Finasteride — the DHT blocker, with the side-effect conversation.

Finasteride is a 5α-reductase inhibitor. The enzyme it blocks (specifically the type II isoform) converts testosterone into dihydrotestosterone (DHT) — the androgen primarily responsible for both androgenic alopecia (male-pattern hair loss) and benign prostatic hyperplasia.

FDA-approved as Propecia (1mg, for hair) and Proscar (5mg, for prostate) since 1997. Generic since 2013. Best clinical evidence of any oral hair-loss drug, but the side-effect conversation is real and shouldn't be papered over.

DHT binds androgen receptors in hair follicles on the crown and hairline, triggering progressive follicular miniaturization — the hair shaft gets thinner with each cycle until the follicle is dormant. Finasteride reduces scalp DHT by about 60–70%, which slows or halts that miniaturization in the majority of patients and reverses it partially in some.

It doesn't regrow long-dormant follicles. The protocol's job is to preserve what's still active and reactivate recently-miniaturized follicles. Starting earlier produces better long-term outcomes than starting after major loss.

Finasteride tends to fit:

• Men with early-to-moderate androgenic alopecia who want to preserve density
• Patients comfortable with the side-effect conversation and willing to discontinue if effects appear
• Patients pairing it with low-dose oral minoxidil (the standard combination)

It does not fit men actively trying to conceive (DHT plays a role in spermatogenesis), and we have a different conversation with patients who have a history of depression or who've had post-finasteride concerns in prior trials.

Typical dosing for hair: 1mg oral, daily. Some patients respond to lower doses (0.5mg or 0.25mg every other day) with reduced side-effect risk; we titrate when the clinical case justifies it. Compounded 0.5mg capsules are available for this protocol.

Topical finasteride (compounded) is an alternative for patients who want to minimize systemic exposure. Smaller body of evidence but reasonable in carefully selected cases.

Hair changes lag the drug significantly. Shedding stabilizes around 3 months, density improvements visible at 6–12 months, peak response around 24 months. The first 3 months can feel like nothing's happening — that's expected.

Side-effect rates from FDA labeling: ~1–2% report sexual side effects (libido, ED, ejaculation). Most resolve on discontinuation. A smaller subset reports persistent symptoms after stopping — “post-finasteride syndrome” — and while the mechanism is debated, we take patient reports seriously and discontinue at any sign of concerning effects.

Generic 1mg or compounded 0.5mg through our pharmacy partner. Honest side-effect conversation on intake — we don't downplay the rates and we don't talk patients into staying on if effects appear. For patients pairing with minoxidil, the combined protocol is the better-evidenced approach than either alone.