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Research · Therapies

PRP injections

Against saline placebo, PRP did not ease tennis elbow, Achilles tendinopathy or 12-month knee osteoarthritis pain in the largest trials, though pooled knee trials found less pain to 6 months. Added to rotator cuff repair, it lowered retear rates. In hair loss it raised hair density against placebo. Injection reactions were more common than with saline in knee trials.

Checked 2026-11-13
Status
PRP is made from a person's own blood and falls under the FDA's Center for Biologics Evaluation and Research, which exempts it from the usual drug approval pathway. Most PRP preparation systems are cleared through the 510(k) device pathway for mixing with bone graft material, so injecting PRP in an office for joints, tendons or hair is off-label use [1].
Also called
platelet-rich plasma, PRP, PRP injection, PRP therapy, platelet injection, autologous platelet-rich plasma, leukocyte-poor PRP, leukocyte-rich PRP, PRP hair treatment, PRP for hair loss, vampire facial, autologous conditioned plasma, ACP
Used for
knee osteoarthritis, knee pain, joint pain, tennis elbow, Achilles tendinopathy, rotator cuff tears, shoulder pain, tendon injuries, sports injuries, faster healing, hair loss, hair regrowth, androgenetic alopecia, skin rejuvenation

Strong several reviews agree · Moderate one review or consistent trials · Limited one or a few small studies · Untested no study in people, listed with what it rests on

Shown to help3

Reported risks2

What it is used for, and what was found

Shown to help3

Moderate

Knee osteoarthritis, compared with hyaluronic acid

Shown in pooled trials to give better knee pain, function and WOMAC scores after injection than hyaluronic acid injections.

Compared with hyaluronic acid injections [5]

The numbers and sources
Effect
Across 27 randomized trials, scores after injection were better with PRP than with hyaluronic acid for WOMAC (P < .001), pain on the visual analog scale (P < .01) and the Subjective IKDC knee score (P < .001) [5].
Population
1,042 patients given PRP and 1,128 given hyaluronic acid, mean age 57.7 and 59.0, mean follow-up about 14 months [5].
Sources
[5]
Caveats
Hyaluronic acid is an active injection, not a placebo. The abstract gives P values without effect sizes [5].
Moderate

Rotator cuff repair, added during surgery

Shown to lower repair failure after rotator cuff surgery, 15.9% against 29.0%, with function gains below the clinically important threshold.

Compared with rotator cuff repair without PRP [12]

The numbers and sources
Effect
Leukocyte-poor PRP injected during arthroscopic repair lowered repair failure to 34 of 213 (15.9%) from 63 of 217 (29.0%) (RR 0.55, 95% CI 0.38 to 0.79). Constant, UCLA and other function scores were higher at 6 to 24 months, by amounts below the minimal clinically important difference. Complications were 9.4% and 7.7% (P = .508) [12].
Population
470 patients in 5 randomized trials [12].
Sources
[12]
Caveats
Applies to PRP given during surgery, not to injections for tendon pain without surgery.
Moderate

Pattern hair loss, compared with placebo

Shown to raise hair density in androgenetic alopecia against placebo at 3 and 6 months. Hair count and hair diameter did not differ from placebo.

Compared with placebo [13]; control groups the review abstract does not describe [14]

The numbers and sources
Effect
Across 9 trials, PRP raised hair density at 3 and 6 months against placebo (P < .05). Hair count and diameter rose from baseline and did not differ from placebo [13]. In 21 trials in women with hair loss, PRP raised hair density and thickness and reduced hairs lost on the pull test, with pain or discomfort no different from control (RR 1.01, 95% CI 0.87 to 1.18) [14].
Population
238 patients with androgenetic alopecia in 9 trials [13]. 628 women in 21 trials [14].
Sources
[13], [14]
Caveats
Trials were small. The reviews give no pooled size for the density gain in their abstracts, and the women's review notes effects varied with dose, schedule and ethnicity [13][14].

Mixed results3

Moderate

Knee osteoarthritis, compared with saline placebo

Mixed results: pooled placebo-controlled trials found less knee pain up to 6 months, while the largest trial, of 288 people, found no difference from saline at 12 months.

