Staying hydrated is the priority. Sip water, diluted squash, or oral rehydration salts regularly; these replace lost salts and sugars better than water alone, especially for children and older adults. Avoid relying on very sugary fizzy drinks, which can worsen diarrhoea.
Once you feel like eating, choose small, plain meals such as toast, rice, bananas, potatoes, plain crackers or soup. There is no need to stick rigidly to one diet; eat what you can tolerate and return to normal foods gradually. Limit greasy, very sweet, spicy foods, alcohol and caffeine for a few days.
Wash hands well and avoid preparing food for others while symptomatic to prevent spreading infection. Seek medical advice if you cannot keep fluids down, show signs of dehydration, or symptoms are severe or prolonged. Contact a doctor promptly for unwell infants, frail older people, or anyone with a weakened immune system.