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PRF is a family of preparations, and the spin decides which one you get

The name covers several products. A 2009 classification in Trends in Biotechnology sorted platelet concentrates into 4 categories by their leukocyte and fibrin content. Two of the four are fibrin-based: pure platelet-rich fibrin, and leukocyte- and platelet-rich fibrin. Choukroun’s original PRF, developed in dentistry in 2001, is the leukocyte-rich one.

Injectable PRF came later and does not appear in that taxonomy at all. It comes out of the low-speed centrifugation concept, which found that dropping the relative centrifugal force raises the platelets and leukocytes ending up in the final product. In the paper introducing the concept, spinning at 44 g produced significantly more of both than 177 g or 710 g.

Published protocols from 10 mL of whole blood run like this. L-PRF spins at 2,700 rpm, 708 g, for 12 minutes. A-PRF at 1,500 rpm, 208 g, for 14 minutes. A-PRF+ at 1,300 rpm, 200 g, for 8 minutes. Injectable PRF sits at the far end, 700 rpm, 60 g, for 3 minutes.

One caution about those numbers. G-force depends on rotor radius, so an rpm figure from one centrifuge does not transfer to another. Which is why a 2024 review of PRF in androgenetic alopecia, co-authored by hair specialist Jeff Donovan, concluded that “there is no consensus regarding the preparation of PRF.” Of 5 studies analyzing spin parameters, 3 favored low speed and 2 did not.

The tube matters too, and almost nobody mentions it. Plain glass tubes activate Factor XII and start clotting with no chemical additive. Silica-coated plastic tubes have been reported to produce smaller, silica-contaminated clots. Silicone-coated tubes have been linked to inflammatory response and delayed clot formation. Titanium-activated tubes produce a firmer fibrin network with a longer resorption time.

PRF uses no anticoagulant at all. No acid-citrate-dextrose, no sodium citrate, nothing added to the tube. That absence is the whole reason the fibrin network forms.

What the PRF trials actually found

The strongest evidence for PRF in hair loss is a single randomized trial in women, and it found injectable PRF raised hair count by roughly a quarter over 24 weeks with the lowest adverse event rate of the treatments tested. Everything else is smaller and weaker.

The randomized trial

A prospective multicenter randomized clinical trial published in the Journal of Dermatological Treatment in 2026 ran injectable PRF against two comparator preparations in female pattern hair loss, Sinclair grade II to III. Patients received 4 sessions at 4-week intervals. 74 completed. At 24 weeks, target area hair count in the i-PRF group rose 26.54%, against 14.53% in the weakest arm, a statistically significant difference. The i-PRF group had the lowest adverse event rate of the three.

Read the limits with the result. Women only. One trial. And the concentrated growth factor arm reached 27.11% with no significant difference from i-PRF, so this is not evidence that PRF is the best available option.

The refractory series

A prospective single-center study in Archives of Dermatological Research gave 6 monthly i-PRF injections to 30 patients whose response to conventional treatment had been inadequate, reporting an 80% response rate at 6 months with better quality-of-life scores and minimal adverse reactions. Single-arm, no control, no randomization, and the abstract never defines what counted as a response. The number worth taking from it is 6, not 80. Those patients got six monthly injections, denser than the 3-to-4-session course usually sold.

The women's case series

An 11-patient series in the Journal of Cosmetic and Laser Therapy used 3 sessions by mesotherapy gun, 27 gauge, 1.5 to 2.5 mm depth, roughly 4 mL per session. Follicular density went from 0.57 to 0.89 follicles per square millimeter at week 12 and 1.03 at week 24. Pull tests turned negative in all 11. The authors named their own limits: 11 patients, no control group, 6 months, and a narrow population of non-smoking women at Ludwig I to II.

Where it thins out. A 2026 systematic review covering PRF alongside 4 other regenerative treatments described PRF as producing “the fastest and most consistent responses.” Its PRF evidence base was 4 prospective studies, 204 participants, none randomized. The 2014 cohort reporting the largest density gains found its 6-month result was no longer statistically significant. And a 15-case series from 2022 had every patient on minoxidil and finasteride at the same time, so nothing in it can be attributed to PRF.

That is the state of the evidence. One randomized trial in 74 women, a few small single-arm studies, and a preparation the field cannot agree how to make.

The 10-day claim, and where it comes from

PRF releases growth factors gradually rather than all at once. The primary source is a 2016 laboratory study in Clinical Oral Investigations that measured release across platelet preparations using 18 blood samples from 6 donors, sampling at 15 minutes, 60 minutes, 8 hours, 1 day, 3 days and 10 days.

What it found: PRF “displayed a continual and steady release of growth factors over a 10-day period,” and at the later time points advanced PRF released the highest total growth factors of anything tested. The authors concluded advanced PRF is the better choice where sustained release is the goal.

Two things follow. 10 days is the ceiling of what was measured, not of what happens. The study stopped there. Any page claiming 14 days is quoting past its own evidence. And this was a lab study of release kinetics, not a hair outcome study. Release speed is a mechanism, not a result.

