Bloated after Food Poisoning?

If you are still bloated 8 weeks after food poisoning you are not alone. Approximately 1 in 9 people develop post-infectious IBS after food poisoning.

Acute symptoms can settle within days, yet the after-effects on your gut lining, gut bacteria, and gut motility may persist for much longer.

When that happens, meals that used to feel fine can suddenly leave you swollen, windy and uncomfortable.

This guide explains, why bloating can continue after food poisoning, how post-infectious IBS fits in, when temporary lactose intolerance is the main driver, where SIBO comes into the picture, and what a recovery plan looks like.

What is food poisoning?

Food poisoning happens when you eat or drink something contaminated with germs or toxins. Common bacterial causes include Campylobacter from undercooked poultry, Salmonella from eggs and chicken, certain strains of E. coli from burgers/mince and leafy greens, Clostridium perfringens from food kept warm too long, and Staphylococcus aureus or Bacillus cereus when food is handled or stored improperly. Viruses also cause a large share of cases—especially norovirus, which spreads easily via hands and surfaces. Parasites such as Giardia or Cryptosporidium can come from unsafe water or foods washed in it. Some illnesses are due to natural or chemical toxins rather than live germs, such as scombroid or ciguatera from certain fish, or mushroom toxins.

Contamination usually happens through poor hygiene, cross-contamination between raw and ready-to-eat foods, inadequate cooking, slow cooling, or keeping food in the “danger zone” (about 5–60 °C) where germs multiply quickly. Higher-risk items include unpasteurised milk/cheese, raw or undercooked eggs and poultry, burgers/minced meats, deli foods, rice left out too long, shellfish from polluted waters, and fresh produce rinsed in unsafe water.

What causes bloating after Food poisoning?

There are a number of reason why you are bloated after Food poisoning.

Firstly, food poisoning irritates the lining of the small intestine.

Your surface enzymes that help with digestion are reduced for a short time. This means small amounts of carbohydrate (including lactose) and some fats may not be fully digested. During this time you may feel bloated after meals.

As the infection settles, the lining repairs. However, it can take a few weeks to work normally again.

The nerves in the gut are also more sensitive. Normal amounts of gas will feel uncomfortable. Large or late meals often make this worse.

Gut movement can slow after an infection. This gives bacteria more opportunity to ferment sugars and fibres, producing gas that stretches a sensitive gut and causes bloating.The “housekeeping” waves that move food and gas along may be weaker for a while. When movement is slow, food and by-products stay longer in the small intestine. Bacteria have more time to ferment them, which makes gas and leads to bloating. If these waves slow or fail to complete, food residues and microbial by-products linger in the small intestine longer than they should.

Your gut bacteria may change as well. Helpful types can drop and gas-producing types can increase, especially if you took antibiotics. Foods that were fine beforesuch as onions, beans or regular dairymay now cause wind and bloating.

These changes are usually temporary. Most people improve with small, regular meals, simple well-cooked foods, a short walk after eating, and if dairy triggers symptoms lactose-free options for 4 to 6 weeks.

What are the symptoms of food poisoning?

Food poisoning usually starts with feeling sick. Nausea, vomiting, diarrhoea and tummy cramps are common. Some people also get a fever, headache, aching muscles and loss of appetite. You may feel bloated and gassy. Stools can be watery; rarely they can be bloody.

Dehydration is the main risk. Signs include a dry mouth, dark urine, passing little urine, dizziness or feeling faint. Children, older adults, pregnant people and anyone with a weaker immune system can get dehydrated quickly.

Most cases can be managed at home with fluids and rest. See your GP or seek urgent care if you have blood in your stool, a high fever that does not settle, severe or worsening abdominal pain, signs of dehydration, symptoms that last more than 48–72 hours without improvement, or if you are in a higher-risk group.

How long does food poisoning last

For most people, symptoms improve quickly. Many feel better within 24–72 hours. Some bugs last a little longer. Norovirus is usually one to three days. Common bacterial infections often settle within four to seven days. After the sickness passes, it is normal to feel tired and to have a sensitive gut for a short time.

How to reduce bloating after food poisoning

If you’ve had food poisoning, bloating often lingers for a few weeks. You can usually manage this at home.

Most people improve within 2 to 8 weeks.

Choose simple foods at first—rice, potatoes, lean proteins such as chicken, and well-cooked vegetables. This is easier on a sensitive gut.

Sip fluids through the day. Water and herbal teas are best. Avoid fizzy drinks and alcohol until you’re feeling better, as they can increase gas.

Try a short walk (10–15 minutes) after meals. Gentle movement helps your gut move food and gas along. Avoid lying down for at least an hour after eating.

If dairy seems to set you off within an hour or two, switch to lactose-free milk and yoghurt for 4–6 weeks, then re-test your tolerance. This is common after a stomach bug and usually improves as the gut lining heals.

Peppermint or ginger tea may soothe cramps and wind.

Reintroduce foods gradually as you improve. Add one new food at a time, in small amounts with meals, and build up if it sits well.

