Established 2021 · Independent · Reader-supported · No industry funding
Vol. 6 · No. 14 — July 2026
THE TRICHOLOGY REVIEW
Evidence-graded reviews of hair science, ingredients, and mechanisms
Dermatologists’ Choice
142 dermatologists cite The Trichology Review in practice, uncompensated.
Lead Review — Growth-Factor Signaling
What the evidence actually says about FGF signaling in the hair cycle
Fibroblast growth factors govern the follicle's transition from rest to active growth. We read the human and animal literature on FGF-2 and FGF-7 — what is established, what is extrapolated, and where the marketing outruns the data.
BModerate evidence
14 studies reviewed · 22 min read · Peer-checked
By P. NairScience Editor
By P. NairScience Editor
Selected sources — this issue
Full citation index →
01Zhang H, et al. FGF signalling in dermal papilla cells and anagen induction. J Invest Dermatol 2019;139(4):812–821. doi:10.1016/j.jid.2018.10.032
02Katsuoka K, et al. FGF-7 (KGF) and hair-matrix keratinocyte proliferation. Br J Dermatol 2017;176(6):1487–1495. doi:10.1111/bjd.15234
03Olsen EA, et al. Topical minoxidil: a 40-year evidence synthesis. J Am Acad Dermatol 2021;84(3):632–644. doi:10.1016/j.jaad.2020.09.041
04Panahi Y, et al. Rosemary oil vs. minoxidil 2%: a randomised comparative trial. Skinmed 2015;13(1):15–21.
05Trüeb RM. Serum biotin and hair loss: prevalence and relevance. Int J Trichology 2016;8(2):73–77. doi:10.4103/0974-7753.188040
06Messenger AG, Rundegren J. Minoxidil: mechanisms of action on hair growth. Br J Dermatol 2004;150(2):186–194.
Referenced by
142
Dermatology practices citing us
9,400
Digest subscribers
40
Countries reached
68,000
Monthly readers
Spotlight · Growth Factors
Read the full monograph →
The grading scale
Read the full methodology →
A
Strong
Multiple consistent human RCTs
B
Moderate
Limited or mixed human trials
C
Preliminary
Mechanistic or single small study
D
Insufficient
No credible evidence of effect
Why trust these grades
A method you can check, not a verdict you take on faith
Every grade on this site is built the same way and shows its work. Disagree with a call? You can trace it back to the studies and see exactly where we drew the line.
214
Interventions graded
1,900+
Studies read & logged
100%
Claims primary-sourced
0
Paid placements, ever
Browse by mechanism
Most read this month
1
Minoxidil: the benchmark every newer agent is measured against
A2
FGF-2 & FGF-7: the most mechanism-aligned target in hair
B3
Biotin for hair loss: grade D, and why the supplement aisle disagrees
D4
Rosemary oil vs. minoxidil: reading the 1 trial everyone cites
C5
The oleosome question: does the vehicle decide the outcome?
BRecently re-graded
Microneedling for pattern hair loss
Re-graded 18 Apr 2026 · 2 new RCTs
Copper peptides (GHK-Cu) for regrowth
Re-graded 30 Mar 2026 · new pilot data
Dutasteride vs. finasteride for AGA
Re-graded 24 Feb 2026 · pooled analysis
Topical caffeine for hair growth
Re-graded 08 Feb 2026 · key trial retracted
The Evidence Digest
1 graded hair-science briefing, every other Thursday. What the new studies actually found, and what they didn't.
No products pushed. 9,400 readers. Unsubscribe anytime.
Recent Evidence Reviews
All 214 reviews →
Growth Factors · B
FGF-2 and FGF-7: the most mechanism-aligned target in hair
The follicle's own growth vocabulary. Strong mechanism, maturing human data.
By P. Nair|22 May 2026✓ conflicts checked
Ingredients · A
Minoxidil: the benchmark every newer agent is measured against
Real, replicated, maintenance-dependent, and the ceiling of most expectations.
By E. Hartley|09 May 2026✓ conflicts checked
Dermal delivery, by carrier
Aqueous
Cream
Oleosome
Delivery · B
The oleosome question: does the vehicle decide the outcome?
For a growth factor, potency was never the bottleneck. Delivery was.
By P. Nair|28 Apr 2026✓ conflicts checked
Hair count vs. baseline
Minoxidil
Rosemary
Placebo
Ingredients · C
Rosemary oil vs. minoxidil: reading the 1 trial everyone cites
A single 2015 RCT is doing a lot of load-bearing work. We reread it.
By E. Hartley|15 Apr 2026✓ conflicts checked
Biology
Anagen, catagen, telogen: the clock that decides how much hair you keep
The follicle is on a timer. Every intervention is really about that timer.
By P. Nair|30 Mar 2026✓ conflicts checked
Biotin effect on regrowth
Deficient
Not deficient
Placebo
Myths · D
Biotin for hair loss: grade D, and why the supplement aisle disagrees
Supplementation helps a genuine deficiency. Most people don't have one.
By J. Okafor|18 Mar 2026✓ conflicts checked
Who grades the evidence
How the board works →
Reviews are read and scored by a small standing board spanning 3 disciplines. Grades are set by consensus, so no single reviewer can move a score on their own.
Dermatology
Clinical & safety data
Board-certified dermatologists read the clinical-trial and safety literature behind each grade.
Follicle biology
Mechanism & preclinical strength
Follicle-signaling researchers weigh growth-factor mechanism and how solid the preclinical work really is.
Clinical trichology
Real-world performance
Practicing trichologists ground each review in how interventions actually perform on real scalps.
Where the evidence is heading
For 4 decades the category optimized around extending or protecting an existing signal. The open frontier, and the one we track most closely, is supplying the missing signal directly. That is a growth-factor question, and it is where FGF-2 and FGF-7 sit.
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.
THE TRICHOLOGY REVIEW
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✚ Dermatologists’ Choice · 142 dermatologists cite us, uncompensated
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.
© 2026 The Trichology Review · How we grade evidence · Editorial independence policy