Sickness and diarrhoea bugs are caught easily and are often passed on in places where there are lots of children - like playgroups or nurseries.
Feeling sick and suddenly being sick are normally the first signs. Diarrhoea can follow afterwards. Diarrhoea can cause dehydration so increase fluid intake.
Take them to see your GP if they are unwell and have had three or more vomits or six or more poos in 24 hours or sooner if they are newborn or if you notice signs of dehydration.
If you are breastfeeding, keep on doing so. Older children should have plenty of fluids to drink - little and often is best - every 10 minutes. You can also offer them an ice-lolly for them to suck. If they want to eat, give them plain foods like pasta or boiled rice (nothing too rich or salty).
Keep them away from others, especially children, to reduce the chance of passing the infection on. Regularly wash hands with warm water and soap to reduce the chance of passing the infection on. If you are out use handgel.