Corticosteroids are one of the most useful and commonly prescribed drugs in oral medicine practice. They are hormones of the adrenal cortex with strong anti-inflammatory and immunosuppressive effects. Topical and systemic corticosteroids are used in the treatment of many diseases with oral mucosal manifestations such as oral lichen planus (OLP), pemphigus vulgaris (PV), pemphigoid, and systemic lupus erythematosus (SLE), as well as in the treatment of chemical injuries, traumatic lesions, recurrent aphthous ulcers (RAU), and many other. Rarely occurring side effects of topical steroid therapy are oral candidiasis and mucosal atrophy. Side effects occur more often with the systemic use of corticosteroids, such as adrenal insufficiency, hypertension, diabetes, infection, glaucoma, and osteoporosis. However, despite various side effects, corticosteroids still remain irreplaceable in the treatment of numerous diseases and conditions.