How Long Does Food Poisoning Last? A Timeline by Germ

Most food poisoning lasts a few hours to a few days, and most cases clear within a week without treatment^[1]. The germ sets the clock. Staph toxin illness usually passes within 24 hours^[2], norovirus within 1 to 3 days^[3], Salmonella in 4 to 7 days^[4], and Campylobacter can run for up to 10 days^[5].

This guide gives the onset and duration for each common cause, the stages of a typical case, why some cases drag on, how long you stay contagious, and what helps recovery.

Get medical help promptly if you have bloody diarrhea, diarrhea lasting more than 3 days, a fever over 102°F, vomiting so frequent you cannot keep liquids down, or signs of dehydration such as little urine, a dry mouth or dizziness when you stand^[6]. Blurred vision, tingling, weakness or trouble swallowing after a meal can signal botulism and need an emergency room right away^[7].

How long does food poisoning last, germ by germ?

Duration depends on what made you sick. Preformed toxins tend to cause short, sharp illness, while bacteria and parasites that infect the gut usually last longer. The table below uses the FDA's and CDC's onset and duration ranges for common US causes.

Staph illness is short because the toxin is already in the food when you eat it. Cooking kills staph bacteria but does not destroy the toxin they made, and antibiotics do not help because they do not affect the toxin^[2]. Infections such as Salmonella take longer on both ends: up to 6 days to start and usually 4 to 7 days to clear^[4].

How long does food poisoning take to kick in?

Food poisoning can kick in anywhere from 30 minutes to several weeks after you eat, depending on the cause^[6][5]. Knowing the gap helps you work out which meal, and which germ, is the likely source.

How soon after eating can you feel sick?

Toxins work fastest. Staph can start within 30 minutes to 8 hours and C. perfringens within 6 to 24 hours^[6].

Slower germs make the last meal a poor suspect. Salmonella can take up to 6 days, Campylobacter 2 to 5 days, and invasive Listeria illness usually appears within 2 weeks^[6][8]. Hepatitis A averages 28 days^[5]. Contaminated food also tends to look, smell and taste normal, so a "bad" taste is not a reliable clue^[9].

How soon after food poisoning do you vomit?

With a toxin, vomiting often comes first and fast. Staph toxin brings a sudden onset of severe nausea and vomiting, often with cramps^[5], within 30 minutes to 8 hours of eating^[2].

C. perfringens is the exception among fast causes: it brings cramps and diarrhea, but vomiting and fever are not common^[6]. Vomiting is also more common in children with norovirus, while adults more often get diarrhea^[5].

Food poisoning or a stomach bug: what's the difference?

Timing is the best clue. Illness within hours of a meal points to a toxin, while norovirus, the usual "stomach bug," starts 12 to 48 hours after exposure^[3]. Our stomach flu vs. food poisoning guide compares the other clues.

What are the stages and typical timeline of food poisoning symptoms?

A typical case moves through four stages. How long each one lasts depends on the germ.

1. Incubation. The symptom-free gap between eating and feeling ill, from 30 minutes for staph toxin to weeks for Listeria or hepatitis A^[6][5].
2. Acute illness. Diarrhea, stomach pain or cramps, nausea, vomiting and fever are the most common symptoms^[6]. Diarrhea that lasts under 7 days counts as acute^[10].
3. Recovery. Symptoms ease and appetite returns. Most people recover on their own within a week^[1].
4. After-effects (in some people). A minority develop problems that last weeks, months or longer, such as irritable bowel symptoms or joint pain^[6][1].

How long do vomiting, diarrhea and fever last?

There is no fixed timetable for each symptom, but the cause gives strong hints. Vomiting from a staph toxin rarely outlasts a day, since the whole illness usually lasts 24 hours or less^[2]. Illness from Campylobacter or E. coli O157:H7 can last up to 10 days^[5].

The IDSA guideline uses diarrhea length to sort cases: under 7 days is acute, 7 to 13 days is prolonged, 14 to 29 days is persistent, and 30 days or more is chronic^[10]. The NIDDK already advises adults to see a doctor when diarrhea continues for more than 3 days^[7], so diarrhea that runs past a week should not be waited out.

Fever is common with Salmonella and Campylobacter^[6]. E. coli O157:H7 often causes severe, bloody diarrhea with little or no fever, so a normal temperature does not rule out a serious infection^[5].

Why is my food poisoning lasting so long?

Food poisoning that lasts more than a week usually means a slower germ, a weakened immune system, or a gut that has not yet settled after the infection cleared. Common reasons include:

• A parasite. Cyclospora and Cryptosporidium can cause diarrhea that comes and goes for weeks to months^[5]. The IDSA advises testing for intestinal parasites when traveler's diarrhea lasts 14 days or longer^[10]. See our stool test for parasites guide.
• A lingering bacterial infection. Some people with Salmonella have diarrhea for several months^[4].
• A weakened immune system. Immunocompromised people are more likely to have severe or prolonged illness, and some protozoa can become chronic or relapsing in them^[10].
• Recent antibiotics. The IDSA suggests considering C. difficile testing in people whose diarrhea follows antibiotic use^[10]. Our guide to antibiotics and diarrhea explains why.
• Post-infectious IBS. The infection is gone, but bowel symptoms stay (below).

What food poisoning does to your gut microbiome

Your gut can stay unsettled long after the germ is cleared. In a meta-analysis of 45 studies with 21,421 people, 10.1% met criteria for irritable bowel syndrome 12 months after infectious enteritis, a risk 4.2 times that of people without the infection^[11]. The rate was 41.9% after protozoal or parasitic infections and 13.8% after bacterial ones. Women, people given antibiotics during the illness and people with anxiety had higher risk^[11].