Switch to lactose-free dairy for a few weeks if milk is a trigger and ,watch portion size of very high-FODMAP foods such as beans and pulses brussel sprouts, onions and garlic, and then re-introduce them gradually as motility and comfort improve.

Post-infectious IBS and bloating: what it is and how to recognise it

When IBS-type symptoms begin after a confirmed gut infection and persist for months, clinicians use the term post-infectious IBS (PI-IBS).

The hallmark is a combination of abdominal discomfort or pain, bloating and a change in bowel habit that began after an episode of gastroenteritis.

Symptoms include low-grade inflammation, a hypersensitive intestinal lining and altered motility. For some people the pattern is diarrhoea-predominant; for others it alternates or causes constipation. Some people describe constant bloating after food poisoning even if they drink water!

What is causing constant gas and bloating?

if your bloating and bowel changes continue beyond eight to twelve weeks after the initial illness and there are no red-flag signs of something more serious, PI-IBS becomes a real possibility.

Recognising it is helpful because you can then run specific tests such as lactose malabsorption or a Hydrogen and Methane breath test for SIBO or a parasite test.

Temporary lactose intolerance after food poisoning

Secondary lactose intolerance is extremely common after food poisoning and gastroenteritis. The infection can shear off a portion of the lactase enzymes that sit on the tips of the small-intestinal villi.

Until they regrow, lactose, the milk sugar found in regular milk, ice cream and many desserts passes through the small intestine undigested and becomes food for microbes, generating gas and drawing fluid into the bowel.

This means you may experience more wind, gurgling, bloating and sometimes urgency, usually beginning thirty to one hundred and twenty minutes after a lactose-rich food.

The good news is most people notice clear improvement over four to six weeks as the lining recovers.

In the meantime, try to switch to lactose-free milk and yoghurt, to choose hard or aged cheeses that are naturally very low in lactose, and to keep portions modest while symptoms settle.

When you feel ready, reintroduce dairy in a structured way: start with small amounts, pair dairy with meals rather than on an empty stomach, and step up gradually from lactose-free to live/plain yoghurt and then to regular milk.

If you are unsure whether lactose is the issue or if symptoms persist despite making these swaps, we can provide you with a lactose breath test. Do contact our clinic and we cn provide you with a lactose breath test- the fee is £165.

Post-meal bloating with lots of gas may point more towards small-intestinal fermentation (SIBO), consider SIBO testing or discuss with your functional medicine practioner.

SIBO after food poisoning: when to Test

SIBO stands for Small Intestinal Bacterial Overgrowth, which means an excess of bacteria where relatively few should live. If your bloating consistently starts early after meals, typically within thirty to ninety minutes and is accompanied by a lot of gas or belching, small-bowel fermentation may be part of the picture.

In that case, a glucose or lactulose breath test for SIBO is worth discussing because a positive result would change your next step.

Food poisoning can leave the small intestine moving more slowly than normal for a few weeks. Between meals, the gut runs a “housekeeping” wave (the migrating motor complex, MMC) that clears leftover food and gas.

After an infection, this wave can be weaker or irregular. When clearance is slow, bacteria have more time to stay and multiply in the small intestine, which is how small intestinal bacterial overgrowth (SIBO) develops.

Some food-poisoning bacteria make a toxin called CdtB. In some people, the immune response to this toxin also targets a protein called vinculin, which helps coordinate the MMC. This can keep motility off-rhythm after the bug has gone, making overgrowth more likely.

The infection also irritates the lining of the small intestine and changes the balance of gut bacteria. Helpful species can dip and gas-producing species can rise, especially if antibiotics were needed. If you then graze all day, lie down soon after meals, or use acid-suppressing medicines, bacteria have an even easier time lingering in the small bowel.

Not everyone gets SIBO after a stomach bug. You’re more at risk if you had a severe infection, needed antibiotics, already have constipation or slow transit, use proton-pump inhibitors, or have had abdominal surgery that affects gut flow.

Clues that point towards SIBO are early bloating after meals (often 30–90 minutes),belching, visible distension, and sometimes constipation when methane-producing microbes are high (others have looser stools). If this sounds like you, a glucose or lactulose breath test is a practical next step. If your test is positive you will need to have treatment, a short antimicrobial protocol prescribed by a clinician and follow a low-FODMAP diet for 4 weeks

Parasites and ongoing bloating

Some cases of “food poisoning” are caused by parasites rather than bacteria or viruses. In the UK the most common are Giardia and Cryptosporidium. Less often, people pick up Entamoeba histolytica or Cyclospora after travel. These infections can cause bloating that lasts longer than a typical stomach bug.

Think about a parasite if diarrhoea and bloating continue for more than one to two weeks, if stools are pale, greasy or very smelly, or if symptoms began after travel, camping, swimming in lakes or streams, or drinking untreated water. Tiredness, gurgling, excess wind and cramping are common. Some people lose weight or notice symptoms come and go.

