Food poisoning, also called foodborne illness, is illness caused by eating contaminated food. Infectious organisms — including bacteria, viruses and parasites — or their toxins are the most common causes of food poisoning. Infectious organisms or their toxins can contaminate food at any point of processing or production. Contamination can also occur at home if food is incorrectly handled or cooked. 

Food poisoning symptoms, which can start within hours of eating contaminated food, often include nausea, vomiting or diarrhea. Most often, food poisoning is mild and resolves without treatment. But some people need to go to the hospital. 

Symptoms

Food poisoning symptoms vary with the source of contamination. Most types of food poisoning cause one or more of the following signs and symptoms:

• Nausea
• Vomiting
• Watery or bloody diarrhea
• Abdominal pain and cramps
• Fever

Signs and symptoms may start within hours after eating the contaminated food, or they may begin days or even weeks later. Sickness caused by food poisoning generally lasts from a few hours to several days.

When to see a doctor

If you experience any of the following signs or symptoms, seek medical attention.

• Frequent episodes of vomiting and inability to keep liquids down
• Bloody vomit or stools
• Diarrhea for more than three days
• Extreme pain or severe abdominal cramping
• An oral temperature higher than 100.4 F (38 C)
• Signs or symptoms of dehydration — excessive thirst, dry mouth, little or no urination, severe weakness, dizziness, or lightheadedness
• Neurological symptoms such as blurry vision, muscle weakness and tingling in the arms

Food Poisoning

Most of us are all too familiar with the unpleasant symptoms of food poisoning, from vomiting to diarrhoea and debilitating stomach cramps. Although viruses play a role, bacteria are common offenders, with Salmonella and Campylobacter topping the poisoning charts. Some bacteria wreak havoc by multiplying in the body before delivering their toxins, which spark an immune reaction in the gut. Others, such as Staphylococcus aureus, poison us by contaminating food with toxins. 

Bacteria enter

Bacteria multiply

Immune response

Flooded intestines

Diarrhoea and dehydration

Vomiting