Allergic dermatitis is a large group of allergy-related skin diseases, and rosacea is a chronic inflammatory skin disease with differences in causes, symptoms, and treatments. 1. Causes: Atopic dermatitis is usually a collective term for urticaria, eczema, contact dermatitis, and other allergic skin diseases, and is thought to be related to factors such as abnormal immune function and skin barrier dysfunction. The cause of rosacea is not clear, but may be related to genetics, abnormal neurovascular regulation, infection, and so on. 2. Symptoms: Allergic dermatitis is characterized by a variety of lesions, such as erythema and papules, usually accompanied by itching. Rosacea is characterized by persistent erythema and dilated capillaries. 3. Treatment: atopic dermatitis treatment is based on oral antihistamines, topical glucocorticoids, rosacea treatment is more complex, can be used externally azelaic acid, calcium-modulated phosphatase inhibitors such as tacrolimus and other drugs, oral minocycline and other antibiotics. These are some of the differences between atopic dermatitis and rosacea, the specific differential diagnosis needs to be carried out by a professional doctor, it is recommended to go to the hospital, a clear diagnosis, and follow the doctor’s instructions for treatment.