What Foods Trigger IBS


Irritable bowel syndrome (IBS) is a condition of the gut where there is tummy pain associated with changes in bowel habits, stool frequency, and consistency. People suffering from IBS can have diverse presentations, and their symptoms themself can vary with time. No single medication or dietary plan works for everyone with IBS, and the treatment and management of symptoms are tailored according to individual needs.

A crucial part of managing IBS symptoms is recognizing foods in one's diet that trigger or worsen the symptoms and reducing or avoiding their intake. Keeping a diary of things you eat and symptoms you get after can help recognise the triggers in your diet. Avoiding these foods can markedly improve IBS symptoms.

General dietary tips for IBS include having regularly scheduled small meals, avoiding skipping meals, reducing spicy and fatty food, and limiting caffeine and alcohol. If you have IBS with diarrhoea, your doctor will advise you to reduce your intake of fiber, and if you have IBS with constipation, your doctor will advise you to increase the intake of fiber in your diet.

Many people with IBS have a good tolerance for the lactose protein in milk and other dairy products so avoiding them is highly controversial, but opting for lactose-free alternatives can improve symptoms of IBS in people with lactose intolerance. 

Your doctor might also recommend restricting a high FODMAP diet and opting for foods that have low FODMAPs. FODMAP refers to a group of carbohydrates (sugars) that are found in different foods. These sugars are difficult for the gut to digest and cause aggravation of IBS symptoms. A few examples of high FODMAP foods are wheat bread, wheat cereals, onions, garlic, apples, milk, cheese, and sugar-free confectionery.

Complete restriction and avoidance of food can also lead to nutritional deficiencies. If you think that you have IBS, or that your symptoms get worse after eating certain foods, it is important to consult your GP who can refer you to a dietitian for a nutritional plan tailored to your personal needs.

Irritable bowel syndrome (IBS)

Irritable bowel syndrome or IBS is a chronic condition and can last for days, weeks, or even months. People who suffer from IBS experience pain with defecation (passing stool), and experience either severe tummy pain before a bowel movement which is relieved by passing stool, or tummy pain during the bowel movement itself. The pain is associated with changes in the stool frequency (number of times stool is passed in a week) and consistency (hard or loose stools).


  • Tummy pain – with defecation
  • Diarrhoea or constipation — usually one is predominant, but it can also alternate in some people.
  • Bloating – swelling of the tummy
  • Flatulence – passing excessive wind
  • Tenesmus – feeling an urgent need to pass stool even when the bowel is empty


Based on the stool frequency and consistency, IBS is predominantly of two types:

  1. IBS with predominant diarrhea – in this type, people have an increased frequency of stool, which is of loose consistency 
  2. IBS with predominant constipation — in this type, people have a decreased frequency of stool which is of hard consistency.

These types can interchange, that is, a person originally having diarrhea can have constipation later.


The exact cause is not known, but it is considered to be a defect in the brain to gut signaling, which causes abnormal gut motility and increased gut sensitivity. It is called a functional disorder, which means that no organic abnormality is noted.1

Foods that can trigger IBS

It is a general concept that diet plays a crucial role in the development of IBS symptoms. Dietary guidance is important for people with IBS, which should be individualized as everyone has a different tolerance to different food items. Recognizing the triggers in your diet can help you avoid foods that worsen your symptoms.

Common dietary triggers are:

  1. Gluten – Avoiding foods with gluten has been shown to improve symptoms of IBS even in people that don't have gluten sensitivity. Common gluten sources include wheat, pasta, cereals, and bakery products.
  2. Processed foods
  3. Caffeine– Caffeine stimulates and increases gut motility and can worsen the symptoms of IBS, especially in people with IBS with predominant diarrhea. It is best to avoid or reduce the intake of beverages like coffee, soft drinks/sodas, and tea.
  4. Carbonated drinks – Increase bloating and gas.
  5. Alcohol – Drinking alcoholic beverages, especially binge drinking, has been shown to worsen symptoms of IBS the next day, specifically a worsening of nausea, diarrhea, and tummy pain.
  6. Dairy – Having a lactose-free diet has been shown to improve symptoms of IBS, especially in people with lactose intolerance. 
  7. High-fat – High-fat diets can worsen IBS symptoms. 
  8. Spicy food– Increases the prevalence and symptoms of IBS particularly if consumed in high amounts.2


Recent studies have shown that foods that are rich in FODMAPs cause IBS symptoms.

