Encyclopedia | Hairmetry

A

protein or peptide

Acetyl tetrapeptide-3

Acetyl tetrapeptide-3 is a short peptide sold in hair serums, almost always with biochanin A; one small trial of a three-part blend matched 3% minoxidil.
drug with hair side effects

Acitretin

A prescription retinoid for severe psoriasis whose most common side effect is hair thinning, and which must never be used in pregnancy.
growth stimulant

Adenosine (topical)

Adenosine, a natural signalling molecule, is the cosmetic hair active with the cleanest small placebo-controlled trials, mainly making thin hairs thicker.
protein or peptide

AHK-Cu (copper tripeptide-3)

AHK-Cu is a copper peptide that lengthened human hair follicles in a 2007 lab study but has no human hair-growth trial.
antiandrogen

Alfatradiol

A weakly hormonal topical estradiol approved for pattern hair loss in Germany; in the one randomised comparison it only slowed loss while minoxidil grew hair.
supplement

Alpha-ketoglutarate (and alpha-ketobutyrate)

Two ordinary body metabolites woke dormant mouse hair follicles in a 2019 study, and oral alpha-ketobutyrate prevented hair loss in aged mice, but there is no human data.
other

Aminexil

Aminexil is a minoxidil-like cosmetic sold as an anti-shedding ampoule, with no human trial and a rat study that found it the weakest of the products tested.
botanical

Amla

Amla fruit has one small positive placebo-controlled trial of an oral syrup in women with pattern hair loss, plus lab and animal data; amla oils and masks are tradition.
botanical

AnaGain

AnaGain is a pea sprout extract with a small maker-run study and mouse data, plausible and low risk but without an independent controlled trial.
drug with hair side effects

Anticoagulants (heparin, warfarin, DOACs)

Blood thinners that can cause shedding about 3 months after starting, which usually reverses and is never a reason to stop on your own.
drug with hair side effects

Antithyroid drugs (carbimazole, methimazole, propylthiouracil)

Medicines for an overactive thyroid; shedding on them can come from the thyroid disease, an over-treated thyroid, or the drug, which is hard to separate.

B

botanical

Baicapil

Baicapil is a supplier-branded plant-extract active found in hair serums, with no published human trial behind it.
drug with hair side effects

Beta-blockers

Heart and blood-pressure drugs that rarely cause reversible shedding, based on old case reports only.
botanical

Bhringraj

Bhringraj is the Ayurvedic "king of hair" herb; extracts speed regrowth in rats and mice, but no human hair trial was found.
antiandrogen

Bicalutamide

A prostate-cancer drug that blocks the androgen receptor and is used off-label by some specialists for women's hair loss, with liver-monitoring and pregnancy rules.
supplement

Biotin

A B vitamin that restores hair only in the rare people who are deficient, and that can scramble thyroid and heart blood tests at the doses sold for hair.
protein or peptide

Biotinoyl tripeptide-1

Biotinoyl tripeptide-1 is biotin attached to the GHK peptide; the only hair-growth data are manufacturer claims.
botanical

Black seed oil

Black seed oil's hair reputation rests on animal work and a tiny open-label lotion study, with no independent controlled human trial.
drug with hair side effects

BRAF inhibitors (vemurafenib, dabrafenib)

Melanoma pills that caused hair loss in 2 of 20 patients and curly hair in one in a small prospective study.
drug with hair side effects

Breast cancer endocrine therapy (tamoxifen, aromatase inhibitors)

Anti-estrogen pills taken for years after breast cancer can cause female pattern-type thinning, and in one uncontrolled series topical minoxidil helped 80% of those assessed.

C

growth stimulant

Caffeine (topical)

Caffeine in shampoos and leave-on liquids clearly stimulates hair follicles in the lab, but the human trials are small, mostly industry-run and mostly on blends.
botanical

Cannabinoids and CBD

A hemp-oil case series claims a 93.5% rise in hair count in 35 people, but it had no control group; lab data hint CBD may lift a growth signal in papilla cells while higher doses could push follicles into regression.
protein or peptide

Capixyl

Capixyl is a branded blend of a peptide and a red clover isoflavone; one tiny trial of a similar blend matched 3% minoxidil, with no placebo arm.
supplement

Capsaicin and isoflavone (oral)

One 2007 Japanese study found more hair growth in people taking oral capsaicin plus soy isoflavone than placebo, but it was never replicated, and capsaicin applied directly to follicles in the lab does the opposite.
drug with hair side effects

CDK4/6 inhibitors (palbociclib, ribociclib, abemaciclib)

Breast-cancer pills that cause a thinning pattern similar to androgenetic alopecia, concentrated at the crown, with a slightly weaker response to minoxidil than with hormone therapy alone.
drug with hair side effects

Chemotherapy hair changes ("chemo curls")

Hair often regrows curlier, softer or a different colour after chemotherapy, but nobody has measured how often; what is better documented is that permanent thin regrowth is more common than once believed.
antiandrogen

Clascoterone

A topical androgen blocker already approved as an acne cream whose 5% scalp solution reported positive phase 3 results in men; it is not yet approved for hair.
protein or peptide

Collagen peptides

A protein powder with modest skin evidence and very little for hair.
antiandrogen

Cyproterone acetate

A steroid antiandrogen used in Europe for women's hair loss and excess hair, with mixed trial results and a dose-related risk of meningioma.

