Which of the following is a common symptom of erythema?

Redness is a defining characteristic of erythema, which is the medical term for an increase in blood flow to the skin, leading to a visibly red appearance in the affected area. This symptom is commonly associated with various conditions, such as inflammation, infection, or allergic reactions, where the blood vessels expand, causing capillaries to fill with more blood.

While swelling, itching, and pain can also accompany erythema depending on the underlying condition, they are not intrinsically linked to the condition itself. Redness is primarily what distinguishes erythema from other skin responses, making it the most straightforward and recognized symptom.