Vomiting is the forceful upheaval of the contents of the stomach. Vomiting usually occurs in cases of food poisoning, influenza, early pregnancy, motion sickness, or when someone is inebriated. Vomiting may also be a reaction to anesthesia, caused by the fact that the chemicals used to induce or maintain anesthesia are perceived as toxins by the body's defenses and trigger the same reflexes as if they had been ingested.
Self-induced vomiting, as a means of avoiding weight gain after binge eating, is known as bulimia nervosa. It is closely linked to the psychological disorder anorexia nervosa.