Minoxidil vs Finasteride: Which Hair Loss Drug on TRT?

Minoxidil and finasteride are the two drugs with the strongest evidence for male pattern hair loss, and they are often confused as alternatives. They are closer to partners.

Finasteride is a type II 5-alpha reductase inhibitor. At 1 mg a day it lowers scalp DHT by about 64% and serum DHT by about 71% (Drake 1999, PMID 10495374). It treats the cause of pattern hair loss in men whose androgen is testosterone.

Minoxidil is a potassium channel opening vasodilator. Its active form, minoxidil sulphate, shortens the resting phase of the hair cycle without touching androgens (Messenger 2004, PMID 14996087). It comes as a topical solution or foam, as off-label low-dose oral tablets, and as VDPHL01, an extended-release tablet in Phase 3 trials.

For men on TRT or a cycle, the comparison matters because finasteride only works on androgens that need 5-alpha reductase, while minoxidil works whatever the androgen.

Mechanism:

• Finasteride: removes the DHT signal at the follicle. Slows or stops miniaturisation.
• Minoxidil: stimulates the follicle directly. Regrows and thickens, independent of DHT.

Which androgens it covers:

• Finasteride: only DHT made from testosterone. It cannot reduce the effect of DHT-derived steroids such as masteron, primobolan, anavar or winstrol, and may make nandrolone more androgenic at the scalp by blocking its conversion to the weaker DHN.
• Minoxidil: works regardless of which androgen is driving the loss.

Size of effect (different trials, not head to head):

• Finasteride 1 mg: 107 more hairs than placebo in a 5.1 cm² vertex area at one year, 138 at two years (Kaufman 1998, PMID 9777765). Roughly 21 hairs/cm².
• Oral minoxidil (VDPHL01 8.5 mg once daily): 22.0 hairs/cm² over placebo at six months in Study 304, company-reported.
• Oral 5 mg vs topical 5% minoxidil: no significant difference in hair density over 24 weeks (Penha 2024, PMID 38598226).

Side effects:

• Finasteride: erectile dysfunction risk roughly doubled versus placebo, number needed to harm about 82 (Mella 2010, PMID 20956649). Halves PSA.
• Oral minoxidil: unwanted body hair (49% at 5 mg in Penha 2024), a few bpm higher resting heart rate, ankle or eyelid swelling in a minority. Topical minoxidil: scalp irritation, rarely systemic effects.

Effect on bloodwork:

• Finasteride: DHT down, PSA down by about half, testosterone and oestradiol may drift up slightly.
• Minoxidil: no hormonal effect. Watch resting heart rate, blood pressure and weight on the oral form.

Effect on TRT gains: finasteride 5 mg did not reduce the strength, fat-free mass or bone gains of testosterone enanthate 125 mg/week in a 52-week trial of men aged 60+ (Borst 2014, PMID 24326421). Minoxidil has no plausible effect on gains.

Lean on finasteride when:

• Your only androgen is testosterone (TRT or a test-only cycle)
• Loss is early and you want to stop miniaturisation, not just regrow
• You have no history of sexual side effects on it

Lean on minoxidil when:

• Your stack includes DHT-derived compounds (masteron, primobolan, anavar, winstrol), which finasteride cannot reach
• Your stack includes nandrolone, where finasteride may make scalp effects worse
• You had or fear sexual side effects on a 5-alpha reductase inhibitor

Use both when: one alone is not holding your hairline. Topical minoxidil plus finasteride beat either alone on photographic scores in a meta-analysis of five trials (Chen 2020, PMID 32166351).

Be careful with oral minoxidil when: your resting heart rate is already high, your blood pressure is uncontrolled on cycle, or you have any history of heart failure or pericardial disease. Start with topical.

Monitor: DHT and PSA for finasteride; resting heart rate, blood pressure and morning weight for oral minoxidil.