Irritable bowel syndrome (IBS) risk factors and causes

Irritable bowel syndrome (IBS) is one of the most common functional gastrointestinal disorders in the world. Several factors can increase a person’s risk of developing this condition, as discussed in this article.

A man experiencing abdominal pain after trying out a period cramp simulator

Key takeaways:

  • Irritable bowel syndrome is a gastrointestinal disorder mainly caused by poor or inharmonious signaling between the brain and the gut, also called the brain-gut axis. 
  • Signs of IBS include diarrhea, bloating, constipation, excessive bowel movements, and excessive flatulence. 
  • Some IBS risk factors can include age, stressful early life experiences, mental disorders, and bacterial infections. IBS is also more common in females and young people.

Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder characterized by abdominal pain or discomfort with altered bowel habits.

A recent research study shows that about 9% to 23% of the world's population has IBS, and it is particularly common in low- and middle-income countries in the continents of Africa, Asia, and South America. Cases of IBS have also been seen in developed countries like the U.S., Canada, and Israel.

Studies have shown that IBS is more prevalent in females than it is in males, as females are 1.5 to 2 times more likely to have the condition. IBS is also more common in people younger than 60 years.

What causes irritable bowel syndrome (IBS)?

Health experts are not sure of the exact cause of IBS. But some of them suggest that IBS may be caused by a combination of one or more different health problems in individuals. Others also believe that functional gastrointestinal disorders such as IBS may be caused by poor or inharmonious signaling between the brain and the gut, i.e., the brain-gut axis.

The brain-gut axis is a communication/signal pathway that comprises certain nerves that send vital signals/neurotransmitters such as norepinephrine, serotonin, glutamate, GABA, or acetylcholine between the two organs (brain and gut) to generally oversee the systematic progression of food substances through the gastrointestinal tract. 

In the case of IBS, the brain-gut axis may malfunction due to the dysfunction of the neurotransmitters that relay signals from the brain to the gut or vice versa, which would, in turn, cause a disruption in gut homeostasis (stability). 

This then led to the hypothesis that brain-gut axis dysfunction may affect bowel movements, resulting in IBS symptoms.

Risk factors for IBS

Some factors can increase the risk of developing IBS, such as:

1. Stressful early life experiences

Certain early life experiences or stressful events, such as childhood trauma and physical and sexual abuse, may contribute to the development of IBS in certain individuals.

2. Mental disorders

Various research studies have shown that certain mental conditions, such as anxiety, somatic symptom disorder, post-traumatic stress disorder, and depression, may contribute to increasing an individual's chances of developing IBS.

3. Bacterial infections

Bacterial infections in the digestive tract may contribute to the development of IBS. The small intestine is likely to experience bacterial overgrowth or a change in the amount of bacteria in some people, resulting in the development of IBS symptoms.

4. Food intolerance and sensitivity

For some individuals, the presence of certain food substances in the digestive tract can cause food intolerance or allergic reactions in the gut, thus resulting in hypersensitivity and irritation of nerves in the gastrointestinal tract.  

5. Age

Research conducted on individuals between the ages of 40 and 60 suggests that individuals younger than the age of 60 may have a higher chance of showing symptoms of IBS.

However, this doesn’t mean people older than 60 cannot receive a diagnosis of IBS. People of all ages can develop IBS, especially those assigned female at birth.

7. Unhealthy diet

A 2022 research study conducted on secondary school girls proved that excessive consumption of an unhealthy diet, which mainly involved a high intake of soft drinks and low or inadequate fruit and vegetable consumption, was a risk factor for IBS.

Clear indications as to why this happens weren't noted in the study; however, the research proved that greater numbers of students who presented with IBS symptoms weren't eating healthy meals.

8. Chronic diseases

According to a recent research study, people who've recovered from chronic diseases such as diabetes and hypertension, as well as patients who were infected with COVID-19 within a year, may run a higher risk of developing irritable bowel syndrome than people who haven't had any of the previously mentioned health issues.

9. Family history of IBS

Results from a recent study published in Health Science Reports suggested that individuals with a first-degree relative, such as a parent or sibling, who had IBS may run a risk of developing the syndrome as well.

The study went ahead to point out an association between some variations in the sucrase-isomerase gene and an increased risk of IBS. Put simply, individuals with a family history of this genetic variation may have a higher risk of having IBS.

IBS complications

IBS doesn’t always cause complications, especially when managed. But in some cases, it may cause complications, like: [13] [14

Signs and symptoms of IBS

Individuals with IBS would likely experience symptoms like:  

  • Diarrhea and constipation
  • Excessive and uncomfortable bowel movements
  • Inability to control when you defecate (bowel incontinence) 
  • Abdominal pain and cramping
  • Bloating 
  • Excess gas (flatulence) 
  • Constant urge to urinate (polyuria)
  • Presence of mucus in stool 

Other less common symptoms of IBS include:

Is IBS a genetic disorder?

