"Eyebrow growth serum" draws about 18,000 US searches a month, down by about half on a year earlier (clickstream estimate, October 2026). The products sold under the phrase borrow most of their claims from eyelashes, where one drug has an approval. Brows have their own, smaller record, and it contains a result that should frame every brow claim: in the largest eyebrow trial ever run, 43% of people improved on a liquid with no active ingredient. This page sets out that record as of 17 October 2026. It does not recommend any product; anyone with brow loss, especially sudden or patchy loss, should see a dermatologist.
The largest brow trial: bimatoprost against its own vehicle
Allergan, maker of the lash drug LATISSE, ran a phase 3 trial of bimatoprost 0.03% on the eyebrows (NCT01765764; published as Carruthers 2016, PMID 27124878). It randomized 357 adults with sparse brows, double-masked, to three arms for seven months. The results are posted on ClinicalTrials.gov:
| Arm | People | ≥1-grade fuller brows at month 7 | Change in brow area (photo analysis) | "Very" or "mostly" satisfied |
|---|---|---|---|---|
| Bimatoprost twice daily | 118 | 83.9% | +34.5 mm² | 70.3% |
| Bimatoprost once daily (vehicle in the morning) | 118 | 77.1% | +31.0 mm² | 52.5% |
| Vehicle twice daily | 121 | 43.0% | +6.4 mm² | 36.4% |
Brow area at the start was about 100 mm², so the drug arms added roughly a third (our arithmetic from the posted means) and the vehicle about 6%. Brows also darkened slightly on the drug and not on the vehicle. Adverse events were reported in 38.1%, 42.4% and 35.5% of the three groups, and the paper reports no skin or iris darkening and no eye redness. The paper's author affiliations include Allergan and a medical-communications firm.
The trial finished in early 2014 (primary completion January, study completion February). LATISSE's label, read on 17 October 2026, is still indicated for "hypotrichosis of the eyelashes" alone, and an openFDA search of drug-label indications mentioning eyebrows returned 16 listings — castor oils, a brow tint, a homeopathic alopecia product, two brow serums and a few skincare items — none of them carrying an FDA application number, the mark of an approved drug. Whatever happened between the trial and a label is not on the public record; what is on record is that no drug is FDA-approved to grow eyebrows.
The 43% problem
The vehicle result is the most useful number on this page for anyone reading brow marketing. Four in ten people using a solution with no drug in it were graded as having fuller brows after seven months, by physicians who did not know which arm they were in. The trial does not say why. Daily attention, a pause in plucking or threading for the study, natural variation in brow hair and the difficulty of rating against a remembered baseline are all plausible, and none is measured. The consequence is the same: a brow serum's before-and-after photographs, a satisfaction survey or a trial without a vehicle arm cannot distinguish the product from that background. Only the gap between product and vehicle — here, about 6 mm² against 31–35 mm² — shows an effect.
The smaller brow trials
A PubMed search for bimatoprost with eyebrow terms returned 18 records on 17 October 2026. The controlled trials among them:
| Trial | People | Comparison | Reported |
|---|---|---|---|
| Beer 2013, US (PMID 23617229) | 20 | Bimatoprost 0.03% vs vehicle, then re-randomized | Investigator scores improved on bimatoprost at months 6 and 7; not on vehicle; no adverse effects |
| Suwanchatchai 2012, Thailand (PMID 22594928) | not in the record | Bimatoprost 0.03% vs minoxidil 3%, split-face | Published as a short letter |
| Suchonwanit 2019, Thailand (PMID 30913051) | 40 | Bimatoprost 0.01% vs vehicle, 6 months | Density, hair diameter and clinical scores higher on drug |
| Suchonwanit 2020, Thailand (PMID 31317662) | 30 | Bimatoprost 0.01% on one brow, 0.03% on the other | Both raised density and diameter, with no significant difference between them; patients preferred the 0.03% side |
| Zaky 2023, Egypt (PMID 37517060) | 60 | Bimatoprost 0.03% vs 0.01% vs minoxidil 2% gels | All improved; no significant difference between the three |
One further phase 4 study, of 33 people (NCT01891487), is registered with no results posted. Every one of these trials tested a drug, not a cosmetic serum.
Where peptide brow serums stand
Many brow serums sold in shops list peptides rather than a prostaglandin — myristoyl pentapeptide-17, biotinoyl tripeptide-1 and similar. A PubMed search for peptides combined with eyebrow growth, serum or hypotrichosis returned two records on 17 October 2026: one on a genetic condition and one on an acupuncture-style diagnostic test. Neither concerns growing brows. There is no published brow trial of a peptide serum, controlled or otherwise. The laboratory and lash evidence for those peptides, which is thin in its own right, is set out in our analysis of The Ordinary's Multi-Peptide Lash and Brow Serum; how to tell from an ingredient list whether a serum contains a prostaglandin is covered in our comparison of prostaglandin and peptide lash serums.
That page also records the safety question for the cosmetic prostaglandin analogues — isopropyl cloprostenate and its relatives — which Europe's Scientific Committee on Consumer Safety concluded in February 2026 could not be considered safe in lash and brow products. The licensed drug carries its own label warnings: darkening of eyelid skin, and darkening of the iris that is likely to be permanent.
What is not established
Whether any peptide grows eyebrow hair in people; whether cosmetic prostaglandin analogues match bimatoprost's brow result at their lower concentrations; how long brow gains last after stopping; and why the vehicle arm in the largest trial did so well. Brow loss can also be a sign of thyroid disease, alopecia areata or other conditions — a reason to see a dermatologist rather than a serum shelf. Scalp-hair evidence for peptides, a separate question, is on our page about peptides for hair growth.
Sources
Opened 17 October 2026: ClinicalTrials.gov record NCT01765764 with posted results (arms, primary and secondary outcomes, adverse-event groups) and the bimatoprost-eyebrow registry search (six records); LATISSE label via openFDA (effective July 2024) and an openFDA search of label indications for eyebrows; PubMed records 27124878, 23617229, 22594928, 30913051, 31317662 and 37517060, the search bimatoprost[tiab] AND (eyebrow*[tiab] OR brow[tiab] OR brows[tiab]) (18) and the peptide-eyebrow search (2). Corrections go to the contact page.