Cortisone is a potent anti-inflammatory agent. Artificial preparations containing cortisone are injected directly into the affected knee to relieve pain and reduce inflammation. Cortisone injections are recommended to treat knee pain and inflammation in mild to moderate arthritis, and in patients that are not surgical candidates. The effects may last from a few weeks to several months. Adverse effects from cortisone injections are rare, and include 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 infection in the joint and a transient elevation in blood sugar in patients with diabetes. Following a cortisone injection, it is recommended that knee replacement surgery be delayed for a few months to avoid increased risk of post-operative infection.