Compared with saline placebo injections [2][3][4]

The numbers and sources
Effect
In 288 adults aged 50 or older, knee pain changed by -2.1 points with PRP and -1.8 with saline at 12 months (difference -0.4, 95% CI -0.9 to 0.2, on a 0 to 10 scale with a clinically important difference of 1.8). Cartilage volume did not differ, and 29 of 31 secondary outcomes did not differ [2]. Across 11 trials, pain was lower than placebo at 3 months (MD -1.1, 95% CI -1.8 to -0.4) and 6 months (MD -2.0, 95% CI -2.8 to -1.2), and not at 12 months. WOMAC scores improved at 3 months only [3]. A review of 20 placebo-controlled studies found better function and pain at 6 and 12 months, at very low certainty [4].
Population
288 adults with mild to moderate medial knee osteoarthritis in Australia [2]. 1,616 patients in 11 trials, mean age 56.9 [3]. 1,774 PRP and 1,518 placebo participants in 20 studies [4].
Sources
[2], [3], [4]
Caveats
Heterogeneity was high in the pooled pain results [3], and certainty very low [4]. The largest trial, blinded for participants, injectors and assessors, found no difference [2].
Moderate

Rotator cuff tendinopathy, injection

Mixed results: a pooled review reported short-term pain relief against placebo and corticosteroids, while a placebo-controlled trial found no difference from saline at one year.

Compared with placebo or corticosteroid injections [10]; saline injection, both groups exercising [11]

The numbers and sources
Effect
Across 30 randomized trials, PRP reduced pain and improved function in the short term against placebo and corticosteroids, with no greater benefit beyond 12 months [10]. In 40 patients, WORC, SPADI and pain scores did not differ from saline at any time point through one year (P = .174, .314 and .904 at one year), and both groups improved [11].
Population
About 2,500 participants in 30 trials [10]. 40 adults aged 18 to 70 with chronic rotator cuff tendinopathy [11].
Sources
[10], [11]
Caveats
The review abstract gives no effect sizes and does not separate placebo from corticosteroid comparisons [10].
Moderate

Pattern hair loss, compared with minoxidil

Mixed results: hair density, terminal hair count and regrowth did not differ from 5% minoxidil, while patient satisfaction was higher with PRP.

Compared with topical minoxidil [15]

The numbers and sources
Effect
Across 9 trials, hair density did not differ between PRP and minoxidil, and neither did terminal hair count or moderate to high regrowth. Patient satisfaction was higher with PRP than with 5% minoxidil (OR 2.77, 95% CI 1.53 to 5.04), and negative hair pull tests were more common, 82.75% against 52.94% [15].
Population
451 men and women with androgenetic alopecia in 9 trials [15].
Sources
[15]
Caveats
Heterogeneity across studies was high [15].

Not shown to help2

Moderate

Tennis elbow

Not shown to ease tennis elbow pain or function more than placebo injection at 3, 6 or 12 months, for PRP or whole-blood injections, in a Cochrane review.

Compared with placebo injection [6]

The numbers and sources
Effect
At 3 months, mean pain was 3.7 out of 10 with placebo and 0.16 points better with autologous blood or PRP (95% CI 0.60 better to 0.29 worse, 8 studies, 523 participants). Function was 1.86 points better on a 100-point scale (95% CI 4.9 better to 1.25 worse), and treatment success was 67% against 65% (RR 1.00, 95% CI 0.83 to 1.19). No clinically important benefit appeared at 6 or 12 months [6].
Population
32 trials with 2,337 people with lateral elbow pain, 10 of them placebo-controlled [6].
Sources
[6]
Caveats
Evidence was moderate in certainty, downgraded for bias [6].
Moderate

Achilles tendinopathy

Not shown to improve chronic Achilles tendinopathy more than a sham or saline injection, in three placebo-controlled trials through one year.

Compared with sham injection, a dry needle under the skin not entering the tendon [7]; saline injection, both groups doing eccentric exercises [8][9]

The numbers and sources
Effect
At 6 months, VISA-A scores were 54.4 with PRP and 53.4 with sham (adjusted difference -2.7, 95% CI -8.8 to 3.3, clinically important difference 12) [7]. With eccentric exercise, VISA-A improved 21.7 points with PRP and 20.5 with saline at 24 weeks (difference -0.9, 95% CI -12.4 to 10.6) [8]. At one year the difference was 5.5 points (95% CI -4.9 to 15.8), and 59% in both groups were satisfied [9].
Population
240 adults at 24 UK sites, mean age 52 [7]. 54 adults aged 18 to 70 in the Netherlands, followed for 24 weeks [8] and one year [9].
Sources
[7], [8], [9]
Caveats
The two smaller reports are the same trial at two time points [8][9].

