Corticosteroids are widely used in otolaryngology to treat many disorders; however, the nature and extent of possible complications may not be completely understood. A comprehensive review of the physiology of systemic corticosteroids and literature discussing the known side effects associated with their use is presented. The pathophysiology and the clinical impact of these side effects are reviewed. There are various potential side effects from the use of corticosteroids. Practitioners using corticosteroids should be familiar with these and obtain the patient's informed consent when appropriate.