In general, steroid injections are given with a local anesthetic, usually Lidocaine, to help control inflammatory reaction in bursae, around tendons, ligaments, and in joints. The local anesthetic will usually cause numbness to the injected area for several hours. If a long-acting anesthetic, such as Marcaine, is used, its effect may remain  up to 6-8 hours. The steroid in the injection will become effective in 2-3 days and may last for several weeks to months or may resolve the problem completely. The effectiveness for relief of pain and inflammation in steroid injections is not always predictable.