The Trichology Review

Established 2021 · Independent · Reader-supported · No industry fundingVol. 6 · No. 14 — July 2026

Hair Biology Ingredients Growth Factors Reviews Myths How We Grade The Digest Take the Quiz

Evidence status: current·Last updated 12 Jun 2026 · v2.3·Revision history

Interactive · Drag or press play

The hair cycle, scrubbed

Move through a single follicle's life, from active growth to rest, and watch when the growth signal is switched on, and when it goes quiet.

CROSS-SECTION

dermal papilla

Duration

Follicles here

FGF-2 / FGF-7 signaling: {{ fgfLabel }}

ANAGEN

CAT.

TELOGEN

cycle position: {{ posLabel }}

Notice the pattern: growth-factor signaling is on through anagen and off in rest. Pattern hair loss shortens anagen, less time with the signal on. The whole growth-factor thesis is about restoring that signal to a follicle stuck in the quiet part of the cycle. Read the FGF monograph →

The full biology primer

→

What does the evidence suggest for you?

→

Referenced by

VogueAllureHarper’s Bazaarbyrdiewell+goodCosmopolitanGlamourmarie clairerefinery29InStyleDermatology TimesPractical DermatologyCosmetics & ToiletriesVogueAllureHarper’s Bazaarbyrdiewell+goodCosmopolitanGlamourmarie clairerefinery29InStyleDermatology TimesPractical DermatologyCosmetics & Toiletries

142

Dermatology practices citing us

9,400

Digest subscribers

Countries reached

68,000

Monthly readers

✚Dermatologists’ Choice — 142 dermatologists cite The Trichology Review in practice, uncompensated.

THE TRICHOLOGY REVIEW

contact@thetrichologyreview.org

An independent, reader-supported publication. We accept no advertising from ingredient or product manufacturers.

✚ Dermatologists’ Choice · 142 dermatologists cite us, uncompensated

READ

Hair Biology Growth Factors Reviews Myths

ABOUT

Methodology Conflicts The Digest

TOOLS

Evidence Quiz Cycle Interactive

Grade Alerts

Grades for hair treatments change. Know when they do. Get an alert when a grade moves, plus each new review. About 2 emails a month. No products, no sponsors.