What Causes IBS: Common Triggers

Irritable Bowel Syndrome (IBS) causes are not well understood, because it’s not caused by any known medical condition or disease. There is no specific food or substance that triggers IBS symptoms. 

Functional gastrointestinal (GI) conditions like IBS are often thought to be disorders of the brain-gut interaction, how the brain and gut communicate and work together. 

Doctors believe that there are multiple factors that combine to cause IBS, and that combination of factors is unique to each IBS sufferer. Common factors that can trigger IBS symptoms include: 

  1. Mental/emotional stress
  2. Certain foods and diet changes
  3. Medications
  4. Infections
  5. Physical trauma
  6. Family history

Once you can identify what triggers your IBS symptoms, you may be able to avoid them in the future. You’ll also know if a change in lifestyle will help alleviate your symptoms.

1. Mental Stress

Mental stress can be one of the biggest factors in triggering IBS symptoms. Common sources of stress can come from work, problems at home, and financial stressors. Mental health disorders such as depression and anxiety and emotional distress are also potential triggers. 

Psychological distress will activate the brain’s response to stress – cortisol. Cortisol is released into the bloodstream and has many downstream effects.

Stress hormones send messages throughout the body, and a response to stress can manifest in several different ways, including cardiovascular, urinary, gastrointestinal, or neurologic symptoms. You can develop symptoms such as chest pain, headaches, urinary urgency, abdominal pain, diarrhea, or difficulty sleeping as a response to mental or emotional distress.

Gastrointestinal symptoms are very commonly associated with stress.  These include:

  • Abdominal pain
  • Heartburn
  • Indigestion
  • Nausea
  • Vomiting
  • Diarrhea
  • Constipation

Finding ways to reduce and manage stress can help provide relief and improve daily life. Common ways to avoid stress-induced IBS symptoms include: 

  • Meditation
  • Yoga
  • Exercise
  • Cognitive behavioral therapy or psychotherapy
  • Relaxation techniques

There are many alternative IBS treatment options that you can try to improve your quality of life. 

2. Certain Foods and Diet Changes

Sensitivities to foods and dietary changes could lead to IBS symptoms. A common example of certain foods are ones that are high in FODMAPs, which are fermentable carbohydrates (sugars) found naturally in many different foods. 

These types of carbohydrates are poorly absorbed, so they pass through the small intestine without being digested properly. They then reach the colon where gut bacteria ferment them, resulting in gas and bloating. 

The gas stretches the intestinal walls of people with IBS, which leads to pain and discomfort.

Common high FODMAP foods include: 

  • Fruits – Apples, cherries, mango, nectarines, peaches, pears, plums, watermelons
  • Vegetables – Artichoke, asparagus, broccoli, cabbage, cauliflower, garlic, green peas,, onions
  • Dairy and Alternatives – Cow’s milk, custard, ice cream, soy milk (made from whole soybeans), yogurt, soft cheeses
  • Protein Sources – Some marinated meats/poultry/seafood, some processed meats, most legumes like beans, chickpeas and lentils
  • Breads and Cereals – Wheat/rye/barley based breads, breakfast cereals, biscuits and snack products
  • Sugars/Sweeteners – Honey, high fructose corn syrup, sugar free candy, carbonated drinks, products containing sweeteners like sorbitol, mannitol, isomalt, maltitol and xylitol
  • Nuts and Seeds – Cashews, Pistachios

Many people with IBS will try a low FODMAP diet plan to try and keep their symptoms at bay. Some patients find symptom relief by increasing daily fiber intake and drinking more water.

Keeping a food diary will help you recognize food sensitivities and food intolerances that might cause abnormal bowel movements. For example, fried or spicy foods can irritate your digestive tract or you may identify a few high FODMAP foods that cause distress.

Eating too quickly, chewing gum, or drinking carbonated drinks can lead to swallowed air, which may increase gas, bloating and abdominal discomfort.

Learn more about IBS Diet Plans.