The bacterium involved seems to matter less than once thought. A second meta-analysis found similar post-infectious IBS rates after Campylobacter (12%), Salmonella (12%), Shigella (11%) and E. coli (12%)^[12].

A 2023 review describes how the infection can shift the gut microbiota, weaken the intestinal barrier and leave low-grade inflammation that sustains symptoms^[13]. That review also notes that human data on microbiome-targeted treatment for post-infectious IBS are still scarce^[13]. For the wider picture, see our page on diarrhea and the gut microbiome.

Is food poisoning contagious, and for how long?

Some food poisoning is contagious and some is not. It depends on the germ. Norovirus is very contagious, and you can still spread it for 2 weeks or more after you feel better^[3]. CDC advises staying home for 2 days (48 hours) after symptoms stop^[3].

Salmonella can pass from a person with diarrhea to others through unwashed hands or sexual contact^[9]. The IDSA advises that people with diarrhea avoid swimming, water activities and sexual contact while symptomatic, and wash their hands carefully^[10]. Staph spreads differently: about 1 in 4 people carry it on their skin and in their nose, and it reaches food from unwashed hands^[2].

What is the most effective way to treat food poisoning?

No medicine reliably shortens most food poisoning, so food poisoning recovery rests on staying hydrated. The NIDDK calls fluid and electrolyte replacement the most important treatment^[14].

• Drink small, frequent sips. If vomiting is a problem, sip small amounts of clear liquids. Water, diluted juice, sports drinks and broth work for most adults, and saltine crackers help replace electrolytes^[14].
• Use an oral rehydration solution when needed. Older adults, people with a weakened immune system, children, and anyone with severe diarrhea or dehydration should use an oral rehydration solution such as Pedialyte^[14]. The IDSA recommends reduced-osmolarity ORS as first-line treatment for mild to moderate dehydration at any age^[10].
• Eat when you are hungry. You can usually return to your normal diet once your appetite comes back, even with diarrhea^[14]. Strict diets are not required; our BRAT diet guide covers what to eat instead.
• Use anti-diarrheal medicine carefully. Loperamide may be used by healthy adults with watery diarrhea, but it should not be given to anyone under 18 and should be avoided with fever or bloody diarrhea^[10]. Antimotility drugs may raise the risk of hemolytic uremic syndrome in Shiga toxin-producing E. coli infections^[10].
• Skip antibiotics unless prescribed. They do not help norovirus or staph toxin illness^[3][2]. For some bacterial or parasitic infections, a doctor may prescribe antibiotics or antiparasitic medicine^[14].

What about probiotics? The evidence is mixed. A 2020 Cochrane review of 82 trials (12,127 participants, mostly children) found that probiotics probably make little or no difference to the number of people whose diarrhea lasts 48 hours or more^[15]. The IDSA still gives a weak recommendation that probiotics may be offered to healthy adults and children to reduce symptom severity and duration^[10]. Our page on probiotics for diarrhea covers the strains studied.

Who is more likely to have a longer or more serious case?

Infants and children, pregnant women, older adults and people with a weakened immune system are more likely to get food poisoning and more likely to have severe symptoms or complications^[1]. Diarrhea can dehydrate a newborn or infant severely within a day or two^[7].

Food poisoning while pregnant deserves special care. Listeria often causes only a mild fever and flu-like symptoms, such as muscle aches and fatigue, in pregnant women, but infection during pregnancy can lead to miscarriage, stillbirth, premature delivery or a life-threatening infection in the newborn^[8]. CDC advises seeing a doctor if you are pregnant and have a fever with flu-like symptoms^[6].

What complications can follow food poisoning?

Serious complications are uncommon, and dehydration is the most frequent one^[1]. Others to know about:

• Hemolytic uremic syndrome (HUS). About 5% to 10% of people diagnosed with E. coli infection develop this kidney condition^[6]. It is most common in children under 5^[1]. Warning signs include little or no urine, loss of pink color in the cheeks and inner eyelids, and unexplained bruising^[16].
• Guillain-Barré syndrome. About 1 in 1,000 people with Campylobacter infection develop this nerve condition, which starts with weakness and tingling, usually in both legs^[17].
• Reactive arthritis. In a meta-analysis of 24 studies, about 2.6% of people developed joint inflammation after Campylobacter, Salmonella, Shigella or Yersinia infection, with wide variation between studies^[18]. After Salmonella, it can last months or years^[4].

When to see a doctor: signs of severe food poisoning

Seek medical care right away if you have:

• Bloody, black or tarry stools, or blood in your vomit^[7]
• Diarrhea lasting more than 3 days, or six or more loose stools in a day^[7]
• A fever over 102°F^[6]
• Vomiting so often that you cannot keep liquids down^[6]
• Signs of dehydration: very little urine, dark urine, extreme thirst, or dizziness or fainting when you stand^[7]
• Confusion, severe belly or rectal pain, or nervous-system symptoms such as blurred vision, tingling or weakness^[7]
• Any symptoms if you are pregnant, an older adult, or have a weakened immune system^[7]

For a child, call a doctor if diarrhea lasts more than a day, an infant has any fever, or the child seems unusually tired or irritable^[7]. CDC also advises care when diarrhea or vomiting lasts more than 2 days with Campylobacter, Salmonella or E. coli infection^[19][4].

This article is for general educational purposes and is not medical advice. The time ranges above are typical, not guarantees, and only a clinician, sometimes with stool testing, can identify the cause of your illness. Talk to a qualified healthcare professional about vomiting or diarrhea that is severe or persistent, particularly if you are pregnant, immunocompromised, taking prescription medication, or managing a diagnosed condition.