Cortisone is a corticosteroid released by the adrenal gland in response to stress and is a potent anti-inflammatory agent. Artificial preparations containing cortisone are injected directly into the affected joint to relieve pain and reduce inflammation. The effects may last for several weeks and cortisone injections are recommended in injuries that cause pain & inflammation and those don't require surgical treatment. One such condition frozen shoulder and cortisone injection into shoulder joint relieves pain & inflammation.
Cortisone injections offer significant relief in pain & inflammation however is associated with certain adverse effects. The most common side effect is a "cortisone flare", a condition where cortisone crystallizes and cause severe pain for a brief period that lasts for a day or two. Cortisone flare can be minimized by applying ice to the injected area. Other adverse effects include whitening of the skin and infection at the injection site, a transient elevation in blood sugar in patients with diabetes.