How Long Does PRP Last? Duration, Factors, and When to Repeat

PRP (platelet-rich plasma) injections usually help for about 6 to 18 months, and the length depends on what is being treated: roughly 12 to 18 months for mild to moderate knee osteoarthritis, 6 to 12 months for hair restoration, and 6 to 9 months for facial rejuvenation. Tendon injuries such as tennis elbow can stay improved for 2 years or longer after one injection, according to a randomized trial by Gosens and colleagues (2011), while the larger RESTORE trial (Bennell and colleagues, JAMA, 2021) found knee PRP no better than saline at 12 months, so individual results vary widely.

“How long will this last?” is the first question most patients ask after learning about PRP therapy. It is a fair question, especially when you are paying out-of-pocket for a treatment that insurance rarely covers.

The honest answer is that it depends. PRP duration varies significantly based on what condition you are treating, how advanced the damage is, the quality of the PRP preparation, and several individual factors. The sections below set out what the clinical evidence shows for each major application, including where the trials disagree, so you can set realistic expectations before committing to treatment.

Why PRP Results Are Not Permanent

PRP works by delivering a concentrated dose of growth factors that trigger a repair response in damaged tissue. Unlike a surgical repair that physically restructures anatomy, or a drug that stays in your system at a steady dose, PRP creates a temporary biological window of accelerated healing [1].

Once injected, platelets activate within minutes and begin releasing growth factors. This release continues for about 7 to 10 days. The tissue remodeling those growth factors initiate lasts weeks to months. But PRP does not stop the underlying disease process. In osteoarthritis, for example, the mechanical wear and inflammatory cycle that breaks down cartilage continues even after PRP has done its work. Eventually, the benefits fade as the disease progresses, and retreatment becomes necessary.

Think of PRP as hitting the reset button on a degenerative process rather than stopping it. How long that reset lasts depends on how fast the degenerative process is moving.

The growth factors released by activated platelets include platelet-derived growth factor (PDGF), transforming growth factor beta (TGF-β) and vascular endothelial growth factor (VEGF), as Marx (2004) and Everts and colleagues (2006) describe in their reviews [1][11]. These signals recruit repair cells and new blood vessels for a limited time. Duration therefore depends less on the injection itself and more on whether the tissue it sets in motion can hold its gains.

How Long Does PRP Take to Work?

PRP usually takes 2 weeks to 3 months to show a noticeable effect, because the benefit comes from tissue repair rather than from a drug acting immediately. Mild soreness at the injection site is common for a few days, and many clinicians ask patients to avoid anti-inflammatory painkillers during that window. A detailed day-by-day picture of the first weeks is in our article on PRP recovery time.

The timeline below combines the onset and peak figures stated for each condition later on this page. It is a typical pattern, not a schedule your body will follow exactly.

PRP Duration for Knee Osteoarthritis: 12 to 18 Months

Knee OA is the most studied PRP application, so the data here are the deepest, and also the most contested. Several randomized controlled trials have followed patients for 12 months, and their results point in different directions. People searching for osteoarthritis treatment options should weigh both sides.

What the Research Shows

A meta-analysis of 10 randomized controlled trials with 1,069 patients, published by Dai and colleagues in Arthroscopy in 2017, found that PRP and hyaluronic acid performed similarly at 6 months, but PRP provided statistically significant improvements in pain and function at 12 months compared to hyaluronic acid and saline placebo [2]. Individual trials show how the benefit rises and fades:

• Filardo and colleagues (2012) compared three weekly PRP injections with hyaluronic acid in 109 patients over 12 months; both groups improved, PRP was not better overall, and the more promising PRP results came in patients with low-grade cartilage degeneration [3].
• Patel and colleagues (2013) found that one or two PRP injections reduced pain and stiffness compared with saline within 2 to 3 weeks, with benefit lasting to the 6-month follow-up and starting to slip at that point [4].
• Kon and colleagues (2018), in a 46-patient pilot trial of autologous protein solution (a concentrate made from the patient’s own blood, closely related to PRP), reported that WOMAC pain had improved by 65% in the treated group versus 41% with saline at 12 months [5].
• The RESTORE trial by Bennell and colleagues (JAMA, 2021) gave 288 people with mild to moderate knee OA three weekly injections of PRP or saline and found no significant difference in pain or medial tibial cartilage volume at 12 months [12].