Parasite Testing is done with stool sample. We offer thisis our clinic

FAQs: bloating after food poisoning

Is bloating after food poisoning normal?
Yes. The gut lining is irritated and gut movement slows for a while, so normal amounts of gas feel like pressure. Most people improve over 2–8 weeks with small, regular meals, gentle movement after eating, and simple, well-cooked foods. See your GP sooner if there are red flags (blood in stool, weight loss, persistent fever, severe pain, night-time symptoms).

Could this be post-infectious IBS?
It can be. If bloating and a change in bowel habit began after a stomach bug and continue beyond 8–12 weeks (with no red flags), clinicians often use the term post-infectious IBS (PI-IBS). A simple routine usually helps first; selective tests (e.g., SIBO or lactose breath tests) are considered only if results would change your plan. NICE+1

Why does dairy make me bloat now?
After gastroenteritis, the gut can temporarily lose lactase, the enzyme that digests milk sugar (lactose). This is called secondary lactose intolerance and commonly settles in 4–6 weeks. Using lactose-free milk/yoghurt and hard cheeses for a short time is reasonable, then re-test tolerance. NHS Inform+1

When should I test for SIBO?
Consider a breath test if your bloating starts 30–90 minutes after meals with prominent gas/belching, or if constipation has a methane pattern. If positive, a short, targeted treatment plus motility support can help, followed by a rebuild phase to widen the diet. Lippincott Journals

What diet changes actually help?
Start with a short “calming” phase of simple, well-cooked foods and regular mealtimes. Some people benefit from a low-FODMAP trial guided by a clinician, with structured re-introductions to avoid long-term restriction. A gentle soluble fibre such as PHGG can reduce bloating for some people when introduced slowly. PubMed+2Gastro Journal+2

Do peppermint capsules help?
Enteric-coated peppermint oil can reduce overall IBS symptoms for some adults, but it may worsen reflux in sensitive people. Use under clinician/pharmacist guidance. BioMed Central

References

1. NICE (UK): Irritable bowel syndrome in adults—diagnosis and management (CG61). Last reviewed 30 April 2025. Recognises post-infectious pathways and outlines first-line investigations in primary care.
2. ACG Clinical Guideline: Management of Irritable Bowel Syndrome (2021). Comprehensive guidance on IBS diagnosis and management, including diet, peppermint oil and fibre. Lippincott Journals
3. Post-infection IBS meta-analysis (Ghoshal UC, 2021/2022). Pooled prevalence of PI-IBS ≈ 11.5% after acute gastroenteritis. PMC+1
4. Campylobacter cohort and PI-IBS risk (Berumen A, Clin Gastroenterol Hepatol 2021). About 21% developed PI-IBS after Campylobacter infection. PubMed+2CGH Journal+2
5. NHS Inform (2025): Lactose intolerance. Lists gastroenteritis as a common cause of secondary lactase deficiency; practical patient advice. NHS Inform
6. Low-FODMAP evidence (Halmos EP, Gastroenterology 2014; Böhn L, 2015). Controlled trials showing symptom reduction in IBS with a structured low-FODMAP diet. PubMed+1
7. PHGG randomised trial (Niv E, Nutrition & Metabolism 2016). Support for 6 g/day PHGG improving bloating/gas in IBS. BioMed Central
8. ACG Clinical Guideline: Small Intestinal Bacterial Overgrowth (Pimentel M, 2020). Diagnostic criteria, breath testing methods and treatment overview. Lippincott Journals+1
9. Peppermint oil meta-analysis (Alammar N, BMC Complement Med Ther 2019). Peppermint oil safe and effective for global IBS symptoms and pain in adults. BioMed Central+1
   
   
   Author – Victoria Tyler BSc Hons MBANT
   Victoria Tyler owns and runs two busy clinics : Nutrition and Vitality and the IBS and Gut Disorder Clinic.
   Nutrition and Vitality, along with the IBS and Gut Disorder Clinic, were founded with the goal of helping patients alleviate IBS symptoms by uncovering and addressing the root causes of their digestive issues.
   As a Registered Nutritional Therapist, Victoria holds a BSc (Hons) in Nutritional Therapy and has trained with the Institute of Functional Medicine. She is also accredited by BANT and CNHC.
   Before transitioning into health, Victoria earned a degree in Economics and an MBA, working with corporations including Canon and Vodafone. However, her own health challenges led her to pursue a career in Nutritional Therapy.
   With a passion for learning, Victoria is committed to staying at the forefront of Functional Medicine. She helps patients manage IBS and other digestive disorders, including SIBO, Candida, and IBD, by identifying and addressing their root causes.
   Victoria strongly believes that every symptom has an underlying cause, and there is always a solution to every health condition. To learn more, or to see patient reviews, visit Victoria’s profile on Google.
   DISCLAIMER: The information provided in this article is intended for general informational purposes only and should not be construed as medical advice, diagnosis, or treatment. The products and methods mentioned are not a substitute for professional medical advice from a trained healthcare specialist. Always seek the guidance of your doctor or other qualified health professional with any questions you may have regarding your health or a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website. Use of the information and products discussed is at your own risk.