Is It Normal for Pain to Get Worse Before It Gets Better After Stem Cell Therapy?

Short answer

Often, yes — a temporary “flare” of increased pain, swelling, or stiffness in the days after a joint injection is a recognized and fairly common response, and it isn’t necessarily a sign that anything went wrong. That said, there’s an important difference between an expected flare and a warning sign that needs medical attention, and it’s worth knowing which is which before your procedure.

Why a flare happens

Injecting cells (or PRP) into a joint introduces a local inflammatory and healing response on purpose — that response is part of how the tissue-repair process is thought to start. On top of that, the needle itself causes minor trauma to the tissue. Between those two things, it’s common for the treated area to feel more irritated before it starts to feel better, rather than improving in a straight line from day one. This “flare response” pattern is documented for orthobiologic injections generally, including in peer-reviewed research on intra-articular PRP injections.

What a normal flare typically looks like

• Onset: Usually within the first 24–72 hours after the injection.
• Duration: Commonly resolves within one to two weeks; some patients report it lingering longer, into the six-to-eight-week range, before they notice clear improvement.
• What it feels like: Increased soreness, stiffness, warmth, or mild swelling localized to the treated joint — generally trending toward better, even if slowly, rather than steadily worse.

What actually helps during a flare

• Rest the joint more than usual for the first several days.
• Ice, applied as your provider recommends, can help with comfort.
• Ask before taking anti-inflammatories. Some physicians advise against NSAIDs right after treatment, since they may blunt the inflammatory response the therapy is trying to trigger — this is a question for your treating physician, not something to decide on your own.
• Give it time. A flare that’s easing week over week, even slowly, is generally the expected pattern — not a reason to panic on day 3.

When it’s not a normal flare

Contact your treating physician promptly if you notice:

• Pain that keeps getting worse past the two-week mark instead of plateauing or easing
• Redness or warmth that’s spreading, rather than staying localized to the injection site
• Fever, chills, or feeling generally unwell
• Severe, unrelenting pain that isn’t responding to rest

These aren’t typical of a normal post-injection flare, and a physician should evaluate them directly rather than you trying to judge it from an article online.

Frequently asked questions

How is a normal flare different from an infection?

A flare is generally localized soreness, stiffness, or mild swelling that trends toward improvement, without fever or spreading redness. An infection more often comes with fever, spreading warmth/redness, or pain that keeps escalating rather than easing — see our full breakdown of real risks and red flags →.

Does everyone experience a flare?

No — patient reports vary widely; some notice a flare, others don’t notice much of anything unusual after the procedure. Neither pattern by itself tells you whether the treatment is “working.”

If I have a flare, does that mean the treatment is working better?

Not necessarily — a flare reflects the local inflammatory response to the injection itself, not a guarantee of your eventual outcome. For a realistic sense of when results typically appear, see how long stem cell therapy results take →.

Should I take time off work or activities after treatment?

That depends on your specific procedure, the joint treated, and your physician’s guidance — ask during your evaluation so you can plan your trip and recovery time accordingly.

Further reading

• Post-Treatment Care: What You Should Do After Stem Cell Injection — Avid Sports Medicine
• Effects of intra-articular PRP injections — peer-reviewed, National Institutes of Health (NIH)

Not sure what to expect for your specific case?

A physician who’s actually evaluated you is the right person to tell you what’s normal for your situation — not a generic article. Get your free evaluation →