Food poisoning is an illness that can cause nausea, vomiting, or diarrhea. It is caused by eating food that contains germs, such as bacteria, viruses, or parasites.
Most people recover at home within a few days. The main risk is dehydration, so replacing fluids matters more than anything else.
What causes food poisoning?
Food poisoning happens when you eat or drink something contaminated with germs. Two examples of bacteria that are common causes of food poisoning are Salmonella and E. coli. Viruses such as norovirus are also frequent causes, especially in group settings.
Parasites, including tiny worms that people can catch in some countries, can cause it too.
How soon do symptoms start?
| Cause | Typical onset |
|---|---|
| Staph toxin | 1 to 6 hours |
| Norovirus | 12 to 48 hours |
| Salmonella | 6 hours to 6 days |
| E. coli | 1 to 8 days |
Because the timing varies so much, a food diary can help your doctor narrow down the cause.
What are the symptoms of food poisoning?
- Nausea and vomiting
- Watery or bloody diarrhea
- Stomach cramps
- Fever and chills
- Feeling weak or dizzy from fluid loss
How is food poisoning treated?
Most cases need rest and fluids. Drink small sips of water, an oral rehydration solution, or clear broth often. Avoid dairy, caffeine, and very fatty foods until you feel better.
Do not take anti-diarrheal medicine without asking a doctor, especially if you have a fever or bloody stools, because it can slow your body’s ability to clear the infection.
When should you see a doctor for food poisoning?
See a doctor if you cannot keep fluids down, if you have blood in your stools, if you have a fever above 101 degrees Fahrenheit, or if symptoms last more than three days.
Young children, older adults, and anyone with a weakened immune system should be seen sooner.
Can food poisoning be prevented?
Yes. Washing your hands, cooking meat until it is well done, and keeping cold food cold prevent most cases. Our related article on preventing food poisoning covers those steps in detail.
Should you use anti-diarrheal medicine for food poisoning?
Ask a doctor first, especially if you have a fever or bloody stools. Anti-diarrheal medicine can slow your body’s ability to push the germs out, which may make the illness last longer.
For simple watery diarrhea without a fever, some people use it for comfort. Check with a doctor or pharmacist before you do.
How can you avoid spreading food poisoning at home?
Some causes, such as norovirus and Salmonella, pass easily from person to person. Wash your hands with soap after using the bathroom, after changing diapers, and before you touch food.
Do not prepare meals for others while you are sick, and clean the bathroom and kitchen surfaces you share. Wash the towels and linens you use in hot water.
How can you avoid getting food poisoning again?
Prevention comes down to four habits: clean, separate, cook, and chill. Keep raw meat away from ready-to-eat food, wash your hands and boards often, and chill leftovers quickly.
A food thermometer takes the guesswork out of cooking meat until it is well done. Our article on preventing food poisoning walks through those steps in more detail.
How do you know if food poisoning is serious?
Most cases pass on their own, so the warning signs matter more than the label. Get medical help if you cannot keep any fluids down, if you have blood in your stools or vomit, or if you feel confused or very weak.
Signs of dehydration include a dry mouth, little or no urine, and dizziness when you stand up. Those are reasons to be seen the same day rather than to wait it out.
Who is at higher risk from food poisoning?
Young children, adults over 65, pregnant women, and anyone with a weakened immune system can get sicker faster and need care sooner. For these groups, dehydration can set in before symptoms look severe.
If you fall into one of these groups and you cannot keep fluids down, do not wait for symptoms to pass on their own.
What should you drink when you have food poisoning?
Fluids are the main treatment. Take small sips often instead of large amounts at once, because a full stomach can trigger more vomiting.
- Water, sipped slowly and often.
- An oral rehydration solution, which replaces salts as well as water.
- Clear broth, which adds fluid and some salt.
- Plain, caffeine-free drinks in small amounts if broth does not appeal to you.
Skip dairy, caffeine, alcohol, and very fatty foods until your stomach settles. If you cannot keep even small sips down, call your doctor.
Which foods cause food poisoning most often?
Any food can carry germs, but some carry them more often. Raw or undercooked poultry and meat, raw eggs, unpasteurized milk and juice, and unwashed produce are the usual suspects. Raw sprouts and pre-cut fruit are also risky when they sit at room temperature.
Food left out too long is the other common cause. Perishable food left at room temperature for more than two hours, or one hour in hot weather, should be thrown away rather than tasted.
What should you do if you think food poisoning came from a restaurant?
Write down what you ate and when, because timing helps your doctor narrow down the cause. A short food diary is more useful than a guess.
Report the illness to your local health department if several people who ate together got sick. If your symptoms are severe, our urgent care team can check you the same day, and our guide on whether food poisoning can be prevented covers the steps that keep germs out of your kitchen. When symptoms do not follow the usual pattern, in-house lab testing can help identify the cause.
Can you exercise while you are recovering?
Wait until you feel steady and can keep fluids and food down without trouble. Rest is part of recovery, because your body is using energy to clear the infection and to replace what you lost.
Start with gentle walking once your appetite returns, and build back up slowly. Stop and rest if you feel dizzy or unusually tired.
Should you take electrolytes?
An oral rehydration solution is the best choice when you have diarrhea and vomiting together, because it replaces salts along with water. Sports drinks usually carry more sugar and fewer salts, so they are a weaker option.
Plain water works well for mild cases, especially if you are also eating. Ask your doctor if you take medicine for a heart or kidney condition, because those affect how much fluid you need.
What if your symptoms keep coming back?
Symptoms that improve and then return deserve a medical look. A doctor can check for dehydration, review what you ate, and decide whether any testing is needed.
Frequently asked questions
How long does food poisoning last?
Most cases improve within 24 to 72 hours. Some bacterial infections, such as E. coli, can take a week or longer.
What should I eat after food poisoning?
Start with bland foods such as crackers, rice, bananas, and toast. Add other foods gradually as your stomach settles.
When is food poisoning an emergency?
Seek emergency care for severe dehydration, blood in vomit or stool, confusion, or a fever above 102 degrees Fahrenheit.
Can food poisoning spread to other people?
Some causes, such as norovirus and Salmonella, can spread from person to person. Wash your hands carefully and do not prepare food for others while you are sick.
