What to do during the first 48 hours

Ease a normal sore spell

Reduce hard activity while the knee feels sore. Easy movement may be fine if your directions allow it. Don't test the knee with a long walk. Give the joint time to settle.

A flare means extra soreness that briefly follows the shot. Cortisone hasn't started helping yet. The soreness should begin moving in the right direction. It shouldn't keep growing hotter and worse.

Notice what changes through the day. Write it down if that helps you remember. It'll make a later call much clearer. It also keeps you from guessing about when things began.

Watch blood sugar and other changes

Cortisone placed in a knee doesn't stay only there. Some can travel beyond the knee. Your face may feel warm and look red, and your sleep may change. Tell your other doctors about a recent shot.

If you have diabetes, cortisone can cause a short blood sugar rise. Follow the plan your doctor gave you. Don't change medicine from a website. Call if your readings or symptoms worry you.

Your health history matters before the visit for this reason. A treatment in the knee can still affect your body. Ask about these effects before the shot. The clinic should explain which changes need a call.

Get urgent help when the knee worsens

A knee that feels hot, looks swollen, and keeps worsening isn't a normal flare. Fever makes that concern stronger. Don't wait several days to see what happens. Get urgent medical care.

A joint infection is uncommon, but it can harm the knee. Clean skin and careful technique lower the risk. Quick care matters if infection signs appear. This warning is simple because delay can matter.

For ordinary soreness, follow the clinic's activity directions. Keep movement gentle until the knee settles. If you're unsure about a change, call and describe it plainly.

Sources

1. A 2024 AJR review of corticosteroid injection side effects lists local effects (post-injection flare, skin hypopigmentation and atrophy, infection, tendon rupture, accelerated osteoarthritis progression, osseous injury) and systemic effects (adrenal suppression, facial flushing, hypertension, hyperglycaemia, osteoporosis), and calls for targeted pre-injection counselling for specific populations.

   Kamel SI, et al. — Local and Systemic Side Effects of Corticosteroid Injections for Musculoskeletal Indications.. AJR Am J Roentgenol, 2024. DOI: 10.2214/AJR.23.30458.

2. A review of systemic absorption after locally injected glucocorticoid found substantial individual variability, and established that both intra-articular and epidural injections can produce systemic effects lasting WEEKS - while noting there are no guidelines addressing systemic absorption or overall systemic risk.

   Stout A, et al. — Systemic Absorption and Side Effects of Locally Injected Glucocorticoids.. PM R, 2019. DOI: 10.1002/pmrj.12042.

3. A review of ten studies found single local corticosteroid injections caused a significant but TRANSIENT rise in blood glucose in patients with diabetes, with no adverse reactions or complications reported, and concluded such injections are most likely safe in people whose diabetes is well controlled.

   Waterbrook AL, et al. — Blood Glucose Levels After Local Musculoskeletal Steroid Injections in Patients With Diabetes Mellitus: A Clinical Review.. Sports Health, 2017. DOI: 10.1177/1941738117702585.

4. A 2017 MMWR outbreak report describes 41 cases of septic arthritis following intra-articular injections given during 250 patient visits at a single New Jersey outpatient practice, 30 (73%) of whom needed surgery; recovered organisms were oral flora and the investigation found multiple breaches of infection-prevention practice.

   Ross K, et al. — Outbreak of Septic Arthritis Associated with Intra-Articular Injections at an Outpatient Practice - New Jersey, 2017.. MMWR Morb Mortal Wkly Rep, 2017. DOI: 10.15585/mmwr.mm6629a3.

5. The 2015 Cochrane review of 27 trials (1,767 participants) found intra-articular corticosteroid better than sham for knee OA pain (SMD -0.40, 95% CI -0.58 to -0.22; NNTB 8), but the benefit decayed with time: moderate at 1-2 weeks, small at 13 weeks, and no evidence of any effect at 26 weeks. All outcomes were graded LOW quality.

   Jüni P, et al. — Intra-articular corticosteroid for knee osteoarthritis.. Cochrane Database Syst Rev, 2015. DOI: 10.1002/14651858.CD005328.pub3.