D

pathway modulator

Dipyridamole

An old antiplatelet pill that on paper boosts the same adenosine pathway topical adenosine uses, but no study has ever tested it on hair and its label lists hair loss as a rare report.
antiandrogen

Dutasteride

A stronger cousin of finasteride that blocks both forms of the DHT-making enzyme and grew more hair than finasteride in head-to-head trials.

F

botanical

Fenugreek

A seed used in traditional hair oils and masks with no human hair-growth trial behind it.
antiandrogen

Finasteride

A prescription pill (and in some countries a scalp spray) that lowers DHT and is the best-proven drug for stopping male pattern hair loss.
antiandrogen

Flutamide

An older prostate-cancer antiandrogen that helped women's hair loss modestly in one small trial but carries a boxed warning for liver failure.

G

protein or peptide

GHK-Cu (copper tripeptide-1)

GHK-Cu is a copper-binding peptide with a long skin-repair record but no published controlled trial for hair growth.
drug with hair side effects

GLP-1 receptor agonists (semaglutide, tirzepatide)

The new weight-loss injections list hair shedding as a side effect in about 3-6% of trial participants versus about 1% on placebo, far more often in women, and it appears tied to weight loss rather than toxicity to follicles.
botanical

Green tea EGCG

EGCG, the main green tea catechin, grew human hair follicles in a dish, but there is no good human trial of it alone for hair loss.

H

supplement

Hair supplement blends (Nutrafol, Viviscal and similar)

Branded multi-ingredient hair vitamins that beat placebo in small, mostly company-linked trials.
drug with hair side effects

Hedgehog pathway inhibitors (vismodegib, sonidegib)

Skin-cancer pills that block the Hedgehog pathway, which drives follicle growth, caused hair loss in 56.9% of patients in a meta-analysis, the highest of any targeted cancer drug.
growth stimulant

HMI-115

An injected antibody that blocks the prolactin receptor, with a small open-label hair gain and an unreported 192-man phase 2 trial in men.

I

supplement

Iron and ferritin

Low iron stores are common in people who shed hair, but no trial has shown that iron pills regrow hair, and nobody agrees on a hair-specific ferritin target.
drug with hair side effects

Isotretinoin

A prescription acne drug that causes shedding in a few percent of users and, far more seriously, severe birth defects.

K

anti dandruff

Ketoconazole

An antifungal shampoo ingredient that is among the best-proven treatments for dandruff and, with much weaker evidence, a possible add-on for pattern hair loss.
growth stimulant

Kopexil

Kopexil is a minoxidil look-alike sold in cosmetic serums; a 2025 mouse study found it beat minoxidil, but there is no published human trial.

L

supplement

L-cysteine

An amino acid that makes up much of hair keratin, with no controlled hair trial on its own.
growth stimulant

Latanoprost

A cheap glaucoma eye drop that lengthens and darkens eyelashes, with only a small pilot trial behind its off-label use on the scalp.
botanical

Lavender oil

Lavender oil thickened skin and increased follicle numbers in mice in 2016; there is no human hair trial, and a debated hormone-disruption concern exists in young children.
drug with hair side effects

Lithium

A mood-stabilising medicine whose label lists hair thinning, with figures ranging from no excess in trials to about 1 in 5 in older surveys.

M

supplement

Marine protein supplements (Viviscal, Nourkrin)

Branded fish- and shellfish-extract pills with positive but small, manufacturer-linked trials.
growth stimulant

Melatonin (topical)

Hair follicles make their own melatonin, and a small 2004 trial found a scalp solution raised the share of growing hairs in women, but later studies are uncontrolled and sponsored by the maker.
drug with hair side effects

Metformin

The world's most-used diabetes pill woke sleeping hair follicles in mice and was linked to regrowth in 6 of 12 women with a scarring alopecia, but there is no randomized hair trial and it is not a baldness treatment.
drug with hair side effects

Methotrexate

A weekly immune-suppressing medicine that thins hair in a few percent of users, and is also used off-label for severe alopecia areata.
other

Methyl nicotinate

Methyl nicotinate makes skin flush and tingle by widening small blood vessels, but no controlled trial shows it grows hair.
growth stimulant

Minoxidil

The most widely used hair-growth treatment, available as a cheap over-the-counter lotion or foam and as a prescription tablet, with a mechanism that is still only partly understood.

N

supplement

NAD+ precursors (NMN, nicotinamide riboside)

The headline anti-ageing supplements have exactly one hair paper, in DHT-treated mice and cells, and no human hair trial.
other

Nanoxidil

Nanoxidil is a marketing name for a cosmetic "minoxidil alternative" with no chemical definition and no peer-reviewed study that could be found.
other

Niacinamide

Niacinamide is a safe, cheap vitamin B3 form found in many hair serums, but no trial shows it grows hair on its own.

