Many chemotherapy drugs and radiation cause nausea (upset stomach), but there are medicines to prevent nausea and vomiting. Please talk to your doctor or nurse if you are having nausea. You can either take medicines by mouth or intravenously (through a vein) when you have chemotherapy. Unfortunately, some patients still have some nausea. If the medicines do not help you, please go to the nearest emergency room right away. You may need fluids if you have not been able to eat or drink.