Food can become contaminated by bacteria e.g. salmonella or E. coli, viruses e.g. norovirus, or parasites e.g. giardia in many ways including:
- not cooking food thoroughly (especially meat) - use a food thermometer if concerned
- not keeping certain foods below 5°C
- leaving cooked food out in warm temperatures
- not sufficiently reheating cooked food
- someone who is ill or who has dirty hands touching the food
- eating food after its "use by" date
After eating contaminated food you may get any of:
- stomach cramps
- loss of appetite
It will usually pass in a day or so but in the meantime make sure you drink lots of fluids, preferably with electrolyte powders e.g. dioralyte; and bland food such as toast and biscuits that are easy to digest, when you can face it.
Call 111 for medical advice if you are worried or can't keep any fluids down.