To describe the natural history of a condition or disease. To describe the natural history of a condition or disease. To determine effectiveness or cost effectiveness of treatments/services and/or health care products. To measure or monitor safety and harm. To measure quality of care.
According to the NMSS, attacks or flare-ups of symptoms only qualify as exacerbations if: 1  they occur at least 30 days from an earlier flare-up. 2  symptoms last for 24 hours or longer.
However, the most common cause of these symptoms is a reaction to the injected steroid (âsteroid flareâ) which occurs in 2 to 5% of patients. A âsteroid flareâ usually begins 6-12 hours after the injection and may last for 2-3 days. Regardless of the cause, it is important to see a physician with these symptoms.ost injections typically take 24-48 hours to take full effect. If local anesthetic was given with the steroid injection, you may feel improvement relatively quickly. The duration of improvement varies.