What is cortisone?

Cortisone is a substance similar to a natural steroid hormone produced by the body. It reduces pain, heat, redness and swelling of joints and their surrounding structures. Special preparations are used to prolong its effect at the site of injection. Cortisone starts to act slowly over 24-36 hours and the beneficial effects may last for days or months.

When is a cortisone injection given?

• when pain due to inflammation is severe either in a joint or the surrounding structures
• if only a few joints are involved
• if specific joints are preventing activity
• if other medication cannot be used
• local anaesthetic may also be given. This relieves pain immediately and lasts for 3-4 hours while cortisone is beginning to work.

How often are cortisone injections given?

Discuss this with your doctor, but as a general rule:

• in a joint, no more than once a month, with a maximum of three or four cortisone injections in one year
• in the surrounding structures, no more than once every two or three weeks.

Low, well-spaced doses of injected corticosteroid are thought to produce little risk of significant side effects.

What are the benefits of cortisone injections?

• pain and swelling are reduced
• mobility is increased
• often, as the pain settles, other medications can be reduced
• it may be combined with other treatment such as physiotherapy.

The injection procedure

The method of adminstration of the injection into a joint is similar to that of soft tissue injections. Before injection a separate syringe and needle is used to remove any excessive amount of fluid that is in the joint. Your doctor is then able to examine the fluid and send a sample to the laboratory for diagnosis. The reduced pressure of the fluid in the joint also relieves the pain and may help the joint to heal.

After treatment with cortisone injections

To prolong the action of the cortisone in the joint or surrounding structures, it is important to:

• rest the joint for about 24 hours
• avoid excessive movement or stress on the joint for about one week. Sometimes there is increased pain after injection which settles within 24 hours
• if there is pain you should rest, apply ice and take aspirin or paracetamol
• if the pain worsens over 48 hours and/or you feel unwell, contact your doctor without delay.

Side effects

As cortisone is injected infrequently into a specific site, very little enters the bloodstream compared with cortisone taken in tablets. Because of this, 'cortisone side effects' are minimal. However, other joints may temporarily improve as the cortisone slowly enters the blood stream.

Cortisone side effects are very uncommon. They include:

• flushing
• swelling of fingers or face (oedema)
• menstrual irregularity
• mood changes
• raised blood pressure
• thinning (atrophy) or altered colour of the skin at the site of the injection. This rarely occurs with joint injection, but may with injections of surrounding structures, eg. tennis elbow
• raised or unstable blood glucose levels in diabetics for several days following injection.

See also: Medications for arthritis

Original material supplied by Arthritis New Zealand. Edited by everybody, July 2005.