Causes of Crohn’s Disease

Inflammatory Bowel Disease; the name may sound a bit funny yet scary at the same time. The term is primarily used to describe two ailments- Ulcerative Colitis & Crohn’s Disease, which affect nearly 2 million people in the U.S. and about 3.2 million in Europe.The two illnesses affect different parts of the digestive tract. 

The digestive tract, which runs from the mouth to the anus, has two major components in the form of the small intestine (which is about 10-16 feet in length) and the large intestine (a.k.a. colon -  about 5 feet long). Ulcerative colitis, as the name might suggest, impacts the colon, and entails the formation of ulcers in the area. On the contrary, Crohn’s Disease, which was named after its discoverer Burrill B. Crohn [an American Gastroenterologist who discovered the disease in 1932] can influence any part of the digestive or gastrointestinal tract.2 

Even though they both sound like interesting diseases to learn more about, for today's article we will dive into Crohn’s Disease and its mechanisms, symptoms and causes.

What is Crohn’s Disease?

Essentially, the disease involves the chronic inflammation of the gastrointestinal tract (GI)  and can affect individuals of any age but is usually initially seen in adolescents and adults aged between 20 and 30.3 As mentioned before, Crohn’s can cause inflammation in any part of the GI tract but is mostly seen to affect the small intestine (also known as ileum) and the beginning of the large intestine.4 Sometimes these inflammations can occur in patches (normal intestine in between diseased areas). The disease can affect people from any ethnic background though it is commonly found in Caucasians and recently there has been a growing incidence of cases among Hispanics and Asians.3

How is it Diagnosed?

Diagnosis of Crohn’s disease involves a physical exam and diagnostic tests. The physical exam involves feeling the abdomen for bloating, listening to abdominal sounds using a stethoscope, checking the abdominal area for pain and examining if the liver and spleen are swollen. Diagnostic tests include lab work, endoscopy of the intestines and CT scans.5


There are many symptoms that an individual with Crohn’s disease may experience and these include:5

  • Diarrhoea
  • Stomach ache or cramping in the abdominal area
  • Bloody stool
  • Fatigue
  • Unintentional weight loss
  • Fever
  • Joint pain
  • Redness in the eyes
  • Painful and red skin patches and/or bumps

Causes of Crohn’s Disease

If you have reached this far in the article, you must definitely be interested in finding out the root causes behind a disease like this. While the exact cause is unknown, it is thought to be a combination of genetic predisposition and autoimmune issues.

Below we will see how these factors lead to symptoms of Crohn’s Disease

Overactive Immune Response

An autoimmune reaction occurs when the body’s own immune system cells begin attacking the healthy cells, and in the case of Crohn’s, this is primarily thought to be stimulated by bacteria in the gut.6 As recently as February 2021, scientists have discovered that in patients with Crohn’s disease, there is an excess of a bacterial species called enteroinvasive Escherichia coli (AIEC), which stimulates inflammation in the intestine by producing a substance that reacts with the immune system cells of the intestine. Researchers further found that hindering the production of this substance in mice (affected with Crohn’s Disease) resulted in relief of symptoms and reduction in gut inflammation.7 Constant inflammation of the digestive tract can lead to presenting symptoms.

Genetic Causes

While a clear genetic link has not been established, there does appear to be a risk of inheriting Crohn’s disease, especially among those who come from Jewish lineage. The National Human Genome Research Institute states that children with one parent affected with the disease have a 7 -9% risk of developing Crohn’s and a 10% chance of having some form of Inflammatory Bowel Disease, in their lifetime. If both parents are affected, the chances of getting impacted with Crohn’s increases to a concerning 35%.8

Other Causes

a. Smoking:  As you might be knowing, smoking can cause a plethora of issues ranging from cardiovascular to respiratory. So, it might not be surprising to add that smoking can not only enhance the risk of developing Crohn’s disease but also exacerbate its course which would lead to an increased need for treatments such as steroids, immunosuppressants and surgeries.10

b. Medication: While there is no conclusive evidence, there may be a link between NSAIDs (also known as Non-Steroidal Anti-Inflammatory Drugs), which include medicines such as Aspirin or Ibuprofen, and Crohn’s disease.11 This also applies to antibiotics and birth control pills.

