ConditionDigestive system
Food Poisoning
Food poisoning is illness from eating food or drink contaminated with germs such as norovirus, Salmonella, Campylobacter or E. coli, or with toxins they produce. Symptoms usually include nausea, vomiting, diarrhea, stomach cramps and sometimes fever, starting anywhere from 30 minutes to several days after eating. Most people recover within 1 to 3 days with fluids and rest. Bloody diarrhea, high fever, signs of dehydration or symptoms in high-risk groups need medical care.
Also called: Foodborne illness, foodborne disease, food infection, stomach bug from food
At a glance
- What it is
- Illness from contaminated food or drink.
- Most common causes in the US
- Norovirus, Salmonella, Clostridium perfringens, Campylobacter, Staphylococcus aureus.
- Symptoms
- Nausea, vomiting, watery diarrhea, cramps, sometimes fever.
- Onset
- 30 minutes to several days after eating, depending on the germ.
- How long
- Usually 1 to 3 days. Some infections last a week or more.
- Treatment
- Fluids and oral rehydration. Antibiotics only for specific infections.
When to get help
Call 911 or go to the ER
- Blurred or double vision, drooping eyelids, slurred speech, difficulty swallowing or breathing, or weakness spreading down the body (possible botulism)
- Signs of severe dehydration: very little or no urine, dizziness on standing, confusion, a racing heart
- Vomiting blood, or black or heavily bloody stools
- Very little urine, pale skin and unusual tiredness a week or so after bloody diarrhea, especially in a child (possible hemolytic uremic syndrome)
- Food poisoning symptoms after eating wild mushrooms, or with numbness and tingling after eating fish or shellfish
See a doctor within a day or two
- Bloody diarrhea
- Fever above 38.9 °C (102 °F)
- Vomiting that prevents keeping liquids down for more than 12 hours, or diarrhea lasting more than 3 days
- Food poisoning in a pregnant person, a baby or young child, an adult over 65, or someone with a weak immune system
- Fever, muscle aches and stiff neck or confusion in a pregnant or older person after eating deli meats, soft cheeses or unpasteurized dairy (possible listeria)
Book a routine appointment
- Diarrhea or stomach upset that keeps returning after a bout of food poisoning
Usually safe to manage at home
- Vomiting and diarrhea in a healthy adult who can keep fluids down, with no blood, high fever or dehydration
What causes food poisoning
More than 250 different germs and toxins can cause foodborne illness. The CDC estimates that about 48 million Americans get sick from contaminated food each year.
| Germ | Common sources | Onset | Key features |
|---|---|---|---|
| Norovirus | Shellfish, salads, food handled by a sick person | 12 to 48 hours | Sudden vomiting and diarrhea, very contagious, 1 to 3 days |
| Staphylococcus aureus toxin | Foods handled then left warm: sandwiches, salads, pastries | 30 minutes to 8 hours | Sudden violent vomiting, no fever, under 24 hours |
| Bacillus cereus | Reheated rice and pasta | 30 minutes to 15 hours | Vomiting or diarrhea, short-lived |
| Clostridium perfringens | Large batches of meat, gravy kept warm | 6 to 24 hours | Diarrhea and cramps, rarely vomiting |
| Salmonella | Eggs, poultry, meat, sprouts, unpasteurized milk | 6 hours to 6 days | Fever, diarrhea, cramps, 4 to 7 days |
| Campylobacter | Undercooked chicken, unpasteurized milk | 2 to 5 days | Fever, cramps, sometimes bloody diarrhea |
| Shiga toxin-producing E. coli (O157) | Undercooked ground beef, leafy greens, raw milk | 3 to 4 days | Severe cramps, bloody diarrhea, risk of HUS |
| Listeria | Deli meats, soft cheese, smoked seafood, raw sprouts | Days to weeks | Fever and aches. Dangerous in pregnancy and older adults |
| Vibrio | Raw oysters | 24 hours | Watery diarrhea, dangerous in liver disease |
| Botulism | Improperly home-canned foods, fermented foods | 12 to 72 hours | Paralysis starting with eyes and face. Emergency |
Chemical and natural toxins also cause poisoning: scombroid (flushing and headache from spoiled tuna or mackerel), ciguatera (tingling and temperature reversal from reef fish), and toxic mushrooms.
Symptoms
- nausea and vomiting
- watery diarrhea, sometimes bloody
- stomach cramps and bloating
- fever and chills
- headache, muscle aches and weakness
Symptoms that start within a few hours of eating usually come from a preformed toxin. Those starting after a day or more are more often from germs multiplying in the gut.
Food poisoning vs stomach flu
Food poisoning and viral gastroenteritis ("stomach flu") overlap, and norovirus causes both. Clues to food poisoning include several people falling ill after the same meal, and onset within hours of a suspect food. Stomach flu spreads person to person and may run through a household over several days. Neither is related to influenza. See gastroenteritis.
How long does food poisoning last?
