The Daratumumab 400 mg Injection is used to treat cancer of plasma cells which is multiple myeloma. The injection is given intravenously into the body under the supervision of a healthcare professional. It is recommended to take the dosage as advised by the doctor. Although, it provides significant benefits but has some side effects as well such as constipation, dizziness, back pain, diarrhea, insomnia, joint pain, low blood platelets, and so on.