Cortisone is not a pain relieving medication, it only
treats the inflammation. When pain is decreased from cortisone it is because the
inflammation is diminished. 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 is a type of steroid that is produced naturally by a gland in your body called the adrenal gland. Cortisone is released from the adrenal gland when your body is under stress. Natural cortisone is released into the blood stream and is relatively short-acting. Injectible cortisone is synthetically produced and has many different trade names (e.g. Celestone, Kenalog, etc.), but is a close derivative of your body's own product. The most significant differences are that synthetic cortisone is not injected into the blood stream, but into a particular area of inflammation. Also, the synthetic cortisone is designed to act more potently and for a longer period of time (days instead of minutes).
Many conditions where inflammation is an underlying problem are amenable to cortisone shots. These include, but are certainly not limited to
The shot can be slightly painful, especially when given into a joint, but in skilled hands it usually is well tolerated. Often the cortisone injection can be performed with a very small needle that causes little discomfort. However, sometimes a slightly larger needle must be used, especially if your physician is attempting to removed fluid through the needle prior to injecting the cortisone. Numbing medication, such as Lidocaine or Marcaine, is often injected with the cortisone to provide temporary relief of the affected area. Also, topical anesthetics can help numb the skin in an area being injected.
Typical Injection sites for the foot.
Probably 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. This usually lasts a day or two and is best treated by icing the injected area. 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.
Other side-effects of cortisone injections, although rare, can be quite serious. The most concerning 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.
Because cortisone is a naturally occurring substance, true allergic responses to the injected substance do not occur. However, it is possible to be allergic to other aspects of the injection, most commonly the betadine many physicians use to sterilize the skin.
There is no rule as to how many cortisone injections can be given. Often physicians do not want to give more than three, but there is not really a specific limit to the number of shots. However, there are some practical limitations. If a cortisone injection wears off quickly or does not help the problem, then repeating it may not be worthwhile. Also, animal studies have shown effects of weakening of tendons and softening of cartilage with cortisone injections. Repeated cortisone injections multiply these effects and increase the risk of potential problems. This is the reason many physicians limit the number of injections they offer to a patient.