Nausea (from Gr., a ship, from its presence in sea sickness), the sickening sensation at the pit of the stomach which usually precedes vomiting. Nausea may be produced by a variety of causes: by the introduction into the stomach of nauseating or emetic drugs, by continued rotation or swinging of the body, by the unaccustomed motion of a vessel upon the waves, by food which disagrees with the stomach either in quantity or quality, sometimes by a blow upon the head, and in sensitive persons by offensive odors, by sudden alternations of temperature, and even by disagreeable news or moral impressions. When followed by vomiting, it is usually relieved immediately upon the evacuation of the stomach. If not so relieved, and if long continued, it becomes excessively depressing, and may even be dangerous to life. If the sensation of nausea be excited by any substance which has been taken into the stomach, the best treatment is to favor the act of vomiting by copious draughts of warm water, and thus secure an early and complete evacuation of the stomach.

If it depends upon any other of the causes named, quiet, a horizontal position, and freedom from all sources of disturbance, are most effectual.