Physicians frequently use cortisone injections to help reduce inflammation in or around tendons and joints . The medication that is injected is usually a local anaesthetic such as Lignocaine or Marcain in combination with a synthetic form of cortisone (Celestone). There are two reasons for this combination .
1. Pain relief from the injection itself. Lignocaine lasts for about 1 hour and Marcain lasts for about 4 - 5 hours after the injection.
2. As a Test . If the discomfort is completely relieved by the Lignocaine or Marcain, this suggests that the injection has been placed in the correct location.
The cortisone is mixed with a special carrier , so that it stays in the place where it was injected. Therefore, injections in one finger or part of your body do not "count" when deciding whether or not to have an injection in another finger or part of the body. Because the carrier restricts the cortisone to the area of the injection, usually there are no general effects to the body from the cortisone such as would be expected if cortisone was taken by mouth.
In general only 1-3 injections are used in a given area, especially around tendons. If a joint injection provides prolonged relief (e.g. 6 months) then it is perfectly reasonable to repeat these injections on multiple occasions.
The effect of the cortisone, which is to reduce swelling and provide pain relief may take 24-48 hours to take effect.
The duration of action of cortisone is very variable but it usually works for about 1-2 months . Often by that time the problem which caused the irritation around the tendon or joint has resolved. If not, then there may be a recurrence of the original discomfort and a second injection might be necessary.
After the local anaesthetic wears off, the injection area will ache as any injection would. This usually lasts for a day or so and then as the cortisone starts to work, the discomfort goes away.
2. Tissue Damage
Multiple injections in the same area should be avoided because although the cortisone does reduce swelling and provide pain relief, it has also been shown to cause some damage to the tendons and joints after multiple injections in the same spot.
Allergic reactions or side effects to the medications which are injected are rare. Local reactions to the injection are slight and should be limited to local tenderness and perhaps some redness and swelling for the first day. The pain should not be more than that easily relived with aspirin or Panadol . Report any pain, redness or swelling in excess of that described above to your doctor immediately. Although extremely rare, infection is possible following a cortisone injection.
4. Skin Colour Changes
Injections close to the skin may cause changes in skin colour (either an increase or decrease in skin pigmentation ). Occasionally this change may be permanent.
Other reactions are extremely rare. It is possible to cause damage to structures during the needle insertion. Occasionally a skin nerve is irritated but this usually settles with time and massage of the area.