
Do not 'starve' a child with gastroenteritis. This used to be advised but is now known to be wrong.
You should not give drugs to stop diarrhoea to children under 12 years old. They sound attractive remedies, but are unsafe to give to children due to possible serious complications. However, you can give paracetamol or ibuprofen to ease a high temperature or headache.
If symptoms are severe, or persist, a doctor may ask for a sample of the diarrhoea. This is sent to the lab to look for infecting germs (bacteria, parasites, etc). Sometimes an antibiotic or other treatments are needed, depending on the cause of the infection.
Some research studies suggest that taking probiotics may reduce the duration of diarrhoea by about one day. Probiotics are dietary supplements of 'good, non-harmful' bacteria or yeasts. The theory is that these 'good' bacteria and yeasts multiply in the gut and protect the gut from the 'bad' infecting bacteria or virus. Probiotics are not available on NHS prescription. If you wish to try them you can buy them at supermarkets and other stores. Probiotics are sold as capsules, yoghurt products, etc. There is no evidence to prefer any particular form, strength, or dose.