The side effects of drug O, which is the immunosuppressant nabulizumab injection, mainly include immune-related adverse reactions, infusion reactions, fatigue, and gastrointestinal reactions. 1. Immune-related adverse reactions include immune pneumonitis, colitis, hepatitis, nephritis and renal dysfunction, skin inflammation such as rash, itching and so on. 2. Infusion reactions include allergic reactions and febrile syndromes requiring hormone therapy. 3. Symptoms such as fatigue and weakness are common adverse reactions to this product. 4. Gastrointestinal reactions such as nausea and diarrhea are common adverse reactions to this product. Therefore, it is forbidden for people who are allergic to this product. This drug needs to be used under the guidance of a doctor and closely observed during the use of the drug.