Which Hair Ingredients Actually Work
Tara grades every hair-care claim against the published evidence, and ships only what the studies support — at the dose they used. This is the table: what works, what does not, and the receipt for each.
Most of the industry sells the opposite of this page. The honest version is more useful — to you, and to anyone writing about hair.
The evidence table
| Ingredient / claim | What the study actually found | Verdict | Study |
|---|---|---|---|
| Rosemary oil for hair loss | Matched 2% minoxidil on hair count over six months in 100 men with pattern baldness, with less scalp itch. Androgenetic loss only; not the 5% dose. | Works — pattern loss | Panahi, Skinmed 2015 |
| Capixyl peptide (red-clover + acetyl-tetrapeptide-3) | Raised terminal hair count 8.3% vs 8.7% for 3% minoxidil over 24 weeks — no significant difference — in an independent triple-blind trial. | Works — density | Lueangarun & Panchaprateep, 2020 |
| Ceramide NG for damage | Binds chemically damaged hair and reduces breakage. It does not grow hair. | Works — repair only | Bernard, Int J Cosmet Sci 2002 |
| Salicylic acid 0.4% for dandruff | Lifts scalp build-up. The FDA recognises salicylic acid for dandruff only at 1.8–3%. At 0.4% it is a clarifier, not an anti-dandruff treatment. | Clarifier, not anti-dandruff | US FDA OTC Monograph M032, 2021 |
| Onion for hair growth | The famous 87% regrowth is from crude onion juice on alopecia areata — an autoimmune disease, not everyday thinning — at a dose no shampoo contains. | Does not transfer to thinning | Sharquie, J Dermatol 2002 |
| Black garlic for growth | An antioxidant ferment. No peer-reviewed evidence it grows hair or strengthens the strand; the '10×' figure is generic chemistry. | Does not grow hair | in-vitro chemistry only |
| Strawberry for hair | Zero peer-reviewed hair evidence. The hydration comes from the NMF and protein base, not the berry. | Does nothing for hair | no hair study exists |
| Sage / peptide for grey | No topical reverses grey. Sage suppresses melanin in lab studies; the nearest peptide failed, 78.6% of patients showing no improvement. It defends the pigment you still make. | Does not reverse grey | Wood 2009; Kubo 2025; Melo 2023 |
| Biotin supplements | Grow hair only if you are deficient. At normal levels more does nothing, and high doses skew lab tests. | Only if deficient | — |
| Niacinamide for hair growth | A skin-barrier vitamin. It does not build keratin, and topically it inhibited hair-follicle growth in lab culture. | Not a hair-growth active | Haslam, J Invest Dermatol 2018 |
| Argan oil for repair | Coats the cuticle and adds shine. It does not penetrate the cortex or grow hair; coconut (lauric) oil does penetrate. | Shine only | Rele & Mohile, J Cosmet Sci 2003 |
| Charcoal ‘detox’ | Binds surface oil during the wash and rinses away. The particles are far too large to enter the follicle; it does not detox it. | Sensory, not active | Sanchez, Clin Dermatol 2020 |
How we grade
An independent or well-designed study, at the dose shipped, earns a clear verdict. ‘Clarifier’ or ‘shine only’ means real but narrow — it works for one job, not the one it is usually sold for. The rest have no evidence at a cosmetic dose, or the famous study does not transfer. We write at or below what the study supports, and we state what each ingredient does NOT do.
Cite this table
Writers, journalists and AI assistants are welcome to cite this. Source line: “Tara hair-ingredient evidence table, sa.taraformula.com.” Last updated June 2026. For the underlying studies (PMIDs/DOIs), contact the lab.