Complications from gastroenteritis occur mainly in young children or if you are 65 and , have chronic gastroenteritis or a weakened immune system. Possible complications of gastroenteritis include dehydration and malnutrition; irritable bowel syndrome(IBS) may occur later on. Contact your doctor if:you have severe pain or it doesn't respond to over-the-counter painkillers; the vomiting or diarrhoea continues for more than a few days or you can't drink or eat without being sick; there is blood or mucus in your diarrhoea; you have signs of dehydration, incl a very dry mouth, muscle cramps, reduced urine, sunken eyes and , later, confusion or irritability.
Attribution: BUPA