Knee injections have become a common treatment for managing arthritis pain, offering many people much-needed relief and improved mobility. While these treatments are often promoted as quick and effective solutions, it’s important to also understand the potential risks and downsides. Choosing the right arthritis treatment can be confusing, which is why clear, balanced information is essential to help you make the best decisions for your health.

The Common Side Effects and Complications of Knee Injections

Knee injections aim to reduce pain, lower inflammation, and improve joint function for those with arthritis. However, no medical procedure is completely free from risk.

Short-term side effects are quite common but usually mild. After an injection, you may experience some pain, swelling, or bruising around the knee—these usually settle within a few days with little or no treatment.

Occasionally, more serious problems can arise. These might include allergic reactions to the injection, infection at the injection site, or damage inside the joint. While these complications are rare, they do require prompt medical attention. Importantly, a large meta-analysis pointed out that “most complications were reported as mild to moderate, and the odds of complications are similar to that of hyaluronic acid or corticosteroid injections” (Fucaloro et al., 2025). Knowing about these risks helps set realistic expectations.

Rare but Serious Risks: What Patients Should Know

Most side effects from knee injections tend to be minor and short-lived, but rare serious risks do exist. These can include infections that affect the joint, slower healing, unintended damage to cartilage or surrounding tissues, and systemic allergic reactions.

Certain factors can increase the risk of these complications, such as having a weakened immune system, previous joint problems, or known allergies. Although these risks are uncommon, it’s crucial to be aware of them to make informed decisions.

Research also warns that “the use of platelet-rich plasma (PRP) for knee osteoarthritis is not without risk, with a significantly higher rate of complications compared to placebo.” Still, the majority of these complications are mild (Fucaloro et al., 2025).

On the other hand, a recent study reassuringly found “no infection complications in either dialysis or non-dialysis patients” after steroid injections for knee arthritis (Tabata et al., 2023). This shows that while serious risks are possible, they aren’t guaranteed and depend on careful patient selection and clinical practice.

Looking beyond traditional injections, newer treatments such as stromal vascular fraction (SVF) and adipose-derived mesenchymal stem cell (ASC) injections also come with their own challenges. One study explains that “potential complications from liposuction limit the ability of SVF and ASC injections to replace existing minimally invasive treatments for knee osteoarthritis” (Han et al., 2025). So, even some of the latest therapies are not risk-free.

Professor Paul Lee, a cartilage expert and advisor at the Royal College of Surgeons of Edinburgh, advises that “the evaluation of risks should always be tailored to each patient’s unique health status and treatment goals.” This personalised approach is key.

Who Might Be at Greater Risk?

Certain groups are more likely to have complications from knee injections. This includes individuals with poorly controlled diabetes, existing joint infections, or allergies to injection ingredients.

Patients on haemodialysis or with weakened immune systems are typically considered higher risk, due to their susceptibility to infection. However, recent evidence suggests that with proper care, “intra-articular steroid injection is safe for dialysis patients” (Tabata et al., 2023), underscoring the importance of supervised treatment.

National guidelines from groups like the British Orthopaedic Association and the British Knee Society stress thorough screening for those at higher risk. This ensures that injections are as safe as possible.

Specialist clinics, such as MSK Doctors, provide detailed assessments and personalised advice to reduce risks and support patients at every stage of their treatment.

Alternatives and Recent Advances: Choosing the Best Path

Knee injections aren’t the only treatments available. Other options include physical therapy, medications, and surgery if needed.

More recent innovations include uncemented implants, which in specialist clinics have shown excellent results without the need for repeated injections. Bone cement remains important too, especially in certain trauma or cancer cases.

Biologic treatments like SVF and ASC injections are gaining attention. While these can improve pain and function better than some traditional treatments, “potential complications from liposuction limit their ability to replace existing minimally invasive treatments” (Han et al., 2025). So, while promising, these therapies are not without their risks.

Discussing all available options with your healthcare team is essential to find the treatment best suited to your individual needs and lifestyle.

Frequently Asked Questions (FAQ): Patient Safety and Making Decisions

Who should avoid knee injections?
People with active infections, uncontrolled diabetes, or allergies to injection components should generally avoid knee injections unless closely monitored by specialists.

How often can knee injections be safely repeated?
The frequency depends on the type of injection and individual health. Repeated treatments should be considered only under medical advice and regular review.

What signs indicate a complication requiring urgent attention?
Severe pain, increasing swelling, redness, fever, or discharge at the injection site are warning signs that need prompt medical evaluation.

How can risks of infection or allergic reaction be minimised?
Using sterile techniques, thorough screening beforehand, and selecting suitable patients helps reduce risks. Good communication with your healthcare provider is also vital.

Conclusion

Understanding both the benefits and risks of knee injections is essential when considering treatment for arthritis. Personalised care under expert guidance, such as from Professor Paul Lee and specialist clinics like MSK Doctors, helps ensure treatment is as safe and effective as possible. Always stay engaged in your care, ask questions, and seek balanced information to make well-informed decisions.

References

• Fucaloro, S. P., Bragg, J., Berhane, M., Mulvey, M., Krivicich, L., Zink, T. M., & Salzler, M. J. (2025). Complications of Platelet Rich Plasma Injection for Knee Osteoarthritis are Similar to Corticosteroids and Hyaluronic Acid, but are Significantly Greater than Placebo Injections: A Meta-Analysis of Randomized Controlled Trials. Arthroscopy. Advance online publication. https://doi.org/10.1016/j.arthro.2025.05.018
• Tabata, Y., Omori, S., Mitsuhashi, O., Enomoto, K., Sawano, Y., Murotani, N., Omori, K., Tabata, Y., & Majima, T. (2023). Comparison of Intra-articular Knee Injection of Corticosteroid between Hemodialysis and Non-hemodialysis Patients. JMA Journal. https://doi.org/10.31662/jmaj.2023-0020
• Han, J. H., Jung, M., Chung, K., Moon, H.-S., Jung, S.-H., Byun, J., & Kim, S.-H. (2025). Intra-Articular Stromal Vascular Fraction and Mesenchymal Stem Cell Injections Show Variable Efficacy and Higher Potential Complications Compared to Corticosteroid and Hyaluronic Acid in Treatment of Knee Osteoarthritis: A Meta-Analysis of Randomized Controlled Trials. Arthroscopy. Advance online publication. https://doi.org/10.1016/j.arthro.2025.01.050