- Toxin-related (Staph, B. cereus): often under 24 hours
- Norovirus: 1 to 3 days
- Salmonella and Campylobacter: 2 to 7 days
- E. coli O157: 5 to 10 days
- Parasites such as Giardia or Cyclospora: weeks without treatment
Some people have lingering bowel sensitivity for weeks, and a minority develop post-infectious irritable bowel syndrome.
Who is at higher risk
- babies and young children
- adults over 65
- pregnant people, especially from listeria, which can cause miscarriage or stillbirth
- people with weakened immune systems from cancer treatment, transplants, HIV, steroids or diabetes
- people with liver disease (Vibrio)
Diagnosis
Most cases are diagnosed from symptoms and need no testing. A doctor may order stool tests if you have bloody diarrhea, high fever, severe illness, symptoms lasting more than a week, recent travel, or are in a high-risk group, or during a suspected outbreak. Blood tests check for dehydration and kidney problems. Report suspected outbreaks to your local health department.
Treatment
Fluids first
- sip water or oral rehydration solution (ORS) little and often, starting as soon as you can keep it down
- for children, use ORS rather than juice or sports drinks
- broth and weak tea are fine
- avoid alcohol, caffeine and very sugary drinks
Eating
Return to normal food as soon as you feel like it. Bland, easy foods such as toast, crackers, rice, bananas, soup, eggs and yogurt are good choices at first. There is no need to stick to a strict "BRAT" diet for long.
Medicines
- Loperamide can reduce watery diarrhea in adults, but avoid it with bloody diarrhea or fever. Follow the label.
- Bismuth subsalicylate may help diarrhea and nausea. It turns stool black. Do not give it to children or teenagers, because it contains a salicylate related to aspirin.
- Anti-nausea medicine may be prescribed when vomiting prevents drinking.
- Antibiotics are not needed for most cases and are avoided in suspected E. coli O157. They are used for severe Campylobacter or Salmonella in high-risk people, Shigella, listeria and some travel-related infections.
Botulism and severe cases
Botulism needs antitoxin and hospital care. Severe dehydration needs IV fluids.
Complications
- dehydration, the most common
- hemolytic uremic syndrome after E. coli O157
- reactive arthritis and, after Campylobacter, Guillain-Barré syndrome (rare)
- post-infectious IBS
- miscarriage or newborn infection from listeria
Prevention
Follow the four steps of food safety:
- Clean: wash hands for 20 seconds, and wash surfaces and utensils.
- Separate: keep raw meat, poultry, seafood and eggs away from ready-to-eat foods.
- Cook: use a food thermometer. Cook poultry to 165 °F (74 °C), ground meat to 160 °F (71 °C), and whole cuts of beef, pork and fish to 145 °F (63 °C).
- Chill: refrigerate leftovers within 2 hours (1 hour above 90 °F or 32 °C), and keep your fridge at 40 °F (4 °C) or below.
Also avoid unpasteurized milk and juice, wash produce, and if pregnant, avoid high-risk foods such as deli meats unless heated until steaming. Do not prepare food for others while sick and for 48 hours after symptoms end.
Frequently asked questions
How long does food poisoning last?
Most food poisoning lasts 1 to 3 days. Toxin-related illness can pass within 24 hours, while Salmonella or Campylobacter may last up to a week, and E. coli O157 up to 10 days. See a doctor if symptoms last more than 3 days.
How soon after eating do you get food poisoning?
It depends on the cause. Toxins from Staph aureus or Bacillus cereus can cause vomiting within 30 minutes to a few hours. Norovirus usually starts in 12 to 48 hours, Salmonella in 6 hours to 6 days, and Campylobacter or E. coli in 2 to 5 days.
What should I eat after food poisoning?
Start with fluids, then bland foods like toast, crackers, rice, bananas, applesauce, soup and eggs as you feel able. Return to your usual diet within a day or two. Avoid alcohol, fatty or spicy foods and large amounts of caffeine until your stomach settles.
When should I go to the doctor for food poisoning?
See a doctor for bloody diarrhea, fever over 102 °F (38.9 °C), vomiting that prevents keeping fluids down, diarrhea lasting more than 3 days, or signs of dehydration. Pregnant people, young children, older adults and those with weak immune systems should seek care sooner.
Is food poisoning contagious?
Some causes are. Norovirus, Salmonella, Shigella and E. coli can spread from person to person through contaminated hands and surfaces. Toxin-related food poisoning, such as from Staph or Bacillus cereus, is not contagious. Wash your hands well and avoid cooking for others while sick.
Sources
This guide was written from current patient and clinical guidance, including:
- CDC: Food Poisoning Symptoms
- CDC: Four Steps to Food Safety
- US Food and Drug Administration: Foodborne Pathogens
- MedlinePlus: Foodborne illness
- Infectious Diseases Society of America: 2017 Guidelines for the Diagnosis and Management of Infectious Diarrhea