Food poisoning is an illness caused by eating contaminated food. It's not usually serious and most people get better within a few days without treatment.

In most cases of food poisoning, the food is contaminated by bacteria, such as salmonella or Escherichia coli (E. coli), or a virus, such as the norovirus.

Signs and symptoms

The symptoms of food poisoning usually begin within one to two days of eating contaminated food, although they may start at any point between a few hours and several weeks later.

The main symptoms include:

• feeling sick (nausea)
• vomiting
• diarrhoea, which may contain blood or mucus
• stomach cramps and abdominal (tummy) pain
• a lack of energy and weakness
• loss of appetite
• a high temperature (fever)
• aching muscles
• chills

In most cases, these symptoms will pass in a few days and you will make a full recovery.

What to do

Most people with food poisoning recover at home and don't need any specific treatment, although there are some situations where you should see your GP for advice (see below).

Until you feel better, you should rest and drink fluids to prevent dehydration. Try to drink plenty of water, even if you can only sip it.

Eat when you feel up to it, but try small, light meals at first and stick to bland foods – such as toast, crackers, bananas and rice – until you begin to feel better.

Oral rehydration solutions (ORS), which are available from pharmacies, are recommended for more vulnerable people, such as the elderly and those with another health condition.

Read more about treating food poisoning.

When to see your GP

You should contact your GP if:

• your symptoms are severe – for example, if you're unable to keep down any fluids because you are vomiting repeatedly
• your symptoms don't start to improve after a few days
• you have symptoms of severe dehydration, such as confusion, a rapid heartbeat, sunken eyes and passing little or no urine
• you're pregnant
• you're over 60
• your baby or young child has suspected food poisoning
• you have a long-term underlying condition, such as inflammatory bowel disease (IBD), heart valve disease, diabetes or kidney disease
• you have a weak immune system – for example, because of medication, cancer treatment or HIV

In these situations, your GP may send off a stool sample for analysis and prescribe antibiotics, or they may refer you to hospital so you can be looked after more closely.

How is food contaminated?

Food can become contaminated at any stage during production, processing or cooking. For example, it can be contaminated by:

• not cooking food thoroughly (particularly meat)
• not correctly storing food that needs to be chilled at below 5C
• leaving cooked food for too long at warm temperatures
• not sufficiently reheating previously cooked food
• someone who is ill or who has dirty hands touching the food
• eating food that has passed its "use by" date
• the spread of bacteria between contaminated foods (cross-contamination)

Foods particularly susceptible to contamination if not handled, stored or cooked properly include:

• raw meat and poultry
• raw eggs
• raw shellfish
• unpasteurised milk
• "ready-to-eat" foods, such as cooked sliced meats, pâté, soft cheeses and pre-packed sandwiches

Read more about the causes of food poisoning and preventing food poisoning.