Children with large flat bumps on the body, may be due to urticaria, you can use topical medication, oral medication and so on. 1. topical medication: you can apply local glycerine lotion, with astringent and anti-itching effect. 2. Oral drug treatment: you can take antihistamines, commonly used drugs are cetirizine granules, loratadine oral solution, etc., with the role of anti-allergic itching. If there is chest tightness, dyspnea, abdominal pain and other symptoms, you need to immediately consult the doctor, to be systematic use of glucocorticoids and other drug therapy. These drugs above can have adverse reactions such as dizziness, drowsiness, skin irritation, etc. When using them, they need to be used under the guidance of a doctor.