Even though topical corticosteroids such as creams or ointments are applied to the surface of the skin, they can still cause side effects . Long-term use or excessive use can lead to thinning of the skin, irritation, dryness, or changes in skin color. If your doctor recommends that you occlude your psoriasis areas -- wrapping them in plastic after applying a topical corticosteroid to boost the effect -- side effects may be more common. More serious side effects may occur with topical corticosteroids if used in high doses for prolonged periods. You may become resistant to the helpful effects of topical corticosteroids over time, too.