Your body naturally makes its own cortisone when your body is under stress this is called cortisol. It is a type of steroid that is produced naturally by your adrenal gland and is released when your body is under stress.
Injectable cortisone is synthetically produced but is very similar to that produced by your body. The
injectable cortisone is injected into the affected area or joint. The injectable cortisone is typically long acting over several weeks or months. Cortisone is a strong anti-inflammatory medication. Cortisone only treats the inflammation. When pain is decreased from cortisone it is because the inflammation is decreased. By injecting the cortisone into a particular area of inflammation, very high concentrations of the medication can be given while keeping potential side-effects to a minimum. Cortisone injections usually start to work within 2 days to a week, and the effects can last for up to several months. Many times once the inflammation is gone, the pain will stay away.
Many conditions where inflammation is an underlying problem are amenable to cortisone shots. These include, but are certainly not limited to:

• Shoulder Impingement
• Partial rotator cuff tear
• Calcific tendonitis
• Arthritis of the shoulder, hip, knee or spine
• Tennis or golfers elbow
• Bursitis of the knee or hip
• Plantar fascitis
• Trigger points
• Trigger finger
• Carpal tunnel
• Back pain, neck pain

The shot can be slightly painful, especially when given into a joint, but is usually well tolerated. Also, topical anesthetics can help numb the skin in an area being injected. The most common side-effect is a ‘cortisone flare,’ a condition where the injected cortisone crystallizes and can cause a brief period of pain worse than before the shot. It usually lasts a day or two and is best treated by icing the injected area and taking an oral anti- inflammatory. . Another common side-effect is whitening of the skin where the injection is given. This is only a concern in people with darker skin, and is not harmful, but patients should be aware of this. Some patients will have flushing of the face that can last for hours to a couple of days and then will resolve. The most concerning risk of an injection, is infection, especially if the injection is given into a joint. The best prevention is careful injection technique, with sterilization of the skin using iodine and/or alcohol. Also, patients with diabetes may have a transient increase in their blood sugar which they should watch for closely.