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 precedes, but does not always lead to, vomiting. Antiemetics are sometimes necessary to suppress nausea and vomiting, and, in severe cases where dehydration develops, intravenous fluid may need to be administered to replace fluid volume.