Protocols studied

The largest knee trial gave 3 weekly injections of leukocyte-poor PRP from a commercial system [2]. The Achilles trials gave a single injection into the tendon [7][8], and the rotator cuff tendinopathy trial a single 5 mL injection under the acromion followed by 6 weeks of exercise [11]. In rotator cuff surgery, leukocyte-poor PRP was injected at the repair [12]. Hair trials injected PRP into the scalp over several sessions, and a network meta-analysis of 25 trials found larger 6-month density gains with more sessions at shorter intervals [16].

Risks

Reported risks2

ModerateVery common

Pain, swelling and other injection reactions

Shown in knee osteoarthritis trials to cause complications in 18.66% against 9.14% with comparison injections, more often than saline, almost all mild or moderate.

The numbers and sources
How common
Very common: more than 1 in 10 people.
Effect
Across 24 knee osteoarthritis trials, complications occurred in 18.66% given PRP and 9.14% given comparison injections, a number needed to harm of 11. Odds were higher than with saline (OR 4.88) and did not differ from hyaluronic acid (OR 1.33) or corticosteroids. One patient reported severe pain, and the rest were mild to moderate and self-limiting [17]. In the Achilles trial, injection site discomfort occurred in 97 of 121 given PRP and 73 of 119 given sham, swelling in 56 and 52, and bruising in 48 and 49 [7]. In tennis elbow trials, adverse events occurred in 19% with PRP or blood and 17% with placebo (RR 1.14, 95% CI 0.76 to 1.72) [6].
Population
2,751 patients in 24 knee trials [17]. 240 adults [7]. 425 participants in 5 elbow trials [6].
Sources
[17], [7], [6]
Caveats
The higher rate against saline was seen in knee trials. In tennis elbow trials the difference from placebo was not significant [6].
ModerateHow often is not known

Frozen shoulder after rotator cuff injections

Pooled trials found overall complications similar to other shoulder injections, and frozen shoulder more often after PRP.

The numbers and sources
How common
How often is not known: the sources give no rate.
Effect
Across 19 trials, complications occurred in 9.41% given PRP and 10.13% given comparison injections (P = .67), and frozen shoulder was significantly more frequent after PRP (P = .01). The most common complications were persistent pain, frozen shoulder, worsening of the tear and bursitis. No serious events were reported [18].
Population
1,043 patients with rotator cuff problems in 19 trials, 510 given PRP [18].
Sources
[18]
Caveats
The abstract does not give the frozen shoulder rate.

Claims tested and not found

  1. That PRP eases knee osteoarthritis pain at a year. Pain fell 2.1 points with PRP and 1.8 with saline at 12 months in 288 adults [2].
  2. That PRP eases tennis elbow. Pain and function did not differ from placebo by a clinically important amount at 3, 6 or 12 months [6].
  3. That PRP heals Achilles tendinopathy. VISA-A scores did not differ from sham at 6 months in 240 adults [7].
  4. That PRP eases rotator cuff tendinopathy beyond exercise. Scores did not differ from saline through one year in 40 patients [11].

