Skin diseases are mostly found on the surface of the body, and topical medicines are easy to be effective as they go straight to the place where the disease is found. The external treatment of skin diseases has a long history. Topical application of medicated water is a common method used in our department to treat facial dermatitis, atopic dermatitis, eczema, psoriasis, acne and other skin diseases. And the correct use is the key to ensure efficacy and avoid adverse reactions. Tips to know before use: 1, any topical drugs can not guarantee 100% safety for all patients without stimulation, especially for facial dermatitis or skin sensitivity. Such patients should be more cautious and careful before using topical drugs or skin care products. 2, the first 3 days of the first small area trial (skin allergic reactions generally appear within 72 hours after use), if the local redness, swelling, heat, pain, itching and other uncomfortable symptoms, indicating that the trial of the drug is allergic to the drug should be discontinued immediately. 3, allergic reactions should be timely cleaning of the skin, at the same time, cold water or ice water can be used to apply external compresses to the lesions, each time for 15-30 minutes, can be repeated several times, if there is no significant improvement, please go to the hospital in a timely manner. The method of external application: 1, the mask paper cut into small pieces (such as 2 × 2cm or diameter of 2cm or so), or a small piece of gauze (Note: mask paper is mostly used for facial lesions, the use of 1 layer can be; gauze is mostly used for trunk and limb lesions, to 6-8 layers appropriate), with the drug water will be soaked to the degree of non-dripping, and then applied externally on the skin lesions. 2, 15-30 minutes each time (can be packed in a small spray bottle beforehand, if you feel that the humidity is not enough during the external application, you can spray the appropriate amount). 3, 2-3 times a day, after the compress can be washed with water, to be completely dry before the moisture external moisturizing skin care products or ointment. 4.If there is no discomfort after 3 days of external application, you can gradually expand the area of external application. 5, the remaining potion after sealing in the refrigerator to be used, if the potion discoloration or deterioration, then stop using.