The honest reading is that PRP helps some knees for about a year, the average advantage over placebo is debated, and nobody can yet predict reliably who will respond. Our overview of PRP for knee pain and osteoarthritis covers technique and candidacy in more depth.

Duration by OA Severity

Kellgren-Lawrence Grade	Typical Duration of Benefit	Notes
Grade I (Mild)	15 to 24 months	Best responders; some patients go 2+ years between treatments
Grade II (Moderate)	12 to 18 months	Solid response; annual retreatment common
Grade III (Moderate-Severe)	6 to 12 months	Shorter duration; may need retreatment every 6 to 9 months
Grade IV (Severe)	3 to 6 months (if any)	Limited benefit; structural damage too advanced for biologics alone

The pattern is consistent: less damage means longer-lasting results. These ranges reflect clinical experience and the subgroup findings above rather than a single trial that measured each grade. This is why early intervention with PRP, before the joint reaches end-stage disease, makes the most strategic sense.

Retreatment Protocol for Knees

Most orthopedic and sports medicine specialists recommend reassessing at 12 months. If symptoms have returned significantly, a single booster injection often restores benefits without repeating the full initial series. Some patients settle into an annual maintenance injection that keeps them functional; whether this delays knee replacement has not been tested in long-term trials, so treat that as a hope rather than an expected result [5].

PRP Duration for Hair Restoration: 6 to 12 Months

PRP for hair loss works by injecting concentrated platelets into the scalp to stimulate dormant hair follicles, increase blood supply to follicular units, and prolong the growth (anagen) phase of the hair cycle [6]. It is used mainly for androgenetic alopecia (male and female pattern hair loss), usually by dermatologists and hair restoration physicians. For more on how scalp PRP compares with other options, see our guide to hair loss treatment and the dedicated article on PRP for hair loss.

What the Research Shows

A randomized, placebo-controlled half-head trial by Gentile and colleagues, published in Stem Cells Translational Medicine in 2015, found that PRP-treated areas showed significant increases in hair count and hair density after three treatment cycles compared to placebo [6]. The same team followed patients for 2 years, and 4 of the 20 who completed the study reported progressive hair loss again 12 months after their last session, which became more evident at 16 months. Other studies and clinical experience track a similar arc:

• Peak results typically appear at 3 to 6 months after the initial treatment series (usually 3 sessions spaced 4 weeks apart).
• Benefits begin to plateau around 6 to 9 months.
• Without maintenance treatments, most patients notice a gradual return toward baseline by 12 to 18 months [7].

Why Hair PRP Needs Regular Maintenance

Hair follicles cycle continuously between growth, regression, and rest phases. PRP extends the growth phase and reactivates resting follicles, but it does not permanently alter the hormonal and genetic factors that drive pattern hair loss. Once the growth factor stimulus fades, follicles gradually revert to their pre-treatment behavior.

Recommended Maintenance Schedule

Most dermatologists and hair restoration specialists recommend:

• Initial series: 3 treatments spaced 4 to 6 weeks apart
• First maintenance: 3 to 4 months after the last initial treatment
• Ongoing maintenance: Every 4 to 6 months indefinitely

Patients who combine PRP with finasteride or minoxidil often see longer-lasting results between maintenance sessions, because the medications address the hormonal component while PRP addresses the growth factor component [7]. These schedules are clinical conventions rather than trial-tested intervals, and PRP for hair loss is an off-label, cash-pay procedure in the United States.

PRP Duration for Facial Rejuvenation: 6 to 9 Months

PRP facial treatments (sometimes called the “vampire facial” when combined with microneedling) work by stimulating collagen production and skin cell turnover in the treated areas [8]. They are offered by dermatologists, plastic surgeons and medical aesthetics practices, often alongside microneedling or laser resurfacing. Our article on PRP for the face covers techniques and candidacy.

What to Expect

• Initial improvements in skin texture and hydration appear within 2 to 4 weeks as the initial collagen remodeling begins.
• Peak results typically occur at 2 to 3 months, when new collagen deposition is at its highest.
• Benefits persist for approximately 6 to 9 months before gradual decline.
• Some patients report improvements lasting up to 12 months, particularly when PRP is combined with microneedling, though this comes mostly from clinical reports rather than controlled trials.

