What Is PRP (Platelet-Rich Plasma)? Uses and Evidence

PRP — platelet-rich plasma — is one of the most talked-about treatments in sports medicine, orthopaedics, and aesthetics, used by elite athletes and advertised on every clinic's menu. But behind the hype, what actually is it, and does it work? This is an honest, plain-language guide: what PRP is, how it is made, what the evidence genuinely shows, and how it differs from stem-cell therapy. For the wider field it sits within, see our overview of regenerative medicine.

What is PRP?

PRP is made from your own blood. A small sample is drawn and spun in a centrifuge to concentrate the platelets — the tiny cell fragments best known for clotting — into a small volume of plasma, typically at two to three times their normal concentration. That concentrate is then injected back into an injured or painful area. Because platelets are packed with growth factors — signalling molecules the body uses during healing — the idea is to deliver a concentrated dose of those repair signals right where they are wanted.

The key thing to hold onto is that PRP is autologous: it comes from you, and goes back into you, on the same day.

How is PRP made?

The process is quick and done in the clinic in one visit:

There is no donor and no laboratory culturing of cells, which is part of why PRP carries a relatively low regulatory and safety burden compared with cell-based therapies.

How is it thought to work?

When platelets are concentrated and delivered to a site of injury, they release a cocktail of growth factors — including PDGF, TGF-β, and VEGF — that the body normally uses to drive the phases of healing: calming inflammation, encouraging new tissue, and remodelling it ¹. The theory is that boosting these signals can nudge a stalled or slow-healing area toward repair. It is a reasonable, biology-based idea — but, as always, "biologically plausible" is not the same as "reliably effective," which is where the evidence comes in.

What is it used for — and what does the evidence say?

PRP has been studied across a wide range of musculoskeletal problems, and this is where honesty matters most, because the marketing often runs ahead of the data:

• Knee osteoarthritis. This is the most-studied use. A 2025 review found that certain PRP formulations (leukocyte-poor PRP) can offer better pain and function than hyaluronic acid or corticosteroid injections in mild-to-moderate knee OA — but it stressed that results are inconsistent and that the huge variation in how PRP is prepared limits how comparable the studies even are ².
• Tendon problems — tennis elbow, plantar fasciitis, and other tendinopathies are common targets, with mixed but sometimes encouraging results.
• Sports and muscle injuries, and some other orthopaedic conditions, where evidence-based indications exist but vary in strength ³.
• Aesthetic and hair uses (the "vampire facial," hair-loss injections) are heavily marketed, but the evidence here is generally weaker and more variable than for joints and tendons.

The honest summary: PRP is promising for certain musculoskeletal conditions, not proven for everything, and outcomes depend a great deal on the specific preparation, the condition, and the person. It is best thought of as a possible adjunct for selected problems — usually after conservative care — rather than a cure-all.

PRP vs stem-cell therapy — they are not the same

These two get lumped together, but they are different things:

• PRP concentrates platelets and their growth factors from your blood. There are no stem cells in it. It is simpler, quicker, and faces a lower regulatory bar.
• Stem-cell therapy uses living cells (often from bone marrow or fat) with the aim of contributing to repair directly. It is more complex, more tightly regulated, and — as we explain in our overview of regenerative medicine — also largely unproven for most uses.

Conflating the two is a common marketing tactic; they deserve to be judged on their own, separate evidence.

What does a session involve, and how many?

A session is straightforward: a blood draw, a short spin to prepare the PRP, and an injection — often guided by ultrasound for accuracy — usually over less than an hour. Many protocols use a course of injections rather than a single one, and there is typically some soreness at the site for a few days afterwards as the intended inflammatory-repair response gets going. Improvement, if it comes, tends to be gradual over weeks, not immediate.

Is PRP safe?

Because PRP is made from your own blood, the risk of an allergic reaction or transmitted infection is very low — one of its genuine advantages. The most common effects are temporary pain, swelling, or bruising at the injection site. The bigger risk with PRP is rarely physical; it is paying for an expensive course of injections for a condition or a use where the evidence does not really support it.

What to ask before you have PRP

Because PRP quality and evidence vary so much, a few questions help separate a considered offer from a sales pitch:

• "What does the evidence say for my condition?" PRP has more support for some problems (like knee osteoarthritis) than others — a good clinic will tell you where yours sits.
• "How is the PRP prepared?" Preparation drives results, and the honest answer is that there is no single agreed standard — but the clinic should at least be able to explain what they do.
• "Is this instead of, or alongside, conservative care?" PRP is usually best as an adjunct after the basics, not a replacement for them.
• "What are the realistic odds and the cost of a full course?" Be wary of anyone promising a cure, or quoting one injection when a course is intended.

What we see at the clinic

People often ask for PRP by name, having seen an athlete or an advert endorse it. Our job is to be straight about where it genuinely has support — certain joint and tendon problems, usually as an adjunct after the basics — and where it is being oversold. Where it might be a reasonable option, it is physician-led and offered only after assessment, with honest expectations rather than a promise.

Common questions

Is PRP the same as stem-cell therapy? No. PRP concentrates platelets and growth factors from your blood and contains no stem cells; stem-cell therapy uses living cells. They are different treatments with different evidence.

Does PRP hurt? The injection and a few days of soreness afterwards are common, since PRP works partly by kick-starting an inflammatory-repair response. Most people tolerate it well.

How soon will I see results? If PRP helps, the change is usually gradual over several weeks, not immediate — and a course of injections is often used rather than a single shot.

Is PRP proven to work? For some conditions, such as mild-to-moderate knee osteoarthritis and certain tendon problems, there is supportive evidence — but it is inconsistent and depends heavily on preparation, so it is not a guaranteed fix.

Does PRP regrow hair or rejuvenate skin? It is marketed heavily for both, but the evidence for aesthetic and hair uses is generally weaker and more variable than for joints and tendons — so approach those claims with extra caution. Our guide to regenerative skin treatments covers the aesthetic side — and the safety — in depth.

Key takeaway

PRP is a genuine, low-risk, autologous treatment that concentrates your blood's own growth factors — and it has real, if inconsistent, support for certain joint and tendon conditions, usually as an adjunct after conservative care. It is not stem-cell therapy, and it is not the cure-all the marketing implies. Treat it as one tool among several, judge it on its own evidence, and decide with a clinician rather than a brochure.