What are foodborne illnesses most often caused by?

Contamination may happen when food is undercooked, kept at an unsafe temperature, handled with unwashed hands, or exposed to unsafe water. Some germs multiply in food; others cause illness after they enter the digestive tract. Certain bacteria can also leave toxins behind, so reheating may not remove every hazard.

Symptoms can include diarrhoea, nausea, vomiting, abdominal pain, or fever. The timing varies with the organism or toxin, so symptoms may begin soon after a meal or later. A single meal is not always the source; exposure can occur earlier.

Sip fluids often, using an oral rehydration solution if diarrhoea or vomiting is draining fluid and salts. Rest and eat small, plain meals when you feel able. Wash your hands carefully and avoid preparing food for other people while unwell. Do not take antibiotics unless a clinician recommends them, because treatment depends on the cause.

Seek urgent medical advice for confusion, fainting, severe weakness, trouble keeping fluids down, blood in stool or vomit, severe abdominal pain, or signs of dehydration such as very little urine. Contact a clinician sooner for an infant, older adult, pregnancy, or a person with a condition that affects immunity. If several people became ill after sharing food, report the suspected exposure to a healthcare professional.

Ask which symptoms require testing, how to replace fluids, whether any medicines are appropriate, and how long to avoid preparing food for others. Tell the clinician what you ate, when symptoms began, and whether anyone else who shared the meal is ill.