The best controlled data are modest. In a split-face randomized trial by Alam and colleagues (JAMA Dermatology, 2018), participants rated the PRP-treated side as more improved than the saline side for texture and wrinkles 6 months after a single injection, while blinded raters found PRP only nominally, not significantly, better [8].

Factors Affecting Facial PRP Duration

Age, sun exposure history, skin type, and smoking status all influence how long results last. Younger patients with better baseline skin quality tend to hold results longer. Patients who maintain a consistent skincare routine with sunscreen, retinoids, and antioxidants also extend the duration of their results.

Maintenance for Facial PRP

Most providers recommend treatments every 6 to 9 months for ongoing maintenance, or 2 to 3 sessions per year. Some patients schedule treatments seasonally, using the downtime during lower-sun months to optimize recovery.

PRP Duration for Tendon Injuries: Variable, Often Long-Lasting

Tendons respond differently to PRP than degenerative joints or cycling hair follicles. When PRP successfully stimulates tendon repair, the results can be structural and lasting rather than temporary. Tendinopathy is usually treated by sports medicine physicians, orthopedic surgeons and physiatrists, often with ultrasound guidance.

Lateral Epicondylitis (Tennis Elbow)

A well-known RCT by Gosens and colleagues (American Journal of Sports Medicine, 2011) compared PRP to cortisone for chronic lateral epicondylitis and found that PRP produced superior outcomes at 1 year, with benefits persisting through the 2-year follow-up while the cortisone group's disability scores returned to baseline [9]. Unlike cortisone (which provided better short-term relief but worse long-term outcomes), PRP appeared to promote actual tissue healing rather than just symptom suppression. More on the condition itself is on our tennis elbow page.

Many patients with tennis elbow who respond to PRP do not need repeat treatment. The tendon heals, and the problem resolves.

Achilles Tendinopathy

Results for Achilles tendon issues are more mixed. Some studies show meaningful improvement, while others show no significant benefit over placebo. The best known, a double-blind JAMA trial of 54 patients by de Vos and colleagues (2010), found that PRP plus an eccentric exercise program did no better than saline plus the same exercises at 24 weeks [13]. When PRP does seem to help Achilles tendinopathy, results tend to develop slowly (over 3 to 6 months) and can be long-lasting.

Patellar Tendinopathy (Jumper’s Knee)

A randomized trial by Vetrano and colleagues (2013) comparing PRP to extracorporeal shockwave therapy for jumper's knee in athletes found that both treatments helped, with PRP showing better results at 6 and 12 months [14]. A smaller double-blind trial by Dragoo and colleagues (2014) found PRP sped early improvement at 12 weeks compared with dry needling, but the advantage was gone by 26 weeks [10]. Repeat treatment is sometimes necessary, but many patients achieve lasting relief after one or two injections combined with a structured rehabilitation program.

PRP Duration Summary by Condition

Across the conditions covered above, PRP benefit typically lasts 6 to 24 months, longest in mild knee osteoarthritis and healed tendons and shortest in hair and skin, where maintenance is the norm. The table pulls the figures together.

Condition	Time to Peak Results	Duration of Benefit	Maintenance Frequency
Knee OA (mild)	6 to 12 weeks	15 to 24 months	Every 12 to 24 months
Knee OA (moderate)	6 to 12 weeks	12 to 18 months	Every 12 months
Hair restoration	3 to 6 months	6 to 12 months	Every 4 to 6 months
Facial rejuvenation	2 to 3 months	6 to 9 months	Every 6 to 9 months
Tennis elbow	6 to 12 weeks	Often lasting (1 to 2+ years)	Often not needed
Achilles tendinopathy	3 to 6 months	Variable	As needed
Patellar tendinopathy	2 to 4 months	12+ months	As needed

Does PRP Last Longer Than Cortisone or Hyaluronic Acid?

PRP tends to last longer than a cortisone (corticosteroid) injection but takes longer to start working. Cortisone usually brings relief within days, and that relief commonly fades over weeks to a few months. In the Gosens tennis elbow trial, cortisone patients returned to baseline by 2 years while PRP patients stayed improved [9]. Our comparison of PRP vs cortisone injections goes through the trade-offs in detail.