The growth factors quantified in that work were PDGF-AA, PDGF-AB, PDGF-BB, TGF-β1, VEGF, EGF and IGF, with PDGF-AA released in the highest quantity.

Woman learning about PRF hair restoration with a medical provider

Real Patient Results

Microneedling + PRF + Exosomes — After 2 Sessions

Results vary by individual and treatment plan

Who should not have PRF

No FDA-approved label exists for PRF in hair loss, so there is no regulatory contraindication list. What follows comes from published dermatology reviews. It is expert opinion, and the sources disagree on some numbers, which is itself worth knowing.

Reasons we would not treat you at all: platelet dysfunction disorders, active infection at the injection site, sepsis, and hemodynamic instability.

Reasons we would delay or reconsider: a platelet count under 150,000 per microlitre, hemoglobin under 10 g/dL, NSAIDs within 48 hours of treatment, a corticosteroid injection at the site within the past month or systemic corticosteroids within the past 2 weeks, malignancy, tobacco use, and recent fever or illness.

Commonly listed elsewhere, not actually established. Pregnancy, breastfeeding, and anticoagulant or antiplatelet therapy do not appear in the contraindication lists of the two published reviews we worked from. We screen for all three anyway, because conservative practice with a blood-derived product is reasonable. We are not going to tell you the literature says something it does not.

Scarring alopecia. If the scalp is smooth and shiny with no follicular openings, the follicle is gone and nothing injected into it brings it back. For diagnosed cicatricial alopecias, the AAD’s position is that evidence for platelet therapy “is still at the case report and case series level.” That is not a reason to buy a series.

Side effects. The AAD reports that the most common side effects of scalp platelet therapy are immediate and self-resolve within 24 hours, listing pain, swelling, bleeding, lightheadedness or low blood pressure, and redness, with pain most commonly reported. In the PRF trials specifically, adverse events were consistently described as mild and transient, and the randomized trial found the PRF arm had the lowest rate of the three treatments compared.

Who draws the blood, and who does the injection

Florida does not license phlebotomists. The statute that defines clinical laboratory personnel, section 483.803(4), specifically excludes them. So drawing your blood is a delegated medical act rather than a licensed occupation, and the question is not “is this person a phlebotomist” but “who is responsible for them.”

Under section 458.3485, a medical assistant may perform venipuncture and non-intravenous injections, but only under the direct supervision and responsibility of a licensed physician. Physician assistants work under section 458.347, performing services delegated by a supervising physician within their education and training. Supervision there means “the easy availability or physical presence” of the physician, so a PA injecting without a physician standing in the room is lawful, provided the supervisory relationship is real.

Man undergoing scalp preparation before a PRF hair procedure

The Florida Board of Medicine drew this line in a hair restoration case. In a 2016 declaratory statement, a physician asked whether medical assistants could harvest follicles and create recipient site incisions under his direct supervision. The Board said no, holding that “the performance of surgical procedures is not included in the list of clinical procedures unlicensed medical assistants are permitted to perform.” Injections and blood draws sit on the permitted side. Surgical excision does not.

Ask any clinic 2 questions: who draws the blood and under whose license, and who performs the injection. A clinic that cannot answer clearly has a delegation problem, and delegating to someone unqualified is itself grounds for discipline under section 458.331(1)(w).

Frequently Asked Questions

Is PRF for hair loss FDA approved?

No. In the United States it is off-label use of your own blood. The AAD states that platelet devices have not been cleared by the FDA for alopecia. The clearance covers the equipment, not the use.

Why does the spin protocol matter so much?

Because it decides what ends up in the tube. Lowering the centrifugal force raises the platelets and leukocytes in the final preparation, and published protocols run from 708 g for 12 minutes down to 60 g for 3 minutes. A 2024 review found no consensus on which setting is right. Ask which one your clinic runs, and what preparation it produces.

Is PRF injected into the scalp or applied on top after microneedling?

Both are offered across the industry, and only one has been studied. Every published clinical trial of PRF for hair loss injected it. Topical application over microneedling has not been tested in a published hair trial. Ask which route your clinic uses before you compare it against any study.

How many sessions does the research use?

The randomized trial used 4 sessions at 4-week intervals. The study in patients who had already failed conventional treatment used 6 monthly injections. The case series in women used 3. No single protocol is established, and the reviews say so.

When would I see a change?

The published trials measured at 12 and 24 weeks. Nothing visible happens in the first few weeks. Any clinic promising a change sooner is describing a hope.

How strong is the evidence for PRF?

Thinner than the marketing suggests. One randomized multicenter trial in 74 women, a 30-patient uncontrolled series, an 11-patient case series, and a 2014 cohort whose 6-month result lost statistical significance. A 2024 review concluded larger, well-designed studies are still needed. That is a reason to consider PRF, not to call it settled.

Will it work on a bald patch?

No. Where there is no follicle left, there is nothing for a growth factor to act on. This is the most common reason a course of treatment produces nothing at all.

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  • Woman discussing PRF options for hair loss with a clinician