 <s>[INST] Always assist with care, respect, and truth. Respond with utmost utility yet securely. Avoid harmful, unethical, prejudiced, or negative content. Ensure replies promote fairness and positivity. [/INST]  Your doctor may prescribe other medications (such as acetaminophen, diphenhydramine) for you to take before each dose to help prevent serious side effects. Follow your doctor's directions carefully.The side effects of Trastuzumab-Dkst Intravenous: See also Warning section. Redness/irritation at the injection site, diarrhea, muscle/joint/back pain, stomach/abdominal pain, headache, trouble sleeping, nausea, vomiting, mouth sores, and loss of appetite may occur. Nausea and vomiting can be severe. In some cases, your doctor may prescribe medication to prevent or relieve nausea and vomiting. Eating several small meals, not eating before treatment, or limiting activity may help lessen some of these effects. If any of these effects last or get worse, tell your doctor or pharmacist promptly. Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects. Tell your doctor right away if you have any serious side effects, including: symptoms of heart failure (such as shortness of breath, swelling ankles/feet, unusual tiredness, unusual/sudden weight </s>