Updated May 25, 2014.

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

Question: Cortisone Injection - Why Does Effectiveness Vary?

Injecting steroids (sometimes called "local" cortisone injection) into one or two specific areas of inflammation allows the doctor to deliver a high dose of medication directly to the bothersome area. When doctors give steroids orally or intravenously, they can not be certain that enough steroid medication will reach the problem area. Can the doctor be sure that the cortisone injection will work, since effectiveness varies?

Answer:

Cortisone Must Be Given Appropriately

Doctors often inject cortisone-type medications into painful, damaged joints. Single injections can relieve pain and swelling and appear to be safe, but repeated injections given too soon or too often can damage joints and delay healing.

When Cortisone Injection Done Safely, Benefit Is Huge

Since people can be crippled by arthritis, and a single cortisone injection into a damaged knee joint, for example, can allow an arthritic to walk without pain for many weeks -- cortisone-type drugs continue to be used to reduce swelling, lessen pain, and allow patients to return to normal daily activities.

Rule of Thumb for Cortisone Injection

Cortisone injections vary, and both short and long acting preparations are used, depending on the patient's needs. The duration of effectiveness depends on the type of cortisone injected, and how long the patient rests the joint after injection. A good general rule to follow is to give no more that 2-3 injections into the same joint in any given year, and ideally, rest the joint for 1 week after each injection.

_{Answer provided by the late Dr. Raymond Federman, a respected rheumatologist.}