3. Medications

Some prescription medications and over-the-counter medications can affect how your digestive system functions.

Common drugs include antibiotics, antihistamines, antacids, laxatives, antidepressants, blood thinners, birth control pills, cough syrups, steroids, diuretics, and narcotics.  Common GI side effects include nausea, bad taste in the mouth, dry mouth, constipation or diarrhea.

Always discuss medications and treatments with your doctor. Whether you are starting new medications or supplements, or thinking about switching to a different drug, always consult with your physician first. 

4. Infections

Bacterial infections can often cause IBS symptoms like diarrhea either due to intestinal inflammation or increased secretion of fluid into the gut.  Following a bacterial or viral gastroenteritis/infection, IBS can develop.

There are trillions of bacteria in the gut and they perform a variety of functions in the large intestine. When these bacteria migrate into  the small intestine in a condition called small intestinal bacterial overgrowth (SIBO), gas and bloating can occur. 

See your doctor if you think you may have a gastrointestinal infection.  Further testing and treatment may be needed.

5. Physical Trauma or Surgery

Physical trauma is another possible trigger for IBS symptoms. Surgery causes stress on the body.  Often after surgery, narcotic pain medications are used, which can cause constipation and abdominal pain.  Surgery on the intestines often results in the bowels temporarily slowing down, which can result in nausea, vomiting, abdominal pain, or constipation.

Intense exercise can sometimes trigger diarrhea or abdominal pain and cramping.  During exercise, blood is diverted away from the intestines to help supply oxygen to the muscles. 

Exercise still benefits the body and can reduce stress, so it shouldn’t be avoided. The key is to exercise in moderation and not increase your workout intensity suddenly. 

6. Family History

If someone close to you has IBS, you are 2-3 times more likely to have IBS.  Up to 20% of all cases of irritable bowel syndrome have been linked to family history.  A Mayo Clinic study researched over 100 genetic variants in over 60 genes.  Findings suggest that IBS can be hereditary.

IBS Causes Summary

The etiology of IBS is caused by many factors, including genetics, environment, lifestyle choices, medication use, food sensitivities, and other health conditions. There isn’t one single cause, but rather several contributing factors.

The good news is that most people who suffer from IBS don’t need surgery to treat their condition. They just need to learn ways to manage their symptoms naturally.

The cause of IBS is not fully understood, but is believed to develop as a result of disordered gut-brain interaction, exacerbated by physical, emotional, or psychological distress and the diet.  The symptoms of IBS may fluctuate over time.

Finding the right treatment for your IBS may take time and trial and error.  There are several medications available that can be used to help manage IBS symptoms.  Lifestyle changes, including dietary changes and exercise/stress reduction techniques, may also help manage your IBS.

  • American College of Gastroenterology: Irritable Bowel Syndrome
  • National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK): IBS Symptoms & Causes
  • MedlinePlus: Irritable Bowel Syndrome
  • University of North Carolina: Stress and the Gut
  • Harvard Medical School: Stress and the Sensitive Gut
  • Monash University: FODMAPs and Irritable Bowel Syndrome
  • WebMD: IBS Triggers and How to Avoid Them
  • University of Southern California: Bacteria May Be the Cause of IBS
  • Very Well Health: Managing Exercise and Your IBS
  • National Institutes of Health: The Role of Genetics in IBS 
  • https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3056499/

Written and Medically Reviewed By

  • Kelly Chow

    Kelly first experienced IBS symptoms at the age of 24 with major-to-severe symptoms. She underwent all types of tests and experimented with many treatments before finally finding ways to manage her symptoms. Kelly has written and shared ebooks and Gluten-Free diet plans that she has used to live life like she did before IBS.

  • Julie Guider, M.D.

    Dr. Julie Guider earned her medical degree from Louisiana State University School of Medicine. She completed residency in internal medicine at the University of Virginia. She completed her general gastroenterology and advanced endoscopy fellowships at University of Texas-Houston. She is a member of several national GI societies including the AGA, ACG, and ASGE as well as state and local medical societies.