The toxic side effects of photodynamic therapy can be considered minimal, and its main adverse reaction is photoallergic reaction. However, we use topical application of photosensitizers to minimize the risk of systemic use of photosensitizers, and topical application of photosensitizers to enhance light exposure is more targeted to treat diseases located on the local skin surface, such as condyloma acuminata, acne, Bowen-like papulosis, etc. The effect is remarkable. Of course, within a few days after treatment, patients may experience temporary localized reactive edema at the treatment site, which generally varies depending on the specific treatment site and condition, but in general is not serious and the side effects are mild and easily relieved by routine treatment if they occur. Patients are generally easy to accept.