Allergy causes redness, swelling and itching all over the body, usually due to allergic reaction caused by ingestion, inhalation or contact with allergens, when the symptoms are severe, the key to treatment is to stay away from allergens and give anti-allergy medication. First of all, in the case of redness, swelling and itching all over the body, and if the allergen is clear, avoid contact with the allergen again, and if it is caused by medication, stop using the medication and consult your doctor if you need to change the medication. At the same time, it is necessary to drink more water and urinate more often to promote the metabolism of drugs in the body, and can also apply cold saline locally to relieve the symptoms. Secondly, you need to use medication under the guidance of a doctor, mainly oral medication, commonly used drugs such as loratadine, cetirizine, epothilone, azulfidine, paracetamol, cyproheptadine and other antihistamines; if the respiratory system is involved, symptoms such as respiratory distress can be treated with glucocorticoids, such as prednisone (prednisone) as prescribed by the doctor. In addition, for the phenomenon of erythema and swelling, topical treatment with ointments such as glycolic lotion and tacrolimus can also be applied symptomatically. If the use of a drug is not effective, a combination of drugs can be used. Calcium gluconate can be used when the rash is extensive, supplemented with vitamin C IV treatment. In addition, during treatment, attention should be paid to local skin care, do not scratch the local skin to avoid causing infection.