Food poisoning
Food poisoning is the illness caused by food contaminated with germs or with the toxins they produce.
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Medicines commonly prescribed for Food poisoning
For informational purposes only. Always consult a doctor before using any medicine.
Dosage form: ORAL SOLUTION/SUSPENSION, 100 mg/mlActive substance: paracetamolManufacturer: Laboratorios Normon S.A.Prescription requiredDosage form: TABLET, 650 mgActive substance: paracetamolManufacturer: Laboratorio Stada S.L.Prescription not requiredDosage form: ORAL SOLUTION/SUSPENSION, 100 mg/mlActive substance: paracetamolManufacturer: Laboratorios Normon S.A.Prescription not required
Food poisoning is the illness caused by food contaminated with germs or with the toxins they produce. It usually settles by itself within a few days and can be managed at home. The danger comes less from the infection than from fluid loss: with vomiting and diarrhoea the body loses water and salts faster than it can replace them. The patient's main job is therefore to drink, and the family's main job is to notice in good time that home measures are no longer enough.
How it starts
The picture is much the same for everyone: nausea and vomiting, watery diarrhoea, cramping abdominal pain, weakness, shivering and often a temperature and a headache. There is no appetite, and that is normal.
The timing, though, depends on what got in, and it sometimes points to the culprit:
- from half an hour to a few hours — usually a toxin the bacteria had already made in the food itself: cream cakes, mayonnaise salads, boiled rice left out overnight;
- from one day to three — the commonest situation, with live bacteria from poultry, eggs or unpasteurised milk;
- more than a week — some organisms behave this way, so it is not only yesterday's supper that needs recalling.
Most of the time the whole thing is over within a few days. Diarrhoea may outlast the other complaints, and that alone is no sign that things are going badly.
Why food turns dangerous
Contamination happens in the most ordinary ways: the food was undercooked, kept somewhere warm, left standing on the table too long, prepared by someone who had not washed their hands, or raw meat touched ready-to-eat food by way of the same board or knife.
Most cases come down to campylobacter, salmonella and escherichia coli, plus norovirus, which reaches food from people. But a few variants deserve to be known separately, because they are more dangerous than usual and do not behave the way people expect.
- Botulism. Linked to home preserving, cured fish and smoked goods. It shows itself not through diarrhoea but through drooping eyelids, double vision, difficulty swallowing and speaking, and weakness spreading downwards. This is an emergency: call an ambulance even if the abdomen is entirely comfortable.
- Certain strains of escherichia coli that damage blood vessels. They cause bloody diarrhoea and, a few days later, can strike the kidneys and the blood, above all in children and older people. That is exactly why bloody diarrhoea must not be treated with medicines that stop the bowels, and why antibiotics must not be started without advice: both raise the risk.
- Listeria. It hides in soft cheeses made from unpasteurised milk, in pâté, smoked fish and prepared salads, and it can multiply even in the fridge. In a healthy adult it causes little more than mild illness, but in pregnancy it is dangerous for the baby, so those foods are best avoided during those months.
- Mushroom poisoning. The most treacherous kind is the one where the first hours pass uneventfully, symptoms arrive only towards the end of the day, and the damage falls on the liver. Here a late start signals the opposite of a mild course.
- A reaction to fish past its best. Tuna, mackerel and related species build up histamine when badly stored. Within half an hour to an hour come facial flushing, a hot feeling, headache and a rash — very much like an allergy, though it is not one.
Dehydration is the real danger
Dehydration is watched more closely than the temperature or the number of trips to the toilet.
In an adult it announces itself with a dry mouth and thirst, dark strong-smelling urine, passing water less often than usual, dizziness on standing, listlessness and sunken eyes.
In a small child the signs differ and are harder to spot: dry nappies or noticeably fewer wet nappies than usual, crying without tears, a sunken soft spot in a baby, drowsiness, an unfamiliar floppiness, refusing the breast or the bottle. In older people dehydration often shows up first as confusion.
A separate word about anyone taking water tablets or blood pressure medicines: with vomiting and diarrhoea these drugs worsen fluid loss, and the doctor may pause them for the duration of the illness.
