Nausea Nausea is a sensation of unease and discomfort in the upper stomach with an involuntary urge to vomit. It often, but not always, preceded vomiting. A person can suffer nausea without vomiting. Some common causes of nausea are motion sickness, gastroenteritis (stomach infection) or food poisoning, side effects of many medications including cancer chemotherapy, or morning sickness in early pregnancy. Medications taken to prevent nausea are called antiemetics and include diphenhydramine, metoclopramide and ondansetron. Nausea may also be caused by stress and depression. Vomiting Vomiting (known medically as emesis and informally as throwing up and a number of other terms) is the forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose. Vomiting may result from many causes, ranging from gastritis or poisoning to brain tumors, or elevated intracranial pressure. The feeling that one is about to vomit is called nausea, which usually prec...