Nausea (Latin nausea, from Greek ναυσία - nausia, “ναυτία” - nautia, motion sickness“, “feeling sick or queasy”) is a sensation of unease and discomfort in the upper stomach with an involuntary urge to vomit.
It occasionally precedes vomiting. A person can suffer nausea without vomiting. (Greek ναῦς - naus, “ship”; ναυσία started as meaning “seasickness”.) When prolonged, it is a debilitating symptom.
Nausea is a non-specific symptom, which means that it has many possible causes. Some common cause of nausea are motion sickness, dizziness, migraine, fainting, gastroenteritis (stomach infection) or food poisoning. Nausea is a side effect of many medications including chemotherapy, nauseants or morning sickness in early pregnancy. Nausea may also be caused by anxiety, disgust and depression.
Medications taken to prevent and treat nausea are called antiemetics. The most commonly prescribed antiemetics in the US are promethazine, metoclopramide and ondansetron.
see Postoperative nausea.