What to do at home
Treatment amounts to rest and fluids; everything else is secondary.
- drink small amounts often: a few sips every few minutes stay down better than a glass at once;
- where losses are substantial use an oral rehydration solution from the pharmacy, which replaces the salts as well;
- carry on breastfeeding or bottle feeding, offering more frequent and shorter feeds; make up formula at the usual strength rather than watering it down;
- eat when you feel like it, starting with plain food and steering clear of fatty and spicy dishes; there is no need to fast deliberately;
- paracetamol may be taken for pain and fever, and children should have the children's preparation according to the packet;
- stay at home and allow yourself to rest.
What is best avoided:
- no fruit juice or fizzy drinks: sugary liquids pull water into the bowel and make diarrhoea worse;
- no medicines that stop diarrhoea if there is blood in the stool or a high temperature, and none at all for children;
- no starting antibiotics on your own initiative — in most food poisoning they achieve nothing and can do harm;
- no aspirin for children or teenagers;
- no cooking for other people and no going in to work if it involves food, caring for patients or looking after young children, normally until two days after the last episode of vomiting or diarrhoea;
- leave alcohol and coffee until you have recovered.
When to get help rather than wait
Call an ambulance straight away — in Spain, Italy, Portugal, Poland and Ukraine that is the single European number 112 — if any of these appear:
- vomiting blood or vomit that looks like coffee grounds;
- blood in the stool, or black stools;
- sudden severe abdominal pain, or an abdomen that is rigid and tender to touch;
- a sudden severe headache, a stiff neck, pain on looking at light;
- double vision, drooping eyelids, trouble swallowing or speaking;
- skin, lips or tongue turning blue, grey, pale or blotchy — on darker skin this shows more readily on the palms and soles;
- fast, laboured breathing;
- confusion, unusual drowsiness, or someone who cannot be roused;
- any suspicion of having swallowed something poisonous: mushrooms, an unknown plant, a spoilt home preserve.
See a doctor the same day if vomiting has prevented keeping down even a sip of water for more than a day, if signs of dehydration persist despite rehydration sachets, if diarrhoea lasts more than a week or vomiting more than two days, if you are worried about a baby under one, if a child has stopped taking the breast or the bottle, or if the illness began soon after returning from the tropics.
It is better not to drive yourself to hospital: weakness and dizziness make that dangerous. Take a list of your regular medicines with you.
Who is at greater risk
The same infection is not the same experience for everyone.
- babies and young children, in whom dehydration develops quickly;
- older people, particularly those living alone;
- pregnant women, because of listeria and the risk to the baby;
- people with weakened immunity: after chemotherapy, on immunosuppressive treatment, or without a spleen;
- people with diabetes, kidney disease, heart failure or inflammatory bowel disease;
- anyone on medicines that reduce stomach acid, since their barrier against bacteria is weaker.
These groups should contact a doctor earlier, without waiting until they feel truly awful.
How to avoid it
Almost all of it comes down to a handful of habits that work better than any remedy.
- wash hands with soap and water before cooking and after handling raw meat, fish and eggs; against norovirus alcohol gel is useless and soap is what counts;
- keep raw and cooked apart: separate boards, separate knives, raw meat on the bottom shelf of the fridge;
- do not wash raw chicken, since the splashes spread bacteria around the kitchen;
- cook poultry, mince, sausages and barbecued meat right through, until the juices run clear;
- put leftovers in the fridge within a couple of hours rather than leaving them to cool until bedtime;
- never leave cooked rice or pasta standing at room temperature: chill the leftovers quickly and reheat once until piping hot;
- defrost in the fridge rather than on the worktop, and do not refreeze what has thawed;
- go by the use-by date rather than the best-before date;
- when travelling, choose hot freshly cooked food, drink bottled or boiled water, and skip the ice and the unwashed fruit.
Online consultation
In an online consultation the doctor judges from your account how dehydrated you are and whether any sign calls for care in person, helps work out how much a child or an adult needs to drink, and explains which medicines are out of place right now. The doctor will also cover whether a stool test is worth doing, what to do about regular medication while the illness lasts, and when it is safe to return to work, school or nursery.
This material is for information only and does not replace medical advice.
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