Against hyaluronic acid (viscosupplementation) for knee osteoarthritis, the picture is closer. The Dai meta-analysis found the two similar at 6 months, with PRP ahead at 12 months [2], while Filardo and colleagues found no overall difference at 12 months [3]. Other regenerative injections, such as prolotherapy and stem cell or exosome products, have thinner duration data than PRP; see prolotherapy vs PRP and our stem cell therapy guide for those comparisons.

Factors That Affect How Long PRP Lasts

Several variables influence the duration of PRP results, regardless of the condition being treated.

1. PRP Preparation Quality

Not all PRP is created equal. The platelet concentration, the volume injected, and whether the preparation is leukocyte-rich or leukocyte-poor all affect outcomes. Marx (2004) proposed that therapeutic PRP should contain roughly four to five times the normal platelet count of blood, and systems that achieve higher platelet concentrations (5x to 8x baseline) are thought to produce longer-lasting results than those yielding lower concentrations [1][3]. Because preparation methods vary so much between clinics and devices, trials are hard to compare, which is one reason the knee evidence conflicts.

2. Severity of the Condition

This is the single biggest predictor of duration. Early-stage disease responds better and longer than advanced disease. A patient with mild knee OA will usually get more mileage from a PRP injection than someone with bone-on-bone arthritis, a pattern Filardo and colleagues also saw in their low-grade subgroup [3].

3. Age

Younger patients generally produce higher-quality platelets with more growth factors. Some laboratory work suggests that PRP from patients under 50 tends to have higher concentrations of key growth factors than PRP from older patients, although the effect on clinical duration has not been measured well [11].

4. Body Weight

For knee OA specifically, body weight directly affects how long results last. Excess weight increases mechanical load on the joint, accelerating cartilage wear and shortening the benefit window. Weight management is one of the most impactful things you can do to extend PRP results.

5. Activity Level and Rehabilitation

PRP works best when paired with appropriate physical therapy and gradual return to activity. Patients who follow a structured rehabilitation program after PRP injection tend to have better and longer-lasting outcomes than those who skip therapy [5].

6. Smoking

Smoking impairs tissue healing at every level, from reduced blood flow to impaired growth factor signaling. Smokers are widely expected to have shorter-duration PRP results, although few PRP trials report outcomes by smoking status [11].

7. Medications

Chronic use of NSAIDs (ibuprofen, naproxen) can blunt PRP’s effectiveness. These drugs work by suppressing the inflammatory cascade, which is exactly the mechanism PRP relies on. If you are taking NSAIDs regularly, discuss alternatives with your provider before starting PRP therapy.

When to Repeat PRP Treatments

Rather than scheduling repeat treatments on a fixed calendar, the most effective approach is symptom-guided retreatment. Pay attention to when you notice a return of symptoms. For knee OA patients, this might mean:

• Increased stiffness after sitting for long periods
• Return of pain during stairs or squatting
• Reduced walking tolerance
• Needing to take acetaminophen more often

When these symptoms start creeping back, it is time to discuss a booster injection with your provider. Most patients develop a predictable pattern after their first treatment cycle, making future scheduling easier to plan. For hair and skin, repeats are usually planned in advance, every 4 to 6 months for the scalp and every 6 to 9 months for the face, as described in the sections above.

How Many PRP Injections Do You Need?

The number of PRP injections depends on the condition, and protocols are not standardized. In the trials cited here, knee osteoarthritis was treated with one to three injections: Patel and colleagues used one or two [4], while Filardo and colleagues and the RESTORE trial used three weekly injections [3][12]. Hair restoration usually starts with 3 sessions about a month apart, facial PRP is often given as a short series, and tendon studies such as Gosens and colleagues used a single injection [9].

More injections have not been shown to make results last proportionally longer. Ask any clinic what protocol it uses, why, and how it will judge whether a repeat is worthwhile.

Is Repeat PRP Covered by Insurance?

Repeat PRP is usually paid out of pocket, because most US insurers, including Medicare in most cases, treat PRP injections for joints, tendons, hair and skin as unproven. The FDA clears the centrifuge systems used to prepare PRP as medical devices, and using that PRP for knee, tendon, scalp or facial injections is a clinician’s off-label choice rather than an FDA-approved indication. Because benefit fades, the lifetime cost of maintenance matters as much as the first visit. Our PRP injection cost article explains what drives pricing.

