Forcible regurgitation of the contents of the stomach. Vomiting has various causes, which may lie in the abdomen, the stomach and intestine itself, the brain, or other disorders that stimulate the brain. Psychological causes should not be ruled out. Brain conditions can cause vomiting by stimulating the vomiting centres in the brain, and this can also occur as a result of pressure on the brain, brain tumours, migraine, meningitis and disorders of the organs of balance. Psychological causes are reaction to stress, a disgusting sight or smell, or conditions such as anorexia nervosa or bulimia. Associated factors and symptoms must be examined to establish the cause. Is the vomiting acute, chronic or occurring as separate attacks? The vomit itself can be examined: is it digested, does it contain blood? The relationship with the food eaten is also important. Are there associated symptoms such as diarrhoea, fatigue, loss of appetite, fever, abdominal pain, abdominal swelling, and so on. Acute vomiting is usually caused by drinking too much alcohol or by an infection of the alimentary tract (gastroenteritis), or by a virus or bacterium. Vomiting is then usually associated with diarrhoea and a general feeling of malaise, making the cause clear. Less common causes of acute vomiting can be inflammation of the liver (associated with very poor appetite and yellow skin), gallstones (associated with severe pain in the upper abdomen), kidney stones (associated with severe lumbar pain), appendicitis (with pain in the right-hand side of the lower abdomen) or a brain condition (whether or not associated with headache, but with no symptoms other than the vomiting). Chronic (persistent) vomiting can be associated with pyloric stenosis (with typical, so-called projectile vomiting), with a stomach ulcer (with violent pain in the upper abdomen), or with stomach cancer (with loss of weight). Conditions not associated with the alimentary tract with vomiting as a symptom are liver or kidney failure, treatment with certain medicines, but also pregnancy, especially in the early months (morning sickness or hyperemesis gravidarum). Treatment is by treatment of the cause; one of the most common, gastroenteritis, can be treated without recourse to a doctor by a suitable diet of tea or broth, but if small children suffer simultaneously from severe vomiting and diarrhoea a doctor should be consulted, because they are more prone to dehydration.