Corticosteroid drugs such as prednisone are commonly used to treat inflammatory bowel disease (IBD) and many other inflammatory conditions. These drugs are frequently prescribed because they are inexpensive and often work quickly to squelch inflammation. However, prednisone and most other steroid drugs do have several side effects.
One of the more visible effects of longterm use of high dosages of prednisone is "moon face," or swelling in the cheeks and neck. It happens because prednisone may cause weight gain and redistribution of fat deposits, with fat winding up in the face, abdomen, and the back of the neck. This can be a very difficult side effect to deal with because it often makes people feel unattractive and unhappy at a time when they are already feeling ill. Despite its effect on appearance, it's not medically dangerous, although medically dangerous side effects of prednisone certainly do exist.
Some of the side effects of prednisone can best be avoided by minimizing the dose as much as possible with the help of your physician. The facial roundness will typically decrease once the steroid is tapered down and discontinued.
Fusco RD. "All About Prednisone." GIHealth.com 2010. 20 Oct 2010.