Treatment Science

Claim-by-claim evidence for major hair loss treatments, from FDA-approved drugs to peptides and branded supplements, matched to the model behind each claim.

Treatment science product capsules

45 Treatments and targets analyzed

Mapped across drugs, peptides, nutraceutical actives, and research programs.

Specialist reviewing branded product evidence

4 Branded products reviewed

Popular blends decoded with the same evidence framework.

Researchers reviewing clinical evidence

Unbiased Editorially independent

Evidence reviews built from source material, not brand sponsorship.

EVIDENCE LADDER

How we evaluate evidence

Every claim on this page is matched to one of these six tiers, ranked by how reliably the experimental model predicts what will happen in real human scalps.

MechanismTissue contextHuman proof
Tier 1

In Silico

Computer models spot possible pathways.

Proof weight
Very low
Tier 2

In Vitro

Cell tests show early biological activity.

Proof weight
Low
Tier 3

In Vivo

Whole-organism effects, before human data.

Proof weight
Moderate
Tier 4

Ex Vivo

Living human follicles outside the body.

Proof weight
Moderate-high
Tier 5

Open-Label

Human results, but without placebo control.

Proof weight
High
Tier 6

Human RCT

Blinded, placebo-controlled human proof.

Proof weight
Highest
Treatment Index

Evidence-ranked treatment index

Search, sort, and filter treatments, research targets, and brand reviews from one evidence index.

Finasteride
FDA-Approved
A
5/5
In VivoOpen-LabelRCT

Gold standard oral treatment for male AGA with decades of large RCT data proving it slows loss and regrows hair.

See evidence breakdown →
Minoxidil
FDA-Approved
A
5/5
In VitroIn VivoOpen-LabelRCT

The most widely studied hair growth agent with 35+ years of RCT evidence in both men and women.

See evidence breakdown →
Dutasteride
Off-Label
B
4/5
Open-LabelRCT

Most potent 5-alpha reductase inhibitor with RCT evidence of superiority over finasteride.

See evidence breakdown →
Ketoconazole
Off-Label
B
3/5
In VitroIn VivoOpen-LabelRCT

Well-tolerated adjunct with antifungal, anti-inflammatory, and potential anti-androgenic properties.

See evidence breakdown →
Latanoprost
Off-Label
C
4/5
In VivoEx VivoOpen-LabelRCT

Strong prostaglandin biology and one small positive RCT for scalp, but validated only for eyelash growth (via bimatoprost/Latisse)

See evidence breakdown →
Levocetirizine
Off-Label
C
3/5
In SilicoIn VitroIn VivoEx VivoOpen-LabelRCT

Compelling PGD2-based rationale and consistently positive clinical signals with cetirizine, but no large definitive trial — best used as an adjunct to proven treatments

See evidence breakdown →
TDM-105795
Investigational
D
3/5
In VivoRCT

First-in-class thyromimetic with Phase 2a data showing modest hair count increases.

See evidence breakdown →
Liothyronine (T3)
Off-Label
D
2/5
In VivoEx VivoRCT

Compelling mechanistic biology and strong ex vivo data, but no positive human clinical trial for hair loss

See evidence breakdown →
PP405
Investigational
D
2/5
In VivoEx VivoOpen-Label

First-in-class metabolic approach with strong preclinical rationale, early positive Phase 2a signal, but very limited clinical data and no peer-reviewed publications.

See evidence breakdown →
Acetyl Tetrapeptide-3 (Capixyl)
Peptides / Cosmeceuticals
D
2/5
In VitroRCT

Two-component complex with plausible mechanisms but thin clinical evidence and key claims traceable to fabricated citations.

See evidence breakdown →
Biotinoyl Tripeptide-1 (Procapil)
Peptides / Cosmeceuticals
D
2/5
In VitroIn VivoEx VivoRCT

Three-ingredient complex with plausible biology but widely misrepresented marketing claims and no peer-reviewed human trial of the peptide alone.

See evidence breakdown →
GHK-Cu
Peptides / Cosmeceuticals
D
2/5
In SilicoIn VitroIn VivoOpen-Label

Strong preclinical rationale from wound healing and genomics, but no rigorous human trial of topical GHK-Cu alone for hair loss.

See evidence breakdown →
TB-500 / Thymosin Beta-4
Peptides / Cosmeceuticals
D
2/5
In VivoRCT

Strongest preclinical hair biology of any peptide, but zero human hair trials -- best evidence is for wound healing, dry eye, and cardiac repair.

See evidence breakdown →
Iron
Nutraceutical
D
2/5
Open-Label

A genuine cause of reversible hair shedding in iron-deficient patients — but useless and potentially harmful if your iron stores are normal.

See evidence breakdown →
Saw Palmetto
Nutraceutical
D
2/5
In VitroOpen-LabelRCT

A botanical 5-alpha reductase inhibitor whose only high-quality trials (in BPH) showed no benefit over placebo; the positive AGA data are small and low-quality.

See evidence breakdown →
Tocotrienol
Nutraceutical
D
2/5
RCT

One small Malaysian RCT showed a hair-count increase. Never replicated. Used by Nutrafol to justify its tocotrienol content.

