Food poisoning, the UK picture, the red flags - and when antibiotics belong.

A short illness caused by eating or drinking something contaminated with bacteria, viruses, parasites or preformed toxins. In the UK, Campylobacter, Salmonella and norovirus are the biggest causes - most cases settle in 24 to 72 hours with rest and fluids.

Timing and symptoms give clues. Very short onset (1 to 6 hours) with prominent vomiting points at a preformed bacterial toxin. Longer onset (over 12 hours) with fever and blood in the stool suggests invasive bacteria. Norovirus classically causes a shorter illness with more vomiting and less blood. Only stool testing confirms the pathogen.

Usually no. Most cases are self-limiting and antibiotics are reserved for specific pathogens - Campylobacter (azithromycin), Giardia (metronidazole), typhoid (ciprofloxacin or ceftriaxone) and a few others. In suspected STEC O157, antibiotics are actively avoided because they raise the risk of haemolytic uraemic syndrome.

Go urgently for signs of severe dehydration, bloody diarrhoea, high fever with confusion, descending paralysis, or if you are pregnant, immunocompromised or at the extremes of age. Prolonged vomiting that stops you keeping any fluid down is another reason to be seen.

Yes. Suspected food poisoning is a statutorily notifiable condition and clinicians report it to UKHSA before culture confirmation. Specific organisms - Salmonella, Shigella, Listeria, STEC, cholera, typhoid, botulism and others - are separately notifiable when identified in the laboratory.

The Food Standards Agency four rules cover most cases - cook food thoroughly (especially poultry, mince and eggs), chill leftovers within two hours, keep raw and cooked food separate, and clean hands, surfaces and utensils. In pregnancy, avoid unpasteurised dairy, soft cheeses, pâté, deli meats and undercooked meat.