuation, is reported but its cause-and-effect link is still debated. If side effects concern you or appear, discuss them with a clinician rather than deciding on your own.
Can women take finasteride?
Finasteride is FDA-approved only for men, and crucially, women who are or may become pregnant must not take it or even handle broken tablets because of the risk of harm to a male fetus. There are other proven options for female pattern hair loss, so see a dermatologist for an individualized plan.
Will it affect my prostate (PSA) test?
Yes — finasteride lowers PSA levels, which can affect how the result is interpreted. Always tell your doctor you are taking it before a PSA test or prostate evaluation so the result can be assessed accurately.
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⚠️ When to see a doctor — don’t self-treat
- Sudden patchy or circular bald spots
- Redness, scaling, pus, pain or itch (possible scarring alopecia — treat urgently)
- Broken hairs or rapid loss
- Loss with body-wide signs (weight loss, fatigue, cycle changes, acne, extra hair)
- Loss right after a new medication
- Any hair loss in a child