See evidence breakdown →
Vitamin D
Nutraceutical
D
2/5
In VitroOpen-Label

Correlated with AGA in observational studies. No RCT yet shows that supplementation reverses or slows hair loss.

See evidence breakdown →
BPC-157
Peptides / Cosmeceuticals
D
1/5
In SilicoIn VivoOpen-Label

Strong tissue repair peptide with zero evidence for hair loss — a category error when applied to the scalp.

See evidence breakdown →
Curcumin
Nutraceutical
D
1/5
In VitroOpen-Label

Generic anti-inflammatory rationale; no AGA-specific RCT support and abysmal oral bioavailability.

See evidence breakdown →
Niacin
Nutraceutical
D
1/5
Open-Label

Severe deficiency (pellagra) causes alopecia. In a normal-diet adult, niacin supplementation does nothing for hair.

See evidence breakdown →
Niacinamide (Topical)
Nutraceutical
D
1/5
In VitroOpen-Label

Well-established skin-barrier ingredient. Modest hair-shaft data; no AGA RCT.

See evidence breakdown →
Vitamin A
Nutraceutical
D
1/5
Open-Label

Severe deficiency causes hair changes — but excess vitamin A is a well-documented cause of hair loss. The supplement industry rarely mentions that.

See evidence breakdown →
Vitamin B12
Nutraceutical
D
1/5
Open-Label

Helps if you're a vegan, elderly, or have pernicious anemia. Otherwise no AGA benefit.

See evidence breakdown →
Vitamin B6
Nutraceutical
D
1/5
Open-Label

Cofactor with no direct AGA evidence. Deficiency rare; mega-doses cause peripheral neuropathy.

See evidence breakdown →
Zinc
Nutraceutical
D
1/5
In VitroOpen-Label

Useful for confirmed zinc deficiency. No AGA benefit in zinc-replete adults; mega-doses cause copper deficiency.

See evidence breakdown →
Ashwagandha
Nutraceutical
F
1/5
Open-Label

Real stress-reduction evidence; zero direct evidence for AGA. Included in supplements on inferential 'stress → hair loss' logic.

See evidence breakdown →
Beta-Sitosterol
Nutraceutical
F
1/5
Open-Label

Tested only in combination with saw palmetto. Standalone AGA effect unknown.

See evidence breakdown →
Biotin
Nutraceutical
F
1/5
Open-LabelRCT

The most-marketed hair vitamin, with no controlled evidence it works in anyone who is not deficient, and a documented habit of corrupting thyroid and cardiac blood tests.

See evidence breakdown →
Marine Collagen
Nutraceutical
F
1/5
Open-Label

The signature ingredient of Viviscal — a proprietary marine peptide blend with no isolated-ingredient peer-reviewed AGA evidence.

See evidence breakdown →
Vitamin C
Nutraceutical
F
1/5
Open-Label

A required nutrient with no direct AGA evidence. Useful only as an iron-absorption cofactor in patients supplementing iron.

See evidence breakdown →
Bamboo Silica
Nutraceutical
F
0/5
Open-Label

Silica source with no AGA evidence.

See evidence breakdown →
Calcium
Nutraceutical
F
0/5
Open-Label

Bone mineral with no documented hair-loss role. Filler in multivitamin-style hair supplements.

See evidence breakdown →
Fo-Ti
Nutraceutical
F
0/5
Open-Label

Traditional medicine ingredient with no quality RCTs — and documented hepatotoxicity case reports.

See evidence breakdown →
Horsetail
Nutraceutical
F
0/5
Open-Label

Traditional silica source with no quality AGA evidence.

See evidence breakdown →
Iodine
Nutraceutical
F
0/5
Open-Label

Real iodine deficiency does affect hair via thyroid — but in iodized-salt populations, supplementing extra iodine is unnecessary and can harm.

See evidence breakdown →
L-Tyrosine
Nutraceutical
F
0/5
Open-Label

Amino acid precursor with no direct AGA evidence.

See evidence breakdown →
Mung Bean
Nutraceutical
F
0/5
Open-Label

Vegamour's signature ingredient. No peer-reviewed AGA evidence.

See evidence breakdown →
Nettle Root
Nutraceutical
F
0/5
In Vitro

Weak in vitro 5-AR inhibition; no human AGA RCT.

See evidence breakdown →
Peony Root
Nutraceutical
F
0/5
Open-Label

Traditional medicine ingredient with no AGA evidence.

See evidence breakdown →
Red Clover
Nutraceutical
F
0/5
In Vitro

Weak in vitro phytoestrogen activity; no human AGA evidence.

See evidence breakdown →
Selenium
Nutraceutical
F
0/5
Open-Label

Both deficiency and excess cause hair loss; supplementation in adequately-fed adults has no AGA benefit.

See evidence breakdown →
Spirulina
Nutraceutical
F
0/5
Open-Label

Generic dietary protein/micronutrient with no AGA evidence.

See evidence breakdown →
Vitamin E
Nutraceutical
F
0/5
Open-Label

The common vitamin E form. Distinct from tocotrienol, which is the form with the single small Malaysian RCT. No alpha-tocopherol AGA evidence.

See evidence breakdown →