How might a postinjection flare be distinguished from infection after a Glucocorticoids injection?
Postinjection flares occur in 1% to 2% of patients receiving GC injections and are most likely to occur with use of least soluble (i.e., longest-acting) GC preparations. Injections of the lateral epicondyle of the elbow are particularly prone to this complication. The flare occurs within 6 to 18 hours after an injection. In contrast, an infection usually becomes apparent 2 to 4 days after an injection. If need be, the joint can be aspirated and will show intracellular steroid crystals in a postinjection flare (look like calcium pyrophosphate dihydrate crystals but polarize with first-order red compensation-like gout crystals). Treat with ice, NSAIDs, and pain medications. A postinjection flare should resolve within 24 hours, whereas an infection will not.
