eritema

Erythema is the redness of the skin or mucous membranes caused by increased blood flow in superficial capillaries. It results from vasodilation due to heat, inflammation, irritation, or other stimuli and is often accompanied by warmth and sometimes itching or pain. The redness may blanch (fade) when pressed, indicating superficial blood vessel dilation, though some conditions can show non-blanching redness.

Erythema is a nonspecific finding that appears in many settings. Physiologic flushing occurs with embarrassment, exercise, or cold exposure. Local erythema can arise from skin irritation, dermatitis, infection, or trauma. Sun exposure can cause erythema (sunburn), and certain medications or allergic reactions can produce drug eruptions or contact dermatitis with reddened patches. Chronic erythema can be seen in rosacea or autoimmune diseases, while specific named patterns, such as erythema marginatum, are associated with systemic conditions like rheumatic fever.

Diagnosis relies on history and physical examination, noting distribution, blanching, accompanying symptoms, and potential triggers. In uncertain cases, further evaluation may include laboratory testing or skin biopsy to distinguish erythema from other red skin conditions such as purpura or vasculitis.

Treatment targets the underlying cause. Removing irritants or allergens, sun protection, and symptomatic care (cool compresses, moisturizers, or topical corticosteroids for dermatitis) are common approaches. Infections require appropriate antimicrobial therapy, and drug-induced erythema often improves after stopping the offending medication. Most erythemas resolve with appropriate treatment or on their own, but persistent or unusual patterns may require specialist evaluation.