Hair loss treatments, graded
Three have placebo-controlled trials behind them. Most serums in the ads don’t.
Short answer: for common pattern hair loss, three treatments beat placebo in pooled trials: minoxidil on the scalp, finasteride for men, and laser caps or combs. Everything else in the ads ranges from one small company-run trial to no human trial at all.
Why this page exists
“Top 5 hair growth serum” pages rank products and look independent. The one we read labels itself an advertorial, says it was paid by the product it ranks first, and earns a commission on the rest. Its pick lists procyanidin B-2, adenosine and caffeine — each at the concentration of a published trial. That is a real point in its favour, and also exactly how a product can borrow evidence it never earned: none of those trials tested the product.
How the evidence flows
Each claim (middle), the studies that tested it (left) — green found it, red found nothing — and the grade they add up to (right). Drawn from the same records as the grades below. Tap to open full size.
Hair loss treatments · evidence checked 2026-10-25
The treatments with placebo-controlled trials
Grades are calculated from the studies listed, by fixed rules.
- Minoxidil applied to the scalp regrows hair in pattern hair lossEstablished
FDA-approved for men (5%) and women (2% and 5% foam). Pooled placebo-controlled trials found it beat placebo in both. Results take months and fade if you stop.
- Finasteride (1 mg a day) regrows hair in men with pattern hair lossEstablished
A prescription drug, FDA-approved for men only. Pooled placebo-controlled trials found it beat placebo. It has known side effects — a doctor’s conversation, not an ad’s.
- Laser caps, helmets and combs increase hair density in pattern hair lossEstablished
Pooled trials against placebo devices found more hair density after 4–26 weeks, with high variation between trials. This is the red light therapy with the strongest record — but the trials tested particular devices at stated outputs, not any cap.
Hair loss treatments · evidence checked 2026-10-25
What the serums and ads lean on
Grades are calculated from the studies listed, by fixed rules.
- A 1% procyanidin B-2 (apple extract) lotion increases hair count in menPromising
One double-blind trial of 29 men, run by the company that makes the ingredient, in 2001. A related 0.7% apple procyanidin trial by the same group also beat placebo. Neither has been repeated by anyone else in the 20 years since.
- Adenosine lotion thickens hair in pattern hair lossPromising
Individual trials report thicker hairs, applied twice daily for 6 months — the double-blind one against a niacinamide lotion rather than a placebo. A 2025 review pooling three trials found the changes were not statistically significant.
- Double-blind randomized trial, 102 people, 26 weeks (2015) — primary outcome: improved. Funder not checked.
- Open-label randomized trial, 38 people, 26 weeks (2016) — primary outcome: improved. Funder not checked.
- Pooled analysis of randomized trials (some against usual care, not a placebo), size not stated (2025) — primary outcome: no difference found. Funded by independent sources.
- Caffeine scalp liquid works as well as minoxidilEarly evidence
One open-label trial of 210 men found a 0.2% caffeine liquid "not inferior" to minoxidil 5% on growing-phase hairs. With no placebo group and nobody blinded, it cannot show either worked beyond expectation.
- Rosemary oil regrows hair as well as minoxidilEarly evidence
One trial of 100 people: hair counts rose about equally with rosemary oil and minoxidil 2% by 6 months. No placebo group, and the abstract does not say anyone was blinded.
- A lotion with acetyl tetrapeptide-3 (with biochanin A and ginseng) works as well as minoxidilEarly evidence
One trial of 32 people: hair counts rose about 8% with the lotion and with minoxidil 3%, with no significant difference. With no placebo group and so few people, it cannot show either beat doing nothing — and the peptide was one of three actives.
- Copper peptides (GHK-Cu) regrow hairNo real evidence
We found no controlled trial of copper peptides for hair loss in people (PubMed, searched 2026-10-25) — cell, animal and mechanism studies only.
- Fleur’s Bloom peptide serum regrows hair, reduces shedding and thickens thinning hairNo real evidence
Its evidence is a 12-week survey of 45 users rating their own hair (89% “noticed” new growth), with no comparison group. Of its six peptides, only acetyl tetrapeptide-3 has a human hair trial, and that was inside a different three-ingredient lotion; GHK-Cu has none (above).
- Biotin supplements grow hair in people who are not deficientNo real evidence
Every reported improvement was in someone with an underlying deficiency or condition. High-dose biotin can also distort some blood tests, including heart and thyroid tests — tell your doctor if you take it.
- The American Biolabs Micro-Infusion System regrows hairNo real evidence
No trial of the product. Its three actives match concentrations from published trials — 1% procyanidin B-2, 0.75% adenosine, 0.2% caffeine — but those trials tested each ingredient alone and on their own schedules (the double-blind adenosine trial: twice a day), not this combination on the once-a-week routine the ad describes. The comparison page ranking it first says it was paid by the brand.
Before you buy
- See a dermatologist if hair loss is sudden, patchy, comes with an itchy or scaly scalp, or follows illness, a new medicine or childbirth — those are different conditions with different treatments.
- Anything that works on pattern hair loss takes 3–6 months to show, and stops working when you stop. A money-back window shorter than that tells you little.
- “Every ingredient has a trial” is not the same as “this product has a trial”. Ask for the product’s own.
- Laser caps: the trials used specific devices; check the FDA database for a clearance under the product’s own name. More on light: does red light therapy work?
Your next step
- If you try itMinoxidil on the scalp — the over-the-counter, FDA-approved treatmentPooled placebo-controlled trials found it regrows hair in men and women. Give it 3–6 months; it stops working if you stop.
- If you try itA laser cap or comb with its own FDA clearancePooled trials against placebo devices found more hair density. Check the clearance is for that exact device.
- Test firstSee a dermatologist if it is sudden, patchy or itchyThose are different conditions with different treatments — and finasteride, for men, needs a prescription conversation.