Prescription drug Published: RCT evidence Extensive real-world use

Finasteride: dosing, timing and what to expect

5α-reductase inhibitor for hair loss (1 mg) and prostate (5 mg). Ubiquitous in the TRT-adjacent world, where it blunts the DHT that TRT raises.

Also known as Propecia, Proscar

Educational research reference Prescription Medications

Quick reference. Everything you need to run Finasteride — dosing, frequency, reconstitution math for the vial sizes people actually buy, and what it stacks with. For anything specific to your situation, ask the Guru.

Finasteride quick start

Route: Oral
Typical dose: 1 mg/day (hair); physician-set
Frequency: Daily
Half-life: ~6 hours, but tissue DHT suppression lasts days.
Cycle: Continuous.

These are the numbers people actually run, drawn from the published record and from what the community has settled on over time. Educational reference, not medical advice — a starting point to work from, and one you can adjust as you learn how you respond.

How to run it

How often: Daily
Cycle length: Continuous.
Half-life: ~6 hours, but tissue DHT suppression lasts days.
Route: Oral

Consistency matters more than perfect timing. Pick a slot in your day you will actually keep, and let DoseIQ handle the rest.

For women

Not used in women of reproductive age — it is teratogenic to a male fetus; pregnant women shouldn't even handle crushed tablets.

What to expect

Most people tolerate Finasteride well. Here is what is worth knowing going in, so nothing catches you by surprise.

Lowers PSA readings roughly by half — your prescriber interprets PSA accordingly, and so does the Markers page note. Sexual side effects are the community's permanent argument; report rather than ride them out.

Known interactions

Interactions involving Finasteride's drug class that DoseIQ screens for. Each one cites where it comes from — an FDA label section or the published record — because an interaction warning you can't trace is just noise.

Worth knowing Finasteride/dutasteride reshape TRT's DHT arm

They block conversion of testosterone to DHT — usually the deliberate point (hair), but it changes what a given T dose does.

What to do: Nothing to do if intentional; PSA readings run ~half their true value on these, which the Markers page notes.

Source: FDA labels, finasteride/dutasteride

DoseIQ screens your whole protocol against these rules automatically — every compound, prescription and supplement you track, cross-checked as you add them. Serious flags are always free.

Preparing it

Finasteride does not need reconstituting — it comes ready to use.

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This page is an educational research reference and is not medical advice. Dose figures reflect the published record and what the community has converged on — starting points to weigh, not instructions. Consult a qualified healthcare provider before starting any protocol.