Erythema << `ehr` uh THEE muh >> is a redness of the skin. It is related to an increase in the amount of blood present in the capillaries (small blood vessels) of the skin. The skin reacts to slight injury or irritation with erythema, which can be produced in many ways. For example, exposure of the skin to sunlight for a short time will cause erythema. Longer exposure results in the formation of blisters. A sharp slap will also produce erythema in the contacted area. Erythema is also a symptom of some diseases.
