Vomiting
Vomiting occurs when, under the influence of the vagus nerve, the sphincter between the stomach and the oesophagus opens and the muscles of the stomach contract vigorously, causing a forceful ejection of the stomach contents. This can be the result of direct irritation of the gastric mucosa by a toxic substance or an infectious agent, as happens in food poisoning or gastroenteritis, or it may be the result of disorders situated well away from the stomach, such as migraine or motion sickness. The reflex is co-ordinated by a part of the brain called the chemoreceptor trigger zone. There are certain drugs which stimulate this area directly - particularly some of those used in the treatment of Cancer, when the reflex can be suppressed using anti sickness agents, but if the cause is direct irritation of the stomach by a noxious substance, then the best treatment is fluid replacement while the body works to rid itself of whatever is irritating it.
Infants and young children are especially prone to vomiting, often in association with a viral infection causing an elevated temperature and diarrhoea. The main risk for these children is dehydration: oral rehydration preparations should be proffered often (they usually don’t bring back all that goes in - though it often seems so) and temperature reduced - paracetamol given by suppository to the feverish vomiting infant is effective. Persistent symptoms in a small child need medical attention.
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