Skip to content
AlternativeMed

SPECIALTY TOPICS · GUIDE

Platelet-Rich Plasma: What Trials Show by Condition

Platelet-rich plasma (PRP) evidence condition by condition, from knee, ankle and tendon problems to hair loss and wounds, with trial results, mixed findings and US regulatory status.

Content last updated . This page has not been medically reviewed.

Back to Emerging Wellness Science
Quick answer
PRP is plasma from a person's own blood that has more platelets than normal blood. Whether it helps depends on the condition, and on how the PRP was made. Large well-controlled trials found no benefit for ankle arthritis and Achilles tendon pain, while knee arthritis and hair loss show mixed or limited results. This page is information only, not medical advice, and it gives no preparation or injection instructions.

What PRP is, and why products differ

Strictly, PRP is plasma enriched in platelets compared with the person's own blood. Platelet count, white blood cell content and activation methods vary, which makes standardization hard and makes one trial's PRP different from another's. [1] That is why results for one preparation do not automatically apply to another.

Evidence labels used here

Approved medicine: a regulator approved it for a stated use. Promising but limited: some positive human data with weaknesses. Mixed: trials disagree. No good evidence of benefit: high-quality trials found no difference from placebo. We explain all labels in how we label evidence.

Evidence by condition

7 findings · 1 supported · 2 mixed · 4 limited or unclearThe colour follows the evidence label on each card.

  1. Knee osteoarthritis

    Mixed

    Mixed (details below)

  2. Ankle osteoarthritis

    No good evidence of benefit

    No difference from placebo at 26 weeks [2]

  3. Chronic Achilles tendinopathy

    No good evidence of benefit

    No difference from sham at 6 months [3]

  4. Tennis elbow (lateral epicondylitis)

    Mixed

    Compared with steroid injection, not placebo (details below)

  5. Rotator cuff repair surgery

    No good evidence of benefit

    No difference in retear rate in 8 trials [4]

  6. Pattern hair loss

    Promising but limited

    Some hair-density gain over placebo, other measures not different [5]

  7. Chronic wounds

    Insufficient evidence

    Unclear overall; low-quality evidence for diabetic foot ulcers [6]

Knee osteoarthritis in detail

The RESTORE trial randomized 288 adults aged 50 or older with mild to moderate knee osteoarthritis to three weekly PRP injections or saline placebo. At 12 months the pain change was -2.1 vs -1.8 points (difference -0.4, 95% CI -0.9 to 0.2), and 29 of 31 secondary outcomes showed no difference. [7] A 2025 meta-analysis of 18 placebo-controlled trials (1,995 patients) reported statistically better pain and function scores, with clinically meaningful pain relief at 3 and 6 months, and larger effects with higher-platelet PRP. [8] A separate 2025 meta-analysis found PRP better than hyaluronic acid injections at 12 months. [9] The trials disagree, and preparation differences are one possible reason. A single large trial and a pooled analysis of many smaller ones can both be correct about what they measured.

Tendon and elbow problems

In the Achilles trial, 240 adults with long-lasting tendon pain received one PRP injection or a sham needle. The 6-month score difference was -2.7 points (95% CI -8.8 to 3.3), and injection-site discomfort was the most common adverse event. [3] A 2025 meta-analysis of six trials (422 patients) found no benefit and suggested publication bias may have overstated benefit. [10] For tennis elbow, a 2024 meta-analysis of 11 trials (730 patients) found PRP worse than steroid injections at under two months but better at six months or longer. [11] Because the comparator was steroid and not placebo, it does not show PRP beats no treatment.

Hair and wounds

A 2023 meta-analysis of nine randomized trials (238 patients) found PRP increased hair density at 3 and 6 months versus placebo, but hair count and diameter did not differ from placebo. Adverse reactions were reported in two of seven studies. [5] For chronic wounds, a Cochrane review found it unclear whether PRP improves healing generally, and PRP may help diabetic foot ulcers, based on low-quality evidence from two small trials. [6] See also pattern hair loss.

Related guides

Frequently asked questions

Does PRP work for knee arthritis?

