If the plaster is applied for 5-10 days as a course of treatment, the effect of the plaster is not clear if the time is too short, if the plaster is too long it is easy to cause more or less skin damage. Light damage will appear local skin lesions or pain, more serious damage may appear allergic inflammation of the skin, redness, itching, pain and other situations, serious will also lead to skin ulceration, but these are for the general ointment, such as indomethacin Babu cream, pain relief cream or compound Nanxing pain cream and other ointments. For black ointment, such as the commonly used dog skin cream, the course of paste is between 15-30 days, each paste are paste 3-4 days, every 3-4 days to change. 5-7 tablets for a course of treatment, so the course of black ointment are between 15-30 days.