There are multiple conditions to consider for a red nose. First, consider rosacea, which is also considered to be rosacea, and is often clinically manifested as dilated capillaries on the nose and bilateral cheeks, where papules and pustules can sometimes be seen, and its pathogenesis may be related to infection, endocrine and impaired skin barrier function. Secondly, it is considered to be allergic dermatitis, which manifests as localized edematous erythema with pruritus. Its pathogenesis is related to allergic reactions induced by certain stimuli, such as cosmetics, skin care products, pollen, drugs, food, dust mites, etc. In addition, systemic lupus erythematosus is considered. Systemic lupus erythematosus can manifest as perinasal butterfly erythema, which can be accompanied by hair loss and photosensitivity, and its pathogenesis is related to immune factors, genetic factors and infection factors.