Nausea

Nausea is a broad feeling of unease and physical discomfort, often accompanied by a sense that vomiting might occur. When it lasts for a long time, it can become severely disabling, with people reporting a queasy sensation in the chest, stomach, or the back of the throat. A 2011 book on the subject cataloged more than 30 different ways to define this symptom.

Because nausea is a non-specific symptom, it can stem from a wide range of causes. The most frequent triggers include gastrointestinal infections and food poisoning, along with motion sickness, dizziness, migraines, fainting, low blood sugar, anxiety, overheating, dehydration, and lack of sleep. Many medications, such as those used in chemotherapy, list nausea as a side effect. It is also common in early pregnancy, where it is called morning sickness, and can be brought on by feelings of disgust or depression.

Medications designed to prevent or treat nausea and vomiting are known as antiemetics. In the United States, the most commonly prescribed options are promethazine, metoclopramide, and the newer drug ondansetron. The word "nausea" traces back through Latin to the Greek "nausia" or "nautia," meaning seasickness, and ultimately to the Greek word for ship.

**Causes**

Gastrointestinal infections account for 37% of acute nausea and vomiting cases, with food poisoning being the second most common cause. Side effects from medications (3%) and pregnancy are also frequent triggers. Chronic nausea has many possible origins, and in about 10% of cases, no specific cause is ever found. Aside from morning sickness, men and women report nausea at similar rates. After childhood, the frequency of doctor visits for nausea steadily declines with age, and among people over 65, less than one percent of medical consultations are for this symptom.

**Gastrointestinal**

Acute nausea and vomiting most often result from a gastrointestinal infection. Chronic nausea can be a primary symptom of various digestive disorders, including gastroesophageal reflux disease, functional dyspepsia, gastritis, biliary reflux, gastroparesis, peptic ulcer, celiac disease, non-celiac gluten sensitivity, Crohn's disease, hepatitis, upper gastrointestinal malignancy, and pancreatic cancer. An uncomplicated *Helicobacter pylori* infection does not typically cause chronic nausea.