Because PRP is prepared from your own blood, it is generally considered safe; the most common side effects are pain, tenderness, mild swelling and bruising at the injection site that last a few days. Serious complications such as infection are rare, and the risk depends largely on careful patient selection and a sterile technique.
Platelet-Rich Plasma (PRP) therapy involves injecting plasma enriched with platelets from the patient’s own blood to support healing in various orthopedic problems and sports injuries. It is now widely used for cartilage damage, tendon problems and joint disorders, and with that come common questions such as “Is PRP harmful?” and “What are the side effects of PRP in the knee?” This article explains the possible side effects, how long they usually last, which situations increase the risk and when you should contact a doctor.
How is PRP performed?
PRP concentrates the natural healing factors found in platelets with the aim of supporting tissue repair. A blood sample taken from the arm is processed in a special centrifuge to separate and concentrate the platelets. The resulting plasma is then usually injected directly into the injured tissue or into the joint, sometimes under ultrasound guidance. The goal is to support local healing and reduce pain. For more on the method and how it compares with stem cells, see our page on cellular therapies (PRP and stem cells).
What is PRP used for?
In orthopedics and traumatology, PRP may be considered for meniscus tears, anterior cruciate ligament injuries, cartilage damage, tendinitis, hip and knee osteoarthritis and gluteus medius tears. It may also be used in sports injuries such as athletic pubalgia, femoroacetabular impingement and labral tears, and to support healing after some operations. The response differs from case to case, and results vary between individuals.
What are the side effects of PRP?
Scientific literature generally describes PRP as a safe treatment. However, like any medical procedure, it can have side effects. The most common include:
- Pain and swelling at the injection site: mild pain, tenderness and sometimes slight swelling, which usually settle on their own within a few days.
- Bleeding or bruising: small bleeds and bruises lasting a few days, especially where small blood vessels are dense.
- Temporary stiffness: brief stiffness or limited movement while the tissue responds to the injection.
- Infection: because blood is drawn and re-injected, strict sterile conditions are essential; without them, infection may develop, although it is rare.
- Allergic reaction: extremely rare, since the plasma comes from your own blood. Reactions to a local anesthetic or other medicines, or bleeding problems related to blood thinners, are still possible.
Less common events include a marked inflammatory reaction, a temporary increase in pain and, particularly in advanced or long-standing conditions, a lack of response to treatment. Not responding is not harm in itself, but realistic expectations should be discussed beforehand.
Side effects of knee PRP
The knee is one of the joints most often treated with PRP. After an injection into the knee joint you may notice:
- Fullness, tightness and pain for the first 24–72 hours
- Mild swelling and temporary difficulty bending the knee fully
- A small bruise at the injection point
In most patients these ease within a few days. For pain, a painkiller such as paracetamol recommended by your doctor is usually preferred over anti-inflammatory drugs, which may reduce the effect of PRP. For day-by-day advice, read our guide to post-PRP care.
Is PRP harmful? Situations that increase the risk
When performed in a suitable patient under sterile conditions, PRP usually causes only limited, temporary side effects. Risk is mostly linked to unsuitable patient selection or conditions. PRP may not be appropriate, or may need extra caution, in the following situations:
- Active infection at the injection site or elsewhere in the body
- Blood disorders that affect platelet number or function
- Use of blood thinners (never stop these without talking to your doctor)
- Active cancer treatment or certain serious systemic illnesses
- Pregnancy
We discuss these in more detail in who is not suitable for PRP treatment. Telling your doctor about all medicines and past illnesses is one of the most important ways to reduce risk.
A note on hair PRP
Questions about the harms of hair PRP are also common. Hair and skin treatments belong to dermatology; the information here applies to joint, tendon and muscle injections. Please direct questions about hair PRP to a specialist in that field.
Precautions after PRP
Patients are advised to avoid intense physical activity for several days after treatment and to keep the injection site clean to prevent infection. Follow your doctor’s instructions on painkillers and any other medicines. Treatment sometimes involves more than one session and should be carried out under specialist supervision.
An orthopedic view on PRP safety
Orthopedic specialists emphasize that PRP is a safe method when used for the right indications and under sterile conditions. Because its side effects are usually mild and temporary, it may be considered as a complementary option in suitable cases, particularly for athletes and active people. As with any treatment, patient selection, technique and follow-up are decisive. At Prof. Dr. Gökhan Polat’s clinic, the decision on PRP is made individually after examination and the necessary tests.
When should you see an orthopedic specialist?
Mild pain and swelling after PRP are expected. Contact your doctor promptly if you notice:
- Pain and swelling that increase over the days instead of settling
- Marked redness, warmth or discharge at the injection site
- Fever, chills or feeling generally unwell
- Inability to move the joint or bear weight
In summary
PRP is generally safe because it is prepared from your own blood. The most common side effects are pain, swelling and bruising lasting a few days; serious problems such as infection are rare. Careful patient selection, a sterile technique and following aftercare advice help reduce the risks, and results vary from person to person.
This article is for general information only; diagnosis and treatment decisions are made individually after examination and the necessary tests.
Frequently asked questions
Is PRP therapy a painful procedure
Mild discomfort may be felt during the PRP injection, but it is generally well tolerated by most patients. Mild pain after the procedure is normal and typically subsides quickly.
How long do the side effects of PRP therapy last?
Most side effects, such as pain, swelling, and tenderness at the injection site, resolve spontaneously within a few days.
Can PRP therapy be applied at any age?
PRP therapy is generally preferred for adult patients. Age and overall health condition determine suitability, so expert evaluation is necessary.
What is the risk of infection after PRP therapy?
Infection risk is very low when the procedure is performed under sterile conditions; however, no treatment is entirely risk-free.
Can I exercise immediately after PRP therapy?
Rest for a few days is recommended after treatment. Early physical activity may increase the risk of complications and reduce the treatment's effectiveness.
Is PRP harmful?
Because PRP is prepared from your own blood, it is generally considered safe when performed in a suitable patient under sterile conditions. The most common side effects are pain, swelling and bruising lasting a few days. It may not be appropriate in situations such as active infection, certain blood disorders or blood thinner use, so the decision should be made after examination.
Is knee pain normal after PRP?
Fullness, tightness and pain in the first 24–72 hours after knee PRP are common and usually ease within a few days. During this time, a painkiller recommended by your doctor is preferred over anti-inflammatory drugs. If pain keeps increasing, the knee becomes red and warm, or you develop a fever, you should contact your doctor.