Results are mixed. A 288-person placebo-controlled trial found no significant difference at 12 months, while a meta-analysis of 18 trials favored PRP. [7] [8]

Does PRP help Achilles tendon pain?

A 240-person trial and a meta-analysis of six trials found no benefit over placebo or sham. [3] [10]

Is PRP FDA-approved?

PRP preparation devices are cleared under 510(k), mostly for bone graft handling, and injection use is off label. [12]

Is PRP the same as stem cell treatment?

No. PRP is plasma enriched in platelets, and it is a different kind of product from stem-cell preparations. [1] See PRP vs cell-based treatments.

Is PRP proven for hair loss?

Evidence is promising but limited: hair density improved in some trials, other measures did not differ from placebo. [5]

More details: evidence, limits and cautions

The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.

Regulation (United States)
PRP preparation systems reach the US market through the FDA 510(k) pathway, and a 2015 review reported nearly all were cleared for making platelet-rich preparations to mix with bone graft materials. Office injection use outside that setting is "off label." [12] A 2024 FDA clearance record shows the same pattern, a "Platelet And Plasma Separator For Bone Graft Handling." [13] Clearance of a preparation device does not show that PRP injections work for a condition. The review is dated, so current labeling should be checked. Other countries regulate differently, and I did not verify them. See off-label use explained.
Risks and who should check first
In the trials, injection-site discomfort, swelling and bruising were common in both PRP and sham groups. [3] Rarer risks such as infection are not quantified in the sources I read. Anyone with a bleeding disorder, who takes blood thinners, or who has an active infection or cancer should ask their own clinician first.
References
  1. PRP or not PRP: Is the debate surrounding platelets-based blood-derived products evolving? Knee Surg Sports Traumatol Arthrosc 2025. PubMed 40079361. Read 2026-10-22.
  2. Effect of PRP injections vs placebo on ankle osteoarthritis: randomized clinical trial. JAMA 2021. PubMed 34698782. Read 2026-10-22.
  3. Effect of PRP injection vs sham injection on chronic midportion Achilles tendinopathy: randomized clinical trial. JAMA 2021. PubMed 34255009. Read 2026-10-22.
  4. PRP in arthroscopic rotator cuff repair: meta-analysis of randomized controlled trials. Arthroscopy 2015. PubMed 25278352. Read 2026-10-22.
  5. PRP for Androgenetic Alopecia: Systematic Review and Meta-Analysis of RCTs. J Cutan Med Surg 2023. PubMed 37533146. Read 2026-10-22.
  6. Autologous platelet-rich plasma for treating chronic wounds. Cochrane Database Syst Rev 2016. PubMed 27223580. Read 2026-10-22.
  7. Bennell KL, et al. RESTORE: PRP vs placebo for knee osteoarthritis. JAMA 2021. PubMed 34812863. Read 2026-10-22.
  8. PRP Injections for Knee Osteoarthritis: meta-analysis of randomized controlled trials. Am J Sports Med 2025. PubMed 39751394. Read 2026-10-22.
  9. PRP vs hyaluronic acid for knee osteoarthritis: meta-analysis of double-blinded trials. Arthroscopy 2025. PubMed 40681006. Read 2026-10-22.
  10. Is PRP Effective in Treating Achilles Tendinopathy? Meta-analysis of randomized trials. Clin Orthop Relat Res 2025. PubMed 39745256. Read 2026-10-22.
  11. PRP vs corticosteroid for lateral epicondylitis: meta-analysis of randomized trials. Am J Sports Med 2024. PubMed 38357713. Read 2026-10-22.
  12. US definitions, current use, and FDA stance on use of platelet-rich plasma in sports medicine. J Knee Surg 2015. PubMed 25268794. Read 2026-10-22.
  13. U.S. Food and Drug Administration. BK241083 - Platelet And Plasma Separator For Bone Graft Handling (510(k) record). Read 2026-10-22.
Education, not medical advice. This page is for general information. It does not diagnose or treat any condition and is not a substitute for care from a qualified health professional. Natural does not automatically mean safe. Ask a clinician or pharmacist before changing your care, especially if you take medication, are pregnant or breastfeeding, or have a health condition.