Although the precise cause of IBS is not clear, studies have shown that relatives of individuals with IBS are two or three times more likely to have IBS, irrespective of age or gender. The genetic estimate range is said to be from 1-20%, while the hereditary range is from 0–57%.

This means that IBS development may also be linked to genes, and individuals with a family history of IBS may be more likely to develop the syndrome.

Is IBS a risk factor for colon cancer?

IBS is not considered a risk factor for colon cancer. Results from a 2022 research study indicate that people with IBS may not have a long-term risk of colon cancer, as the risk of colon cancer was not increased in the study participants who had been diagnosed with IBS for more than one year.

However, the study showed that the risk of colon cancer seemed to be higher in people who were still in their first year of IBS diagnosis. The study further explained that this does not demonstrate that IBS increases the risk for colon cancer; rather, it may mean that overlapping IBS and colon cancer symptoms may have caused a misinterpretation of colon cancer as IBS.

Also, IBS usually doesn’t have inflammatory effects on the gastrointestinal tract, which means there is less chance of it resulting in cancer. Hence, there is no concrete scientific evidence that IBS is a disease precursor to cancer.

However, if you suspect that you may be suffering from colon cancer and/or IBS, do well to seek professional help from your doctor.

When to speak with a doctor about IBS concerns

If you suspect that you have IBS or are persistently experiencing some of the signs and symptoms of IBS, such as bowel incontinence, bloating, diarrhea and constipation, cramping, and abdominal pain, it's important that you visit your doctor or gastroenterologist for examination. 

There are available management therapies for IBS. So, it's important that you seek immediate professional help. They will properly examine and diagnose you using the ROME IV criteria (a medical outline used in diagnosing IBS) to ascertain what form of IBS you might have through your symptoms, such as IBS with constipation (IBS‐C), IBS with diarrhea (IBS‐D), or IBS with both (IBS‐M).

They will also go ahead and place you on the right medicinal and non-pharmaceutical treatments to help relieve your discomfort. 


  1. Nicholas Patel et al. (2022). Irritable Bowel Syndrome
  2. Ahmad Y. Arnaout et al. (2023). The Prevalence and Risk Factors of Irritable Bowel Syndrome (PRIBS study) Among Adults in Low‐ and Middle‐income Countries: A Multicenter Cross‐sectional Study.
  3. National Institute of Health. (2017). Symptoms & Causes of Irritable Bowel Syndrome
  4. Mónica Gros et al. (2021). Neurotransmitter Dysfunction in Irritable Bowel Syndrome: Emerging Approaches for Management
  5. Su Yuon Nam et al. (2010). Prevalence and Risk Factors of Irritable Bowel Syndrome in Healthy Screenee Undergoing Colonoscopy and Laboratory Tests.
  6. Heidi M. Staudacher et al. (2023). Irritable bowel syndrome and mental health comorbidity — approach to multidisciplinary management
  7. Mihaela Fadgyas-Stanculete et al. (2014). The relationship between irritable bowel syndrome and psychiatric disorders: from molecular changes to clinical manifestations. 
  8. Uday C. Ghoshal et al. (2017). Small Intestinal Bacterial Overgrowth and Irritable Bowel Syndrome: A Bridge between Functional Organic Dichotomy
  9. Sheila E. Crowe. (2019). Food Allergy Vs Food Intolerance in Patients With Irritable Bowel Syndrome
  10. Rok Son Choung et al. (2006). Food Allergy and Intolerance in IBS
  11. Abraham B. Beckers et al. (2021).Age-Related Decrease in Abdominal Pain and Associated Structural- and Functional Mechanisms: An Exploratory Study in Healthy Individuals and Irritable Bowel Syndrome Patients. 
  12. Wjdan Alharbi et al. (2022). Prevalence and Associated Risk Factors of Irritable Bowel Syndrome Among Female Secondary School students in Ar Rass City, Qassim Region
  13. Cedars-Sinai. (2022). Irritable Bowel Syndrome (IBS)
  14. Sarah Ballou et al. (2019). Effects of Irritable Bowel Syndrome on Daily Activities Vary Among Subtypes Based on Results From the IBS in America Survey.
  15. National Health Service (2021). What is IBS? 
  16. National Health Service (2023). Irritable bowel syndrome (IBS).
  17. Yuri A. Saito (2012). The Role of Genetics in IBS.
  18. Xinhui Wu et al. (2022). Risk of Colorectal Cancer in Patients With Irritable Bowel Syndrome: A Meta-Analysis of Population-Based Observational Studies
  19. M Nørgaard et al. (2011). Irritable bowel syndrome and risk of colorectal cancer: a Danish nationwide cohort study