Why food poisoning normally occurs

Contamination can happen when food is undercooked, stored at an unsafe temperature, handled with unwashed hands, or exposed to dirty equipment or water. Germs can also spread from one food to another, such as from raw ingredients to ready-to-eat meals. Some organisms multiply in food, while others leave toxins that irritate the gut. Symptoms may include diarrhoea, abdominal pain, nausea, vomiting and fever. The timing varies with the cause, so symptoms may start soon after eating or later. A shared meal followed by similar illness in several people can be a useful clue, but it does not prove which food was responsible.

Replace lost fluid with regular sips of water or oral rehydration solution. Eat when able, choosing small meals that are easy to tolerate, and rest. Do not prepare food for others while you have diarrhoea. Wash hands carefully after using the toilet and before eating; clean shared bathroom surfaces. Keep notes about when symptoms began, what you ate, and whether anyone else became ill. This information can help a clinician decide whether testing or specific treatment is appropriate. Avoid taking leftover antibiotics, because treatment depends on the cause and some illnesses can worsen with unsuitable medicines.

Get urgent help for blood in the stool, severe abdominal pain, confusion, fainting, very little urine, or inability to drink enough. A fever with severe weakness also warrants prompt assessment. Seek medical advice earlier for a baby, an older adult, pregnancy, or a weakened immune system. If diarrhoea or vomiting continues, arrange a review so dehydration and other causes can be assessed.

Could a contaminated meal explain my symptoms, and should I have testing? How can I judge whether my fluid intake is enough? When can I safely return to work or cook for others?