For severe acne such as abscess type acne where medication is not effective, photodynamic therapy can be used, which is a more advanced method and a popular topic. The process of photodynamic therapy for acne is to first apply topical photosensitizing medication to the skin and seal the package for 3 hours, then irradiate the skin with a specific wavelength of light and a photochemical reaction occurs to produce damage to the tissue. Since the sebaceous glands absorb more of the drug than the skin, the photochemical reaction is heavier and the sebaceous glands are more heavily damaged. This results in an effective and long-lasting treatment for acne. However, there will be some side effects as follows, such as skin may be red and swollen for 2-7 days, and the existing pustules will be aggravated, but gradually they will subside and show the desired effect. The effect is rarely seen with skin burns. One treatment costs about 1000-2000 RMB. Usually 3-4 treatments are needed.