Related

MinoxidilFinasteride

Sources

  1. Beitzel K, Allen D, Apostolakos J, et al. US definitions, current use, and FDA stance on use of platelet-rich plasma in sports medicine. The Journal of Knee Surgery. 2014. https://doi.org/10.1055/s-0034-1390030
  2. Bennell KL, Paterson KL, Metcalf BR, et al. Effect of Intra-articular Platelet-Rich Plasma vs Placebo Injection on Pain and Medial Tibial Cartilage Volume in Patients With Knee Osteoarthritis: The RESTORE Randomized Clinical Trial. JAMA. 2021. https://doi.org/10.1001/jama.2021.19415
  3. Auroux M, Debionne T, Mainbourg S, Chapurlat R. Efficacy of intra-articular platelet-rich plasma compared with placebo in knee osteoarthritis: A systematic review and meta-analysis. Joint Bone Spine. 2025. https://doi.org/10.1016/j.jbspin.2025.105947
  4. Delgado D, Andrade R, Gomes E, et al. Younger age and platelet-rich plasma characteristics influence short-term outcomes in knee osteoarthritis, but independent effects remain uncertain: A systematic review with meta-analysis and meta-regression of placebo-controlled randomised trials. Knee Surgery, Sports Traumatology, Arthroscopy. 2026. https://doi.org/10.1002/ksa.70567
  5. Belk JW, Lim JJ, Keeter C, et al. Patients With Knee Osteoarthritis Who Receive Platelet-Rich Plasma or Bone Marrow Aspirate Concentrate Injections Have Better Outcomes Than Patients Who Receive Hyaluronic Acid: Systematic Review and Meta-analysis. Arthroscopy. 2023. https://doi.org/10.1016/j.arthro.2023.03.001
  6. Karjalainen TV, Silagy M, O'Bryan E, et al. Autologous blood and platelet-rich plasma injection therapy for lateral elbow pain. Cochrane Database of Systematic Reviews. 2021. https://doi.org/10.1002/14651858.cd010951.pub2
  7. Kearney RS, Ji C, Warwick J, et al. Effect of Platelet-Rich Plasma Injection vs Sham Injection on Tendon Dysfunction in Patients With Chronic Midportion Achilles Tendinopathy: A Randomized Clinical Trial. JAMA. 2021. https://doi.org/10.1001/jama.2021.6986
  8. de Vos RJ, Weir A, van Schie HT, et al. Platelet-rich plasma injection for chronic Achilles tendinopathy: a randomized controlled trial. JAMA. 2010. https://doi.org/10.1001/jama.2009.1986
  9. de Jonge S, de Vos RJ, Weir A, et al. One-year follow-up of platelet-rich plasma treatment in chronic Achilles tendinopathy: a double-blind randomized placebo-controlled trial. The American Journal of Sports Medicine. 2011. https://doi.org/10.1177/0363546511404877
  10. Roy M, Reddy MH, Das D, et al. Effectiveness of Platelet-Rich Plasma in Treating Rotator Cuff Tendinopathy: A Systematic Review and Meta-Analysis. Journal of Orthopaedic Case Reports. 2025. https://doi.org/10.13107/jocr.2025.v15.i03.5408
  11. Kesikburun S, Tan AK, Yilmaz B, et al. Platelet-rich plasma injections in the treatment of chronic rotator cuff tendinopathy: a randomized controlled trial with 1-year follow-up. The American Journal of Sports Medicine. 2013. https://doi.org/10.1177/0363546513496542
  12. Pitsilos C, Rigkos D, Chalidis B. Injection of Leukocyte-Poor Platelet-Rich Plasma During Rotator Cuff Repair Can Increase Healing Rate but Does Not Affect Clinical Outcomes: A Systematic Review and Meta-analysis of Randomized Controlled Trials. Arthroscopy. 2026. https://doi.org/10.1002/arj.70537
  13. Zhang X, Ji Y, Zhou M, et al. Platelet-Rich Plasma for Androgenetic Alopecia: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Journal of Cutaneous Medicine and Surgery. 2023. https://doi.org/10.1177/12034754231191461
  14. Yuan J, He Y, Wan H, Gao Y. Effectiveness of platelet-rich plasma in treating female hair loss: A systematic review and meta-analysis of randomized controlled trials. Skin Research and Technology. 2024. https://doi.org/10.1111/srt.70004
  15. Umar M, Anwar A, Shamim L, et al. Comparative Efficacy and Safety of Platelet Rich Plasma (PRP) versus Topical Minoxidil for Androgenetic Alopecia: A Systematic Review and Meta-analysis. Aesthetic Plastic Surgery. 2026. https://doi.org/10.1007/s00266-025-05394-7
  16. Gupta AK, Bamimore M. Platelet-Rich Plasma Monotherapies for Androgenetic Alopecia: A Network Meta-Analysis and Meta-Regression Study. Journal of Drugs in Dermatology. 2022. https://doi.org/10.36849/jdd.6948
  17. Fucaloro SP, Bragg J, Berhane M, et al. Complications of Platelet-Rich Plasma Injection for Knee Osteoarthritis Are Similar to Those of Corticosteroids and Hyaluronic Acid but Are Significantly Greater Than Those of Placebo Injections: A Meta-analysis of Randomized Controlled Trials. Arthroscopy. 2025. https://doi.org/10.1016/j.arthro.2025.05.018
  18. Driscoll A, Griffin S, Schreiner G, et al. Platelet-Rich Plasma Injections for the Treatment of Rotator Cuff Pathology Have Higher Complication Rates of Adhesive Capsulitis than Alternative Injectable Therapies: A Systematic Review and Meta-analysis of Randomized Controlled Trials. Arthroscopy. 2026. https://doi.org/10.1002/arj.70163

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