The main effect of tacrolimus is to suppress the immune system, and its side effects include allergic reactions and other adverse reactions. 1. Efficacy: Tacrolimus is a potent immunosuppressant, which inhibits the expression of a variety of cytokines and inflammatory mediators by binding to T-cells, thus producing a powerful anti-inflammatory effect. It also produces immunosuppressive effects and can promote the synthesis of skin collagen and the recovery of skin barrier function. 2. Side effects: Tacrolimus may produce side effects after use, if the patient is allergic to the drug, it may lead to urticaria, laryngeal edema, respiratory difficulties and so on. In addition to this, patients may also experience adverse reactions such as constipation, diarrhea, gastrointestinal perforation, hypertension, alopecia, and anemia. If a patient is allergic to any of the ingredients in tacrolimus, it is recommended to prohibit the use of such drugs. As well as patients suffering from congenital QT syndrome or concomitant malignant tumors are prohibited. If the above symptoms occur, it is recommended to stop the drug immediately and go to a specialized hospital immediately for symptomatic treatment under the guidance of a doctor, and it is not recommended to use the drug blindly on your own.