What are FODMAPs?

FODMAPs stands for Fermentable Oligo-, Di-, Monosaccharides, and Polyols. These are a group of carbohydrates (sugars) that are present in food and are difficult for the gut to digest. When foods that have high FODMAP are consumed by people with IBS, these sugars are not digested properly, causing diarrhea. The undigested sugars are also then fermented (broken down) in the gut by gut bacteria, producing gas.

Your GP and dietitian can recommend you swap food with high FODMAP for foods with low FODMAP, while also ensuring that there is no development of nutritional deficiency.2,3

Best foods for IBS

  1. High fiber diet – Increased fiber intake has been shown to reduce and improve symptoms in people with IBS with constipation.
  2. Lactose-free alternatives to milk and milk products, soy milk, almond milk
  3. Gluten-free diet – gluten-free flour, pasta, and cereals
  4. Low-fat diet – low-fat spreads, butter, and ghee
  5. Meat, poultry, eggs, fish, and vegetarian protein foods
  6. Low FODMAP diet – a low FODMAP diet is implemented under expert guidance, as it is done in phases. 

Non-dietary triggers of IBS


Stress is a major non-dietary trigger of IBS. Psychological stress has been shown to have an impact on gut sensitivity and mobility which can cause flare-ups of symptoms of IBS. Managing stress is also an important aspect of IBS management.4

Certain medications

People with IBS cannot tolerate certain medications such as:

  • Antibiotics
  • Sorbitol-containing medications such as cough syrups


IBS symptoms like bloating get aggravated during menstruation.  

When to seek medical attention

Your GP will make a diagnosis of IBS after ruling out other causes of tummy pain and changes in the stool.

Seek medical attention if you are experiencing any of the following symptoms:

  • Unexplained weight loss
  • Blood in stool
  • Lethargy and tiredness
  • Lumps and bumps anywhere in the body
  • Decreased appetite 
  • Drenching sweats during the night
  • Dizziness
  • Palpitations – feeling your heart beat very loudly
  • Fever
  • Family history of inflammatory bowel disease (IBD) and coeliac disease.

It is also important to seek medical attention if you are having symptoms of IBS and are above 50 years of age, as IBS is commonly seen in young people. 


IBS is a condition of the gut characterized by tummy pain and changes in bowel habits, that is, prolonged diarrhea or constipation. Many food items in one’s diet have been shown to aggravate or flare up symptoms of IBS, so avoiding these foods can help control it. No single diet plan works for everyone with IBS. If you are suffering from IBS, it is best to keep a diary of the symptoms you experienced and the food you ate in order to recognize the triggers in your diet. Making a nutritional plan after a discussion with your GP and a dietitian can help avoid any nutritional deficiencies that can occur as a result of dietary restrictions.


  1. Ford AC, Sperber AD, Corsetti M, Camilleri M. Functional gastrointestinal disorders 2 irritable bowel syndrome. Lancet. 2020 Nov 21;396(10263):1675-88.
  2. Rej A, Aziz I, Tornblom H, Sanders DS, Simrén M. The role of diet in irritable bowel syndrome: implications for dietary advice. Journal of internal medicine. 2019 Nov;286(5):490-502.
  3. Bellini M, Tonarelli S, Mumolo MG, Bronzini F, Pancetti A, Bertani L, Costa F, Ricchiuti A, de Bortoli N, Marchi S, Rossi A. Low fermentable oligo-di-and mono-saccharides and polyols (fodmaps) or gluten free diet: What is best for irritable bowel syndrome?. Nutrients. 2020 Nov 1;12(11):3368.
  4. Qin HY, Cheng CW, Tang XD, Bian ZX. Impact of psychological stress on irritable bowel syndrome. World journal of gastroenterology: WJG. 2014 Oct 10;20(39):14126.
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Aatika Owais

Bachelor of Medicine & Bachelor of Surgery (MBBS); Dow University of Health Sciences, Karachi, Pakistan

Dr. Aatika is a junior doctor, with an avid interest in surgery and clinical research, having hospital experience complimented with excellent patient management skills.
She has experience in writing research articles and peer-reviewing articles for medical journals.
She is registered with Pakistan Medical Council and with the General Medical Council, UK as a fully licensed doctor. She is an aspiring neurosurgeon and believes in utilizing research to uncover new therapies and procedures to deliver high-caliber patient care.

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