Food poisoning symptoms, causes and how long recovery takes

You had a takeaway on Friday. By Saturday evening you were on the bathroom floor, and the person who ate exactly the same thing is completely fine. It feels like a puzzle, and it is one reason food poisoning gets blamed on the wrong meal so often.

Food poisoning is an infection or a toxin you swallowed along with something you ate or drank. That is the whole of it. What muddles people is the gap between the meal and the symptoms, which can be two hours or, for a few organisms, several weeks.

Where it actually comes from

Raw meat, chicken above all, is the usual starting point in a British kitchen. The bacteria live in the animal's gut and end up on the surface of the meat and in the packaging liquid. Cooking kills them. Charring the outside while the middle stays pink does not, and nor does putting cooked chicken back on the board you jointed it on.

• Undercooked poultry and minced meat. A steak can be rare because the inside was never exposed. Mince is different, since grinding spreads surface bacteria all the way through, which is why burgers need cooking properly.
• Rice and pasta left standing. A spore-forming bacterium survives cooking and multiplies while the food sits at room temperature. Reheating later kills the bacteria but not the toxin they have already produced.
• Cooked food handled and then left warm. Sliced meats, cream cakes, sandwich fillings, buffet trays: neither properly hot nor properly cold.
• Unpasteurised milk and cheese, pate and cold smoked fish, a particular risk in pregnancy and for anyone immunosuppressed.
• Salads, ice and tap water abroad, plus unpeeled fruit rinsed in water you would not drink.

How long after the meal symptoms start

This is the part that solves the puzzle. Different organisms have different incubation periods, so the timing points towards a likely cause and frequently rules out the meal you are busy blaming.

• Within about one to six hours. Sudden forceful vomiting with cramps and not much diarrhoea. The toxin was already in the food, and reheated rice or a dish that sat out at a party are the classic sources.
• Around eight to sixteen hours. Cramping and watery diarrhoea with less vomiting, typical of stews and gravies cooked in bulk then cooled too slowly.
• Twelve hours to three days. Fever, cramps and diarrhoea from salmonella, often traced to poultry, eggs or unpasteurised dairy.
• Two to five days. Campylobacter, the commonest cause of bacterial food poisoning here, usually from chicken. It often opens with a day of aching and fever before any diarrhoea, which is why people assume they have flu.
• Three or four days, sometimes with blood. Certain strains of E. coli, from undercooked mince, unpasteurised milk or farm animals. Bloody diarrhoea always needs assessing.
• Weeks. Listeria can take a fortnight or longer, which is why the link to one food is so hard to establish.

The last thing you ate is rarely the thing that made you ill. If symptoms began today, the suspect meal usually sits between yesterday and last week, so try to recall the whole week rather than just dinner.

What it feels like

The pattern varies with the organism, but most people get some combination of nausea, vomiting, cramps that arrive in waves, diarrhoea, aching and a temperature. Appetite vanishes entirely. Toxin-driven illness tends to be violent and short, while infection of the gut lining builds more slowly, lasts longer and brings more fever. Neither pattern is reliable enough to diagnose yourself with, but both are worth describing accurately when you are assessed for food poisoning, along with who else ate the same meal.

How long recovery takes

Most food poisoning settles within a few days and needs no specific treatment. Vomiting usually stops first, often inside a day. Diarrhoea takes longer, and your bowel habit can stay unpredictable for a week or two after you feel well. Tiredness lingers too, and if it drags on well beyond a fortnight then tiredness that will not lift is worth looking at in its own right.

Fluids are the treatment that actually matters, far more than anything you can buy. Rehydration and what to eat are covered in our practical guide to managing diarrhoea and vomiting. If the illness is working its way through your household rather than affecting only the people at one meal, you are probably dealing with a stomach bug rather than contaminated food, and stopping the spread becomes the priority.

When to get urgent help

Food poisoning is usually unpleasant rather than dangerous. These are the exceptions:

• Blood in your stool, or stools that look black and tarry
• Being unable to keep any fluid down for a whole day
• Signs of dehydration: dark urine or hardly any, a dry mouth, feeling faint as you stand
• Severe or constant abdominal pain, as opposed to cramps that ease between waves
• Symptoms that started during or soon after travel abroad
• A high fever, or shivering attacks you cannot control
• Illness in someone pregnant, elderly, frail or immunosuppressed

Call 999 for severe abdominal pain, vomiting blood, or anyone drowsy and hard to wake. Use 111 for urgent advice that falls short of an emergency, such as a full day without keeping fluids down, or symptoms that began after a trip abroad. Feeling dizzy every time you stand after two days of fluid loss is a signal to act.

How an online consultation works for this

Most people with food poisoning never need a doctor. The ones who do usually have a specific question: is this normal, is it lasting too long, did I pick something up abroad, and is it safe to keep waiting this out.

A video appointment answers that. You give the timeline, the meals beforehand, what the stool looks like and how much you are drinking, and a UK registered doctor tells you where you stand. They may prescribe where it is clinically appropriate, although for most food poisoning antibiotics do not help and can prolong matters. If you need examining in person, they will say so and can write a referral letter. Have a look at how an online appointment runs and what it costs in pounds, or arrange an appointment straight away.

Not going through that again

Most of food safety is dull and effective. A handful of habits prevent most home kitchen cases.

• Do not wash raw chicken. It sprays bacteria round your sink and worktop, and cooking would have dealt with them anyway.
• Keep separate boards and knives for raw meat, or handle it last and wash everything in hot soapy water afterwards.
• Cook poultry, mince, burgers, sausages and kebabs until no pink meat remains and the juices run clear.
• Cool leftovers fast in shallow containers rather than leaving a deep pot on the hob overnight, then reheat once only until piping hot.
• Take use-by dates seriously. Best before is about quality, use by is about safety.
• Abroad, be wary of ice, salads rinsed in tap water, unpeeled fruit and buffet food standing in the heat. Bottled or boiled water, even for brushing your teeth, beats a ruined week.

Barbecues deserve their own warning, because the outside chars long before the middle is cooked and tongs travel from the raw platter back to finished food. Cook meat through indoors first if you can, then finish it on the grill.

If you are several days in without improving, or you are worried about how much fluid you are losing, get it looked at properly rather than waiting another night. Book a consultation now, describe the meal and the timeline, and let a UK registered doctor tell you whether this needs treating or simply needs time.