Photodynamic action refers to the function or morphological change of organism cells or biological molecules under the action of light with the participation of photosensitizers, which leads to cell damage and necrosis in serious cases, and this action must have the participation of oxygen, so it is also called photosensitization-oxidation, which is called photosensitization in chemistry and photodynamic action in biology and medicine, and the method of treating diseases with photodynamic action. is called photodynamic therapy. The dermatology department mainly uses this treatment technology to treat condyloma acuminata, especially those that recur and grow in the urethra and vagina, with positive results. In addition, photodynamic therapy is effective in treating acne, Bowen’s disease, Bowen-like papulosis, squamous carcinoma, and basal carcinoma. Possible side effects after photodynamic therapy: erosion, exudation, edema, hyperpigmentation, slight pain, etc. Precautions and care after photodynamic therapy: 1. Keep local clean and dry. 2, urethral opening (inside) photodynamic therapy should drink more water and urinate more, so as to avoid urethral adhesion, the foreskin should quickly turn down the foreskin after treatment to prevent ingrowth. 3, facial flat warts treatment should do a good job of sunscreen measures to reduce hyperpigmentation. 4, during the treatment avoid eating cattle, mutton, dog meat, spicy stimulating food and hair products, do not smoke and drink. 5, perianal photodynamic therapy after treatment of more fruits and vegetables, to keep bowel movements, to avoid constipation. 6, during the treatment of condyloma acuminata sexual life is strictly prohibited, pay attention to personal hygiene, underwear changed after ironing and separate from the clothing of others. 7, pay attention to observe whether there is a recurrence, once the recurrence of timely consultation. 8, other rare side effects. Welcome patients to the hospital consultation and treatment.