Nausea - Causes and Symptoms

Definition

Nausea is a disorder characterized by an unpleasant feeling of malaise accompanied by the desire to vomit. This symptom is often associated with disgust with food or certain odors, discomfort in the stomach and autonomic changes, such as increased heart rate and abundant production of saliva. Other concomitant manifestations include pallor, dizziness and sweating. Nausea and vomiting typically occur in sequence; however, these symptoms may also occur separately (vomiting is not always preceded by nausea).

The causes that can trigger an attack of nausea are numerous and can originate in the gastro-intestinal tract or in the central nervous system. In particular, the emetic center can be activated by neural pathways afferent from the digestive organs (including pharynx, stomach and small intestine) and not (eg heart and testicles) and in other centers of the CNS (eg brainstem and vestibular system) .

Gastrointestinal disorders that cause this symptom include gastroenteritis, gastroesophageal reflux disease, hepatitis, gastroparesis and intestinal obstruction. Even eating quickly, swallowing air and excessively abundant meals can be causes of occasional nausea.

As for the central nervous system, on the other hand, nausea can result from closed head injury, cerebral haemorrhage, labyrinthitis, headache and motion sickness.

Other causes to consider include injuries to the inner ear, serious infections (such as meningitis and pyelonephritis), acute abdomen (eg appendicitis, cholecystitis, pancreatitis and perforation of a bowel) and increased intracranial pressure secondary to an occupying lesion space (eg trauma or brain tumor). The nausea can also depend on emotional factors, psychological disorders, particular stimuli (olfactory, visual and gustatory and very intense pain), state of pregnancy and intake of some drugs (chemotherapy, anesthetics, oral contraceptives and antibiotics).

Nausea can also derive from various systemic diseases, such as advanced neoplasms, diabetic ketoacidosis and liver or kidney failure. Less frequent causes include sepsis, food intolerances, metabolic disorders, exposure to radiation and ingestion of toxic substances (eg iron or ethanol).