Baseline Miniaturized Follicle
Androgenic hair loss shortens anagen, shrinking follicles over cycles.
- 2–6: Normal anagen phase (years, healthy scalp)
- <12: Miniaturized anagen (weeks, affected follicle)
- ~50%: Follicle diameter loss (vs healthy baseline)
- 3: Hair cycle stages (anagen, catagen, telogen)
Why follicles miniaturize
Genetic sensitivity to DHT shrinks the dermal papilla and shortens anagen.
Shorter anagen means finer, shorter hairs each cycle.
The three-phase hair cycle
Anagen (growth), catagen (transition), telogen (rest) repeat over years.
Visible effect
Thinner shafts, more telogen hairs, gradual density loss over time.
Topical Application & Absorption
Minoxidil crosses stratum corneum and reaches the dermal follicle unit.
- 2% / 5%: Common concentrations (topical solution/foam)
- ~1.4%: Skin penetration (of applied dose absorbed)
- Minoxidil sulfate: Active metabolite (via sulfotransferase enzyme)
- 2×/day: Application frequency (typical regimen)
Crossing the barrier
Lipophilic minoxidil diffuses through stratum corneum into dermis.
Local bioactivation
Follicular sulfotransferase converts minoxidil to its active sulfate form.
Dose matters
5% solution delivers more active drug to follicle than 2%.
Vasodilation & Potassium Channel Opening
Minoxidil sulfate opens ATP-sensitive K⁺ channels, dilating vessels and cells.
- K_ATP: Channel type (ATP-sensitive potassium channel)
- Vasodilation: Vessel effect (increased scalp perfusion)
- up to 45%: Blood flow increase (relative to baseline)
- Hyperpolarization: Cellular effect (smooth muscle & follicle cells)
K⁺ channel opening
Potassium efflux hyperpolarizes cell membranes, relaxing vessel walls.
Increased perfusion
Dilated vessels deliver more oxygen and nutrients to the follicle.
Growth factor signaling
Improved flow supports VEGF and other pro-growth signaling pathways.
Anagen Phase Prolongation
Nourished follicle cells stay in active growth longer before resting.
- +30–55: Anagen extension (relative days, simulated)
- Anagen-shifted: Follicle cell state (matrix cells reactivate)
- Prolonged: Catagen delay (growth phase extended)
- ~4–8: Response onset (weeks typical)
Extending growth
Anagen duration lengthens, allowing hairs to grow longer and thicker.
Cell reactivation
Resting telogen follicle cells shift back into active anagen state.
Cumulative effect
Consistent use compounds phase extension over successive hair cycles.
Thicker, Longer Hair Over Months
Early shedding clears weak hairs, then thicker strands regrow steadily.
- wk 2–4: Initial shedding window (weak hairs pushed out)
- ~8–16: Visible improvement (weeks of consistent use)
- up to +58%: Diameter gain (relative, simulated model)
- Reversible: Discontinuation effect (benefit fades if stopped)
The shedding phase
New anagen hairs push out old telogen hairs — a good sign.
Regrowth curve
Diameter and length climb steadily after the initial shedding dip.
Maintaining results
Effect requires continued use; stopping reverses gains over months.