The main components of the San Fu patch are the traditional Chinese medicine Gansui, white mustard seeds, pine and ginger, among which pine and white mustard seeds are more irritating to the skin. Many people have local itching after applying the San Fu patch as a sign of contact dermatitis, which is an allergy of the skin to the traditional Chinese medicine components in the San Fu patch, or perhaps to the adhesive of the San Fu patch. The itching is accompanied by erythema, papules or blisters on the itchy area, the boundary of the erythema is obvious and the shape of the Sanvu paste is basically the same, when the allergy is serious, there will be large blisters or even epidermal necrosis, ulcers, in addition to itching, there will be burning or swelling sensation. After the appearance of the above symptoms, you need to promptly take off the three volt paste, the epidermis residual Chinese medicine and mucilage clean, local can be used glucocorticoid cream, such as hydrocortisone butyrate cream or mometasone furoate cream and other topical, plus oral antihistamines, such as loratadine tablets and levocetirizine hydrochloride tablets. Do not scratch the skin during the attack to avoid bringing the allergens to other skin areas, and use a syringe to extract the blistering fluid from the skin if it is present. Don’t eat spicy, greasy, beef, mutton, seafood and other hairy products during the attack, don’t drink alcohol, and avoid the use of Chinese medicine with similar ingredients as Sanfu paste in the future.