Microneedling Hair Growth: What Studies Measured
Studies of microneedling for hair measure things you can count: hairs in a marked patch, hair density, hair width and ratings by doctors and patients. What they found depends on who took part, what else they used and how long it lasted.
How hair growth is measured
- Hair count. Hairs in a small marked area. In the 2013 pilot the scalp was shaved so all hairs had the same length, and the counting patch was marked with a tattoo.
- Hair density. Hairs per square centimeter, the measure used in the 2023 network meta-analysis at 24 weeks.
- Hair diameter. How thick each hair is. In the 2023 meta-analysis, thickness did not change significantly even where counts did.
- Ratings. Doctors or patients score photos on a scale. The 2013 pilot used a 7-point scale. Scales differ between trials.
Evidence labelsRandomized trialPooled analysisPilot or small studyExpert review
| Study | Who took part | What was measured | Limits |
|---|---|---|---|
| Randomized trial, 2026 Randomized trial | 245 women with mild to moderate pattern hair loss. | Non-vellus hair count in a target area after 24 weeks. Compared minoxidil alone, plus monthly microneedling and plus microneedling every 2 weeks (36-needle cartridge, 500 to 550 µm). | No added benefit from microneedling. Single center, open label, no patient-reported outcomes. |
| Randomized pilot, 2013 Pilot or small study | 100 men with early to moderate pattern hair loss. | Hairs in a marked 1 cm² patch at 12 weeks, plus doctor and patient ratings. Weekly microneedling plus a drug lotion beat the lotion alone (91.4 vs 22.2 hairs on average). | Pilot design, 12 weeks, men only. Evaluators were blinded, which the abstract does not say of participants. |
| Meta-analysis, 2023 Pooled analysis | Ten randomized trials reviewed (466 patients), eight pooled. | Total hair count and hair diameter. The count favored microneedling plus minoxidil (standardized mean difference 1.76). Diameter did not reach significance. | The authors note that rating scales, needling methods and treated areas differed and may have confounded the result. |
| Meta-analysis, 2024 Pooled analysis | 13 randomized trials, 696 people. | Combined microneedling therapy against single treatments. Hair density and diameter favored the combination. Doctor ratings were higher, while patient ratings did not differ significantly. Adverse events did not differ. | Pools trials that used different partner treatments. |
| Network meta-analysis, 2023 Pooled analysis | 27 trials, 1,110 adults with pattern hair loss. | Change in total hair density at 24 weeks. Minoxidil plus microneedling ranked highest. Microneedling alone ranked below minoxidil alone. | Indirect comparisons across trials, not head-to-head tests. |
| Systematic review, 2022 Pooled analysis | 22 studies, 1,127 people, several types of hair loss, needle depths 0.5 to 2.5 mm. | Hair measures when microneedling was added to other treatments. No serious adverse events among 657 people who received it. | Quality scores were low (Jadad 1 to 3). The authors call for large randomized trials and long-term safety data. |
| Expert review, 2018 Expert review | Published studies on microneedling and hair loss. | Summary of microneedling for hair loss. It says the evidence does not allow a claim that microneedling beats standard therapies, and calls for a standard protocol. | A narrative review, not a new analysis. |
Why results vary so much
- Different partner treatments. Most studies pair microneedling with a drug or another product, so the effect of the needling alone is hard to isolate.
- Different protocols. The 2022 review reports depths from 0.5 to 2.5 mm and sessions from weekly to monthly. No standard protocol exists.
- Different people. Men, women, early and later stages, and several kinds of hair loss appear across the literature.
- Different designs. Pilot studies, open-label trials and blinded trials sit side by side in reviews.
- Short follow-up. The two trials above measured at 12 and 24 weeks.
A calendar for 12 months
This is a planning aid, not a forecast. It marks where the evidence ends.
- Before the first session
Diagnosis by a dermatologist. Baseline photos in one spot, one light, one parting. Write down the date and the plan for review.
- Month 1
Sessions happen as your clinician schedules them. Skin effects such as redness or tightness typically fade within days or weeks, the FDA says.
- Month 3
Matches the 2013 pilot, which counted hairs at 12 weeks. Take the same photos. Judge nothing yet; this is a checkpoint.
- Month 6
Matches the 24-week trial and the network meta-analysis. If photos and counts show no change, ask whether to continue and what else might be going on.
- Month 12
No trial above reports this far. Compare with month 0 and decide with your clinician. Whether changes last is not established.
What no study can tell you
Averages hide individuals. A study can say that a group gained or did not gain hair. It cannot say what will happen to your scalp. It also cannot replace a diagnosis, because hair loss has many causes and some need a different kind of care.
For what a clinic session involves, read scalp microneedling in a clinic. For the home route, see doing it at home.
Questions about the numbers
How many hairs did people gain in the studies?
It depends on the study. In the 2013 pilot, the average change after 12 weeks was 91.4 hairs in a marked 1 cm² patch with microneedling plus a drug lotion and 22.2 with the lotion alone. In the 2026 trial of women, every group gained hair and the groups did not differ significantly. Numbers from different studies are not directly comparable.
Why do some studies look better than others?
Size, design and who took part all matter. Small pilots tend to report larger effects than bigger trials. Open-label designs, where everyone knows who had which treatment, leave more room for bias. Reviews also note that devices, depths and schedules differ from study to study.
Will I get results like the studies?
No study can say that about one person. Studies report averages for a group, and individuals vary. A dermatologist who knows the cause of your hair loss is the right person to ask what to expect.
Sources
- 2026 randomized trial, PubMed. 245 women, 24 weeks, three groups. Hair counts rose in every group with no significant difference between them. PMID 42190753.
- 2013 randomized pilot study, PubMed. 100 men with early to moderate pattern hair loss, 12 weeks. Weekly microneedling plus a drug lotion compared with the lotion alone. PMID 23960389.
- 2023 meta-analysis, PubMed. Ten randomized trials reviewed (466 patients), eight pooled. PMID 37665358.
- 2024 meta-analysis, PubMed. Thirteen randomized trials, 696 people, combined microneedling therapy compared with single treatments. PMID 38239003.
- 2023 network meta-analysis, PubMed. 27 trials, 1,110 adults, change in hair density at 24 weeks. PMID 38058547.
- 2022 systematic review, PubMed. 22 clinical studies, 1,127 people, searched through November 2021. PMID 34854067.
- 2018 expert review, PubMed. Narrative review of microneedling for hair loss. PMID 29194786.
Want to talk to a clinic?
Hair loss has many causes. If you want a clinic opinion, you can join the waitlist for a verified clinic near you.