Discovery of an Interesting Treatment 

Before you finish reading the article, I would like to leave you with some interesting information recently discovered. In a study conducted by Case Western Reserve University School of Medicine, researchers discovered that mice, who were placed on a diet of plants with healthy fats such as coconut oil and cocoa butter, were found to have 30% fewer forms of bacteria in their gut. 

This led the first author of the study and Assistant Professor of Medicine at CWRU, Alexander Rodriguez-Palacios, to assert that switching from unhealthy fats to healthy fats in their diet could potentially help patients with Crohn’s disease. The finding therefore not only outlines the benefits of healthy fats in patients with the disease but also underlines the need to maintain a good and healthy diet in our day-to-day lives.12


In summary, Crohn’s disease is a type of Inflammatory Bowel Disease that affects a noticeable percentage of the population around the world, impacting mainly the small intestine. It has a range of symptoms and if you are facing any of them, it would be best to get in touch with your healthcare provider. Crohn’s can have many causes ranging from autoimmune to genetic predisposition and even some uncommon ones such as smoking. Some medications and diets may also have a negative effect on those suffering from Crohn’s. 


  1. Ananthakrishnan AN, Kaplan GG, Ng SC. Changing Global Epidemiology of Inflammatory Bowel Diseases: Sustaining Health Care Delivery Into the 21st Century. Clinical Gastroenterology and Hepatology. 2020 May;18(6):1252–60.
  2. he names: Ulcerative colitis – Crohn’s disease | UNC Multidisciplinary Center for IBD [Internet]. [cited 2022 Sep 2]. Available from:
  3. Overview of crohn’s disease [Internet]. Crohn’s & Colitis Foundation. [cited 2022 Oct 4]. Available from:
  4. National Institute of Diabetes and Digestive and Kidney Diseases. Definition & Facts for Crohn’s Disease | NIDDK [Internet]. National Institute of Diabetes and Digestive and Kidney Diseases. 2019. Available from:
  5. Diagnosis of Crohn’s Disease | NIDDK [Internet]. National Institute of Diabetes and Digestive and Kidney Diseases. 2019. Available from:
  6. Crohn’s disease – Symptoms – NHS [Internet]. 2017 [cited 2022 Oct 4]. Available from:
  7. Symptoms & causes of crohn’s disease | niddk [Internet]. National Institute of Diabetes and Digestive and Kidney Diseases. [cited 2022 Oct 4]. Available from:
  8. Study Identifies “Achilles heel” of Bacteria Linked to Crohn’s Disease [Internet]. WCM Newsroom. Weill Cornell Medicine; 2021 [cited 2022 Sep 2]. Available from:
  9. About Crohn’s Disease [Internet]. 2011. Available from:
  10. Lakatos PL, Szamosi T, Lakatos L. Smoking in inflammatory bowel diseases: Good, bad or ugly? World Journal of Gastroenterology [Internet]. 2007 [cited 2019 Dec 20];13(46):6134. Available from:
  11. Moninuola OO, Milligan W, Lochhead P, Khalili H. Systematic review with meta-analysis: association between acetaminophen and nonsteroidal anti-inflammatory drugs (NSAIDs) and risk of Crohn’s disease and ulcerative colitis exacerbation. Alimentary Pharmacology & Therapeutics. 2018 Apr 5;47(11):1428–39.
  12. High Fat Diet Reduces Gut Bacteria, Crohn’s Disease Symptoms [Internet]. School of Medicine | School of Medicine | Case Western Reserve University. 2018 [cited 2022 Sep 2]. Available from: disease-symptoms

Punyaslok Mishra Mishra

MB BCh BAO - Queen's University Belfast, Northern Ireland

Punyaslok is an emerging medical professional from Queen's University Belfast with a specialization in Medicine. He has showcased leadership as the President of the Asian Medical Students’ Association in Northern Ireland since August 2022. Besides, he contributes as a Peer Mentor and has recently undertaken a vital role as a Medical Writer Intern at Klarity, where he pens insightful articles for a health library, discussing topics from angina to the enzymes in papaya. Notably, Punyaslok's research on the potential of Mesenchymal Stem Cells in treating Anthracycline Induced Cardiomyopathy is affiliated with Queen's University, signifying his deep interest in advancing therapeutic measures in the medical realm. presents all health information in line with our terms and conditions. It is essential to understand that the medical information available on our platform is not intended to substitute the relationship between a patient and their physician or doctor, as well as any medical guidance they offer. Always consult with a healthcare professional before making any decisions based on the information found on our website.
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