1.Search for the cause of allergy Take a detailed medical history and carefully inquire about the environment related to the onset of the disease, the type, quantity, physical and chemical properties of the substances exposed, the duration of exposure, the mode of exposure, and whether there were similar rashes in the past. From the history, we can analyze which substance may be related to the rash and provide a basis for the skin patch test. Once the cause of the allergy is found, try to avoid re-exposure. Irritants or toxic substances left on the skin should be rinsed off as soon as possible, using water, saline or light soapy water. If the contact is a strong acid, use a weak alkaline liquid to rinse (such as soda); if it is a strong alkaline substance, use a weak acidic liquid to rinse (such as boric acid solution). 2. Avoid stimulation When clinical symptoms appear, local stimulation should be minimized. Avoid scratching, scalding with hot water, strong sunlight or hot wind stimulation. 3, systemic treatment Internal antihistamines, such as cyproheptadine, diphenhydramine, chlorpheniramine, avastine, cetirizine, imipramine, epastine, desloratadine, etc.; high-dose vitamin C oral or sedative; 10% calcium gluconate injection, intravenous push. If the area is extensive and the vesicles and exudates are serious, glucocorticoids can be given. Such as oral prednisone, trenbolone or dexamethasone; Depo-Provera intramuscular injection. In severe cases, hydrocortisone or dexamethasone can also be used intravenously and then maintained orally after the symptoms have subsided. If contact dermatitis is combined with local infection, such as lymphangitis, lymphadenitis, soft tissue inflammation, antibiotics can be used, the lighter given roxithromycin, penicillin V potassium, cephalexin or sulfonamides orally; the heavier given intravenously with penicillin, cephalosporin or quinolone antibiotics. 4.Local treatment Local treatment is very important and should be treated separately according to clinical manifestations. Acute stage For erythema and papule, use lotion, cream or ointment. Such as furnace glycolate lotion, oscillating lotion, tretinoin cream, clofloxacin cream, skin relaxation cream, etc., can also use ointment containing pine distillate oil, branched distillate oil, zinc oxide for external application. Erythema is obvious, with blisters, vesicles and exudate can do open cold wet dressing, wet dressing solution has 3% boric acid solution, 1:2 aluminum acetate solution, 1:8000 potassium permanganate solution. If you have purulent discharge, use 0.02% furacilin solution or 0.5% ezacrine solution wet dressing. Wet dressing should not be too long, usually wet dressing 2-3 days, when the exudate stops, swelling subsides, you can stop wet dressing, switch to cream or ointment topical application. Sub-acute or chronic stage The cream and ointment are mainly used externally, corticosteroid ointment, pine distillation ointment, black bean luting ointment, zinc oxide ointment, etc. If there is purulent secretion, antibiotics such as neomycin, erythromycin, bacitracin, or other antiseptic agents such as mupirocin ointment, safranin, mercury agent, etc. can be added to the ointment.