Allergic skin diseases account for a significant proportion of dermatology outpatient clinics and mainly include drug rash, contact dermatitis, eczema, and urticaria. The skin manifestations of these diseases become diverse, and can manifest as erythema, papules, blisters, wind-blister, nodules, lichenoid lesions, etc., with pronounced itching. The etiology of drug rash is clear and is caused by drug allergy. The etiology of contact dermatitis is also clear, mainly caused by contact columns such as rubber cream, cosmetics, etc., and the trigger must be removed during treatment. The causes of eczema and urticaria are more complex. Common internal causes include chronic infectious lesions, chronic digestive system diseases, endocrine and metabolic disorders, and mental factors; common external causes include food, inhalation of pollen, paint, various animal hides, plants, and chemical substances. Patients should avoid scratching the lesions to prevent infection; do not scald with soap and hot water; avoid possible causative factors such as drugs, cosmetics, allergenic foods (nuts such as peanuts, chestnuts; proteins such as seafood, beef, mutton; mushrooms such as shiitake mushrooms, etc.). Commonly used treatments include oral antihistamines, vitamin C, calcium, topical corticosteroids, and adjunctive herbal treatments. Allergen testing is feasible for patients with recurrent chronic urticaria to help clarify allergens for more effective prevention and treatment.