O

supplement

Omega-3 fatty acids

Fish-oil fats whose only hair evidence is a branded omega-3/6 plus antioxidant product tested in women.
antiandrogen

Oral contraceptives and antiandrogenic progestins

Some birth-control pills lower androgens or block their receptor, but almost no trial shows that any pill regrows scalp hair.
protein or peptide

Osteopontin

Hairy moles are hairy because senescent pigment cells release osteopontin, which woke hair stem cells in mice and stimulated human follicles in culture, while a modified fragment of the same protein did the opposite.

P

botanical

Peppermint oil

In a 2014 mouse study 3% peppermint oil grew more hair than 3% minoxidil, but no human trial of peppermint oil for hair has been found.
growth stimulant

PP405

An experimental once-daily scalp gel that wakes dormant follicle stem cells; a small phase 2a trial found no blood absorption, and a 600-man trial began enrolling in September 2026.
protein or peptide

Procapil

Procapil is a branded trio of a biotin-linked peptide, apigenin and oleanolic acid sold as a hair-anchoring active, with small studies that are mostly add-ons to other treatments.
botanical

Procyanidin B2

Procyanidin B2, an apple polyphenol, beat placebo in two small related industry-run Japanese trials and one oral apple-extract trial, but nobody has replicated them independently.
botanical

Pumpkin seed oil

A food oil with two small randomised trials for pattern hair loss that look promising but are short, single-centre and unreplicated.
antiandrogen

Pyrilutamide

A topical androgen blocker from the Chinese company Kintor that reported positive pivotal results in China; no peer-reviewed efficacy paper yet.

R

botanical

Red ginseng

Red ginseng and red ginseng oil sped hair regrowth in mice and stimulated cultured papilla cells, but no controlled human trial of ginseng alone for hair loss exists.
botanical

Redensyl

Redensyl is a branded cosmetic blend marketed to wake follicle stem cells, with one small vehicle-controlled trial in a blend and several maker-linked open-label studies.
botanical

Rosemary oil

Rosemary oil became the internet's "natural minoxidil" from one small 2015 trial that had no placebo group and has never been replicated.

S

botanical

Saw palmetto

A berry extract with weak DHT-blocking activity that shows small benefits in short, mostly industry-linked trials and clearly less than finasteride in the one head-to-head.
protein or peptide

SCUBE3

A protein released by the hair follicle's command centre only while hair is growing; injecting it into mouse skin was enough to start new growth, with no human data yet.
pathway modulator

Senolytics (dasatinib plus quercetin, fisetin)

Drugs that clear aged "zombie" cells restored the hair-making ability of old human papilla cells in a dish, and fisetin and quercetin grew hair in mice, with no human hair trial.
supplement

Silicon (orthosilicic acid)

A silicon supplement that improved strength and thickness of fine hair in one supplier-run trial.
supplement

Spermidine

A natural compound sold as a longevity supplement lengthened human hair follicles grown in a dish at tiny concentrations, but nobody has shown it grows hair on a head.
antiandrogen

Spironolactone

A cheap blood-pressure pill that blocks androgen receptors and is the most widely used off-label hormonal treatment for women's pattern hair loss.
other

Stemoxydine

Stemoxydine is a cosmetic compound from L'Oréal pitched as mimicking the low-oxygen niche of follicle stem cells, with no peer-reviewed trial.

T

growth stimulant

Topical cetirizine

The common allergy antihistamine, made up as a 1% scalp solution, has several small trials suggesting a modest effect that is weaker than minoxidil.
growth stimulant

Tretinoin

A prescription acne and anti-ageing cream used off-label as a minoxidil booster because it increases minoxidil absorption, though the one randomised trial found no extra hair benefit.

U

supplement

Urolithin A

A gut-bacteria product of pomegranate and walnut compounds, sold as a mitochondria longevity supplement, protected human hair-papilla cells from oxidative damage in a brand-new 2026 company-linked paper, with no controlled human hair trial.

V

growth stimulant

Valproic acid (sodium valproate)

A seizure and mood-stabiliser drug that grew hair as a scalp spray in one tiny trial, but taken by mouth commonly causes hair shedding and is a major birth-defect risk.
supplement

Vitamin D

Hair loss goes with low vitamin D and the receptor is needed for the hair cycle, but no good trial shows supplements regrow hair if you are not deficient.
supplement

Vitamin E and tocotrienols

One small 8-month trial of tocotrienols reported more scalp hairs, with a manufacturer link and no replication.

Z

supplement

Zinc

True zinc deficiency causes hair loss that zinc fixes, but zinc has not been shown to regrow hair in people who are not deficient, and too much causes copper deficiency.

Every molecule that touches your hair

A

B

C

D

F

G

H

I

K

L

M

N

O

P

R

S

T

U

V

Z