Does PRP Work for Hair Loss? What the Evidence Actually Shows

Androgenetic alopecia — male and female pattern hair loss — is the most common cause of chronic hair loss, and affects up to 80% of men by the age of 70 (Donnelly et al., 2024). The approved treatments for it show modest results, and that gap is why platelet-rich plasma (PRP) has become one of the most heavily marketed hair-loss treatments in the US. This guide covers androgenetic alopecia — male and female pattern hair loss — and sticks to what three peer-reviewed reviews actually found.

This is information, not medical advice. See a physician before starting treatment.

The short version

Three systematic reviews report that PRP more often than not increases hair density compared with no treatment. One of them pooled a numeric estimate; the others didn't. The studies behind all three are small, inconsistent with each other, and don't follow patients long enough to say whether any benefit lasts.

How PRP works

A tube of your own blood is drawn, spun in a centrifuge to concentrate platelets, and the resulting plasma is injected into the scalp. Platelets carry growth factors, and the working idea is that these signal shrinking follicles back toward a growth phase.

Nothing is added from a donor or a laboratory. That makes PRP different from the stem cell and exosome treatments often advertised alongside it: PRP is not a stem cell therapy, and the two shouldn't be judged by the same evidence (PRP vs. stem cell therapy).

What the evidence shows

• Donnelly et al., 2024 (PubMed) pooled 8 trials and 1 cohort study, 291 men with male pattern hair loss. Six of nine studies found a significant density increase, five found a significant hair-count increase. The authors call this "some potential to be used therapeutically," limited by low-quality evidence and inconsistent results across studies. Seven of the nine studies carried a moderate risk of bias; two were rated low. This review only studied men.
• Lopes-Silva et al., 2025 (PMC) pooled 11 studies, 684 people (514 men, 170 women). Conclusion: PRP is "a viable therapeutic option... particularly for increasing hair density and thickness," though results vary with preparation method. This review included women but didn't report results separately by sex, so it doesn't tell us whether the effect is the same for both.
• Kieling et al., 2024 (PubMed) reviewed 14 studies covering 431 people, with 13 of those studies included in the pooled meta-analysis, which calculated an actual number: an average density gain of about 28 hairs per cm² (95% CI: 14 to 41). Take that number with real caution — the studies going into it disagreed with each other enormously (a heterogeneity measure of 96%, near the maximum possible), the authors rate the evidence low-quality, and they report clear signs of publication bias, meaning studies with disappointing results are less likely to have been published at all. A hair-thickness measure in the same analysis showed no significant effect. This is the closest thing to a number in this literature — not a number to expect on yourself.

The three reviews above don't establish how long any benefit lasts, or what maintenance schedule is needed to keep it — that isn't something they were designed to measure.

Why the studies disagree: there is no standard protocol

This is the single most useful thing to understand before you book anything. There's no single "PRP." The studies in the Lopes-Silva review differ in nearly every variable that could plausibly matter (Lopes-Silva et al., 2025):

• how the blood is spun, and the resulting platelet concentration
• whether the platelets are activated before injection
• how it's delivered — microneedling versus point-by-point injection
• how often it's given — some studies used three to six monthly sessions, others treated every two weeks
• how long patients were followed afterwards

The authors put it plainly: the "lack of standardization in PRP preparation protocols confounds the comparison of results across studies." That's also likely why Kieling's pooled estimate came out so inconsistent.

The practical consequence: two clinics can both truthfully say they offer PRP for hair loss and be doing measurably different things. Evidence that one protocol worked in a trial doesn't automatically transfer to a different protocol down the road. Sample sizes are also small across all three reviews (291-684 people, and much smaller per individual trial), which makes any single result easy to overstate.

By comparison: finasteride's FDA label restricts its approval to men — a 12-month trial in women is reported in that same label as not outperforming a placebo. Minoxidil is marketed over the counter in separate FDA-recognized formulations for men and for women.

Is PRP FDA-approved for hair loss?

How PRP is regulated is more involved than a yes or no, and we cover it — with the FDA's own documents — in Is PRP FDA-approved?. One thing is simple: if a clinic tells you an exosome hair treatment is FDA-approved, it isn't. The FDA states that there are currently no FDA-approved exosome products (FDA; see also our exosome guide).

What this means for treatment

PRP doesn't stop the genetic process behind androgenetic alopecia. The reviews cited here don't establish a standard maintenance schedule or how long treatment should continue — ask your provider what their recommendation is based on.

Reported side effects in this literature are mostly at the injection site: discomfort, swelling, redness, and temporary tenderness. We're not stating a conclusion about rarer or more serious risks — ask your provider about their own complication history directly.

Pricing and insurance coverage vary by provider and plan — ask directly rather than assuming. See what PRP costs, and why the price varies for what to ask.

Who's a reasonable candidate

People with early to moderate hair loss, where follicles are shrinking but still present, are the ones most likely to see something. PRP can't regrow hair where follicles are already gone.

The evidence for women is thinner and less separately analyzed than for men: the largest review with women in it (Lopes-Silva) didn't break out results by sex, and the male-only Donnelly review says nothing about women at all. That's a real gap in what's been studied, not evidence that PRP doesn't work for women.

PRP is often used alongside minoxidil or finasteride rather than replacing them — a reasonable add-on for someone who has plateaued on those, not a substitute for starting with them.

You can browse PRP hair-restoration providers by city. A listing shows a CMS registry number (NPI) when one is on file for the practice — which may be registered to the practice itself or to an individual. When a listing has a clinician roster, it shows each clinician's NPI-match status separately. A match confirms registration, not an active license or the quality of care.

Questions worth asking before you pay

• What system do you use, and what platelet concentration does it produce?
• Do you activate the platelets before injecting?
• Do you inject directly, or use microneedling?
• How many sessions, what schedule, and what's that based on?
• What will you measure — photographs, trichoscopy, hair counts — and when?
• What's your definition of "not working," and what happens then?
• What am I paying for year one and year two, all in?

A provider who can answer these specifically is describing a protocol. One who can't is describing a product.

Bottom line

The evidence leans positive but is genuinely inconsistent, low-quality by the reviews' own grading, and hasn't been checked for durability. One meta-analysis puts a number on the average effect — treat it as a rough signal, not a guarantee. If you're told a specific, precise result, or that it works the same for women as for men, that goes beyond what these three reviews support.