The differential diagnosis of facial redness includes: dermatologic conditions of rosacea, acne, seborrheic dermatitis, externally triggered reactions such as allergic contact dermatitis, irritant contact dermatitis, and photo allergic reactions, and infections such as erysipelas and viral exanthems, and systemic diseases including lupus erythematosus and dermatomyositis, and polycythemia.
Seborrheic dermatosis is suggested by erythematous patches with greasy, yellow scale.
Geometric, erythematous, edematous scaly plaques suggest allergic contact dermatitis.
In the presence of pulmonary symptoms, systemic erythematous lupus and dermatomyositis are considered.
Rosacea is considered particularly if the central face is affected and it flares up with alcohol, spicy food, or heat.