For many conditions a short course of high dose prednisone or similar oral corticosteroid therapy can lead to dramatic improvement. Examples of illnesses treated effectively with burst course of prednisone include croup, acute exacerbations of asthma and chronic bronchitis, many acute allergic reactions, acute attacks of gout, and numerous other acute inflammatory disorders.
Corticosteroids are very different from the anabolic steroids you read about being abused by athletes. Corticosteroids are produced in the adrenal cortex, and are important in regulation of the bodies inflammatory response and in regulation of carbohydrate, protein and fat metabolism.
The key to safely using short-term corticosteroid therapy is to keep the duration of therapy brief. Use of even moderate doses of steroids for over about 2 weeks can lead to a delay in the adrenal gland being able to produce adequate natural cortisol to support us in times of increased demand. This is not felt to be a problem with the usual short courses given most of the time. It is safer to use a high dose for a short time than a moderate dose for a longer period of time.
Some patients cannot tolerate high dose corticosteroids. Most side effects are temporary and not serious, including fluid retention, acid dyspepsia, and mild to moderate agitation or anxiety. Less common but more significant risks include psychosis, extreme insomnia or agitation, marked elevation of blood sugars in diabetic or pre-diabetic patients, and a very rare condition called aseptic necrosis of bone, usually the hip. There is also concern about suppression of the immune system and reactivation of latent tuberculosis in patients with a history of TB or a positive TB skin test.
The basic message though is that if you need to use prednisone a short course is usually safe and can be very effective. Longer courses are much more problematic, require careful monitoring by your physician and may need prolonged tapering of the drug.