When to See a Doctor

Talk to a specialist about PRP treatment timing if:

• You had PRP previously and are noticing symptom recurrence
• You want to understand whether your condition is a good candidate for long-lasting PRP results
• You have been getting cortisone injections and want to explore a treatment that may last longer and preserve tissue health
• You are unsure whether PRP or surgery makes more sense for your situation

For a full overview of PRP therapy, how it works, costs, and applications, read our PRP therapy guide. If knee OA is your primary concern, see our detailed article on PRP injection for knee pain.

The clinicians who give PRP most often are orthopedic surgeons, sports medicine physicians, physiatrists (physical medicine and rehabilitation doctors), pain medicine specialists and dermatologists. You can compare practices in the PRP clinic directory, and our platelet-rich plasma treatment guide explains the procedure and its evidence. On Regenerated.com, listing order is not paid ranking, Featured slots are labeled and capped, Verified means credential checks rather than spend, and the directory is free for patients. Inclusion in the list is not an endorsement, so ask each clinic how it prepares PRP and how it measures results.

The Bottom Line

PRP is not a one-and-done fix for most conditions. For knee osteoarthritis, expect 12 to 18 months of benefit before a booster is needed, if your knee responds at all. For hair restoration, plan on maintenance every 4 to 6 months. For facial rejuvenation, 6 to 9 months is typical. For tendon injuries, you may get lucky with lasting structural repair, or you may need a second round.

The most productive way to think about PRP is as a maintenance strategy rather than a permanent fix. Some clinicians believe it slows disease progression while it manages symptoms, which would set it apart from options like cortisone that provide temporary relief at the potential cost of accelerated tissue breakdown, though the RESTORE trial found no cartilage benefit at 12 months [12]. Knowing what to expect for duration allows you to plan your treatments, budget your costs, and make informed decisions about your long-term care.

Frequently asked questions

How long does a PRP injection last in the knee?

A PRP injection in the knee usually helps for about 12 to 18 months in mild to moderate osteoarthritis, and up to 2 years in some people with very mild disease. Advanced, bone-on-bone arthritis often gets 6 months or less. Some knees do not respond at all: a 2017 meta-analysis favored PRP at 12 months, while the 2021 RESTORE trial in JAMA found it no better than saline.

How long does PRP last for hair loss?

PRP for hair loss usually keeps its effect for about 6 to 12 months after the initial series of three sessions. Results tend to peak 3 to 6 months after the series and then slowly fade, because PRP does not change the hormonal and genetic drivers of pattern hair loss. Most dermatologists suggest maintenance sessions every 4 to 6 months, often alongside minoxidil or finasteride.

Is PRP permanent?

PRP is not permanent for degenerative or cyclical problems such as knee osteoarthritis, pattern hair loss or aging skin, because the underlying process continues after the growth factors fade. Tendon injuries are the main exception. In the Gosens tennis elbow trial, patients treated with a single PRP injection were still improved at 2 years, and many people with a healed tendon never need a second injection.

How soon can you repeat PRP injections?

PRP injections can be repeated as soon as a few weeks apart during an initial series, and maintenance repeats are usually spaced by months. Knee protocols in trials used one to three injections given weekly or a few weeks apart. Hair series are usually spaced 4 to 6 weeks apart. After the first cycle, most clinicians repeat PRP only when symptoms return rather than on a fixed calendar.

Does PRP last longer than a cortisone shot?

PRP usually lasts longer than a cortisone shot, but it works more slowly. Cortisone can ease pain within days and often wears off within weeks to a few months. In a randomized tennis elbow trial by Gosens and colleagues (2011), cortisone patients returned to baseline by 2 years while PRP patients remained improved. For knee osteoarthritis, head-to-head duration data between PRP and cortisone are more limited.

Why did my PRP stop working?

PRP usually stops working because the condition underneath it keeps progressing after the growth factor effect fades. Other common reasons are advanced disease at the start, a low platelet concentration, regular use of anti-inflammatory painkillers, excess body weight on an arthritic knee, smoking and skipping rehabilitation. Some people simply do not respond. A specialist can reassess whether a booster, a different preparation or another treatment makes more sense.

Related Reading

• PRP Therapy: The Complete Guide
• PRP Injection for Knee Pain
• Stem Cell Therapy Guide
• Exosome Therapy vs PRP
• PRP vs Stem Cell Therapy

Sources

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