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Hair Loss & DHT

The science of androgenetic alopecia and how to fight it

65–70%
serum levels
DHT reduction (finasteride)
~50%
of all men
Men affected by 50
~85%
with finasteride
Halt progression rate
3–6 mo
minimum
Time to see results

What Is Androgenetic Alopecia?

GeneticsAndrogenFollicle Miniaturization

    Androgenetic alopecia (AGA) is the most common form of hair loss, affecting roughly 50% of men by age 50. It is driven by a combination of genetic predisposition and androgen (hormone) activity — specifically DHT (dihydrotestosterone).

    AGA follows a predictable pattern: hair follicles in genetically susceptible areas (temples, crown) miniaturize over time — each hair cycle producing a finer, shorter hair until eventually the follicle stops producing hair altogether.

    The follicle doesn't die — it miniaturizes. This is why early intervention is so important.

What Is DHT?

DHT5-Alpha ReductaseAndrogen Receptor

    DHT (dihydrotestosterone) is a potent androgen derived from testosterone via the enzyme 5-alpha reductase (5-AR). It is roughly 3–5x more potent than testosterone in binding to androgen receptors.

    In hair follicles genetically sensitive to DHT, binding of DHT to the androgen receptor:

  • Shortens the anagen (growth) phase
  • Induces premature catagen (regression)
  • Causes progressive follicle miniaturization over successive cycles

    • Paradox: DHT promotes hair loss on the scalp, but promotes body and facial hair growth. This is due to follicle-specific androgen receptor expression and sensitivity.

Finasteride — How It Works

5-AR InhibitorFDA ApprovedOral Medication

    Finasteride is a Type II 5-alpha reductase inhibitor. It blocks the conversion of testosterone → DHT, reducing serum DHT by ~65–70% and scalp DHT by ~70%.

    FDA approved: 1 mg/day (Propecia) for male pattern hair loss since 1997.

    Efficacy:

  • Halts progression in ~85% of men
  • Regrowth seen in ~65% after 2 years
  • Most effective at the crown and mid-scalp
  • Takes 3–6 months to see initial results; 12–18 months for full effect

    • Side effects (5–8% reported):

  • Sexual side effects (decreased libido, erectile dysfunction, ejaculatory dysfunction)
  • Post-Finasteride Syndrome (controversial — small subset report persistent effects)
  • Slightly decreased PSA (relevant for prostate cancer screening)

    • Key point: Stop taking it and DHT rebounds — any hair gained is typically lost within 6–12 months.

Minoxidil — How It Works

VasodilatorAnagen ProlongationOTC + Oral

    Minoxidil was originally developed as an oral antihypertensive. Hair growth was discovered as a side effect. Topical formulations (2% and 5%) are now first-line OTC treatments for AGA.

    Mechanism (still not fully understood):

  • Opens ATP-sensitive potassium channels → vasodilation of scalp capillaries
  • Prolongs the anagen (growth) phase
  • May directly stimulate follicle proliferation via prostaglandin E2
  • Sulfotransferase enzymes in the scalp convert minoxidil to its active form (minoxidil sulfate) — enzyme expression predicts who responds

    • Topical (5% foam/liquid):

  • Applied once or twice daily
  • Shedding in weeks 1–8 is normal (anagen shift)
  • Results visible at 3–4 months; full effect at 12 months

    • Oral Minoxidil (0.25–2.5 mg/day):

  • More convenient, potentially more effective
  • Systemic side effects: fluid retention, unwanted body hair (hypertrichosis), reflex tachycardia at higher doses

Combination Protocol

ProtocolSynergyEarly Intervention

    Finasteride and minoxidil work via different mechanisms and are synergistic:

  • Finasteride — addresses the root cause (DHT suppression), stops progression
  • Minoxidil — promotes regrowth and extends growth phase independent of DHT

    • Evidence-backed stack:

    1. Finasteride 1 mg/day oral

    2. Minoxidil 5% topical once daily (or oral low-dose 0.25–1mg/day)

    3. Dermarolling (microneedling) 1.5mm — improves topical penetration and may stimulate growth factors independently

    4. Ketoconazole shampoo 2% — mild anti-androgen effect at scalp level

    Start early. Hair loss is easier to halt than reverse. Once follicles are gone, you need hair transplant.