Nausea and vomiting in adults and children has a range of causes. Vomiting is usually a symptom of an underlying problem and the cause of prolonged vomiting needs to be investigated and determined to ensure the most effective treatment.

Some of the causes of vomiting include:

1. Problems in the digestive or gastrointestinal tract
   • Gastroenteritis or food poisoning
   • Excessive eating
   • Obstruction in the outlet of the stomach, a condition called pyloric stenosis. This may be seen in babies and leads to a projectile or fountain-like expulsion of vomit
   • Intestinal obstruction
   • Peptic ulcer
   • Gastroesophageal reflux disease
   • Gastritis
   • Peritonitis or inflammation of the membranes within the abdomen
   • Paralytic ileus or paralysis of the normal propulsive movements of the gut, usually after abdominal surgery
   • Allergic reactions for example milk allergy or lactose intolerance
   • Appendicitis
   • Pancreatitis
   • Cholecystitis or gall bladder inflammation and gall bladder stones
   • Liver disease or hepatitis
2. Inner ear and the nervous system
   • Motion sickness
   • Ménière's disease
   • Vertigo
3. Brain and the central nervous system
   • Migraine
   • Head injuries and concussion
   • Stroke and bleeding within the brain
   • Brain tumours or brain cancer
   • Raised intracranial pressure or pressure within the brain
   • Collection of fluid in the skull or hydrocephalus
4. Alteration of metabolites and electrolytes
   • Raised calcium in blood
   • Raised or lowered blood sugar
   • Raised potassium in blood
   • Accumulation of urea and urinary metabolites in blood or uremia
   • Insufficient adrenal gland hormones
5. Morning sickness associated with pregnancy
6. Viral infections such as swine flu, norovirus infection, Norwalk virus and chicken pox.
7. Medications such as chemotherapeutics, opioids and antidepressants. Anesthesia may also lead to intense nausea and vomiting after surgery. Exposure to radiation therapy also causes vomiting.
8. Drugs of abuse such as alcohol and opioids
9. Eating disorders such as bulimia nervosa and anorexia nervosa
10. Anxiety disorders and depression
11. Poisoning
12. Disagreeable sights, smells or thoughts
13. Fear, anxiety or violent emotions
14. Severe pain
15. Headaches
16. Heart attack
17. Excessive exercise especially on a full stomach