Inflammatory Bowel Disease (IBD): Causes, Symptoms, and Long-Term Effects

An overview of inflammatory bowel disease (IBD), covering known causes, risk factors, symptoms, long-term complications, and current treatment options for its two main types: ulcerative colitis and Crohn’s disease. It also highlights Teva's research on IBD, focusing on both the inflammatory and scarring (fibrotic) aspects of these conditions.

Teva’s commitment to innovative medicines

In inflammatory bowel disease (IBD), both inflammation and long‑term scarring present ongoing scientific challenges.

Teva is researching a potential new treatment for IBD. This investigational medicine is designed to target a specific pathway in the immune system, TL1A, which may play a role in IBD inflammation. We are doing this work in collaboration with Sanofi.

Together, we are studying IBD in a broader sense, focusing on both the ongoing inflammation and the long-term scarring (fibrosis) that can develop with IBD. By leveraging our combined R&D expertise, we aim to help develop future treatments for people living with ulcerative colitis and Crohn’s disease.

IBD key facts

• IBD includes ulcerative colitis (UC) and Crohn’s disease (CD), which affect the digestive system in different ways.
• UC affects the colon, while CD can occur anywhere along the digestive tract.
• Almost 5 million people worldwide live with IBD.
• The exact cause of IBD is unknown, but genetics, environment, and the microbiome may all contribute.
• IBD symptoms include diarrhea, abdominal pain, rectal bleeding, and fatigue; symptoms often fluctuate between flares and periods of remission.
• Long-term IBD complications can include intestinal fibrosis and strictures, which may require surgical intervention if untreated
• There is currently no cure. Teva is exploring investigational therapies, including approaches focused on the fibrotic components of UC and CD, through partnerships such as the Teva–Sanofi collaboration.

FAQs: Inflammatory Bowel Disease (IBD)

What is IBD?

Inflammatory bowel disease (IBD) is a chronic inflammatory condition that affects the digestive system. IBD primarily refers to two conditions: 01

1. Ulcerative colitis (UC)
2. Crohn’s disease (CD)

IBD vs IBS

With similar acronyms, IBD can sometimes be confused with irritable bowel syndrome (IBS). However, while IBS can share similar symptoms to IBD, such as cramps and diarrhea, IBS does not cause inflammation in the gastrointestinal (GI) tract. 02

What is the difference between ulcerative colitis and Crohn’s disease?

CD and UC both fall under the IBD umbrella. Key differences lie in the location of the disease, whether inflammation is in “patches” or is “continuous,” and in some symptoms. 03

Ulcerative colitis (UC)

• Restricted to the large intestine (colon)
• Inflammation affects the whole colon with no patches
• Inflammation is restricted to the innermost lining of the colon 03

Crohn’s disease (CD)

• It can affect any part of the digestive tract (from the mouth to the anus)
• Inflammation is often in “patches,” with healthy tissue between inflamed areas
• Inflammation can affect all layers of the bowel wall 03

Who is affected by IBD?

About 4.9 million people worldwide live with IBD. 04

Over the past twenty years, diagnoses have increased, and prevalence continues to rise in many regions globally. 05

Sex-based differences in IBD diagnoses

IBD affects both men and women equally, 06 with a majority of people with the condition being diagnosed between the ages of 15 and 30. 07

Research suggests that women in Western countries may have a higher chance of developing CD, as population studies report more females living with a CD diagnosis. [08]

UC diagnoses appear roughly similar among men and women until around age 45. After that age, studies show that more men than women develop UC. 08

Ethnicity and IBD

Historically, Caucasians have had the highest rates of CD/UC. 09

A 2024 study shows these rates have been rising among Black, Hispanic, and Asian populations over the last ten years. South Asian populations have particularly higher rates of this condition. 10

What causes IBD?

The exact causes of IBD (both types) remain unknown. However, research suggests that someone having a combination of risk factors may be more likely to develop IBD. These risk factors are often connected to genetics, environment, and a person’s microbiome. 11 12

Genetics

It’s estimated that between 5% and 20% of people with IBD have a first-degree relative (parents, full siblings) with the same diagnosis. 12

But IBD isn’t caused by a single inherited gene. Although the risk increases when one – or especially both – parents have the condition, it still isn’t guaranteed. 13

Instead, people may inherit a combination of genes that, together, may make the immune system more prone to oversensitivity. 14

Environment

While genes can make a person more susceptible to IBD, it may be the interaction between a person’s environment and their genes that causes the condition. 15

Air pollution, the Western diet, and lack of Vitamin D may contribute to IBD risk in susceptible people. 16

Microbiome

The microbiome refers to the community and balance of bacteria in the gut.

Changes in the microbiome, driven by factors such as diet, illness, and antibiotics, may trigger immune responses that lead to the abnormal inflammation seen in IBD. 16

What are the symptoms of IBD?

Many people with IBD experience periods known as “flares” when their symptoms get worse. These flares can happen unexpectedly. Afterward, the person may experience a period of remission, during which their symptoms are less severe. 17

UC and CD share many symptoms, including prolonged diarrhea and abdominal cramps. 18 However, the two also have some differences. For example, some common symptoms for UC and CD include: 03

UC symptoms

• Urgency to pass stool
• Tenesmus (urgent need to go, even after a bowel movement)
• Diarrhea with blood, mucus, or pus
• Cramps in the lower abdomen
• Fatigue
• Fever
• Joint pain and inflammation

CD symptoms

• Abdominal pain or cramps
• Diarrhea
• Loss of appetite
• Weight loss
• Mouth sores
• Nausea and vomiting
• Anal fistulas (abscesses that drain, leaving an open channel between the bowel and skin)
• Fatigue
• Fever
• Joint pain and inflammation

Differences in UC and CD symptoms

While many UC and CD symptoms overlap, some tend to be more characteristic of one condition than the other. 0319

• Bloody stools are usually more common in UC.
• Weight loss is typically more common in CD.
• Mouth sores and fistulas are normally more common in CD.
• Cramps generally affect the lower middle or left abdomen for UC and the lower right or middle abdomen for CD.

What are the long-term effects of IBD?

IBD can have a debilitating impact across many areas of a person’s well-being. 20 Symptoms may include weight loss, diarrhea, abdominal pain, rectal bleeding, and fatigue, and the condition can affect daily functioning and quality of life. 21

Over time, some people with UC or CD may also experience complications such as intestinal fibrosis and intestinal strictures.

Intestinal fibrosis

Chronic inflammation in the intestines can cause intestinal fibrosis – a buildup of collagen scar tissue in the intestines’ walls.22

Intestinal fibrosis happens because constant inflammation causes the body to go into “healing overdrive.” An excessive buildup of connective tissue in the intestines can lead to blockages known as intestinal strictures. 22

Intestinal strictures

As the intestines narrow from intestinal fibrosis, it may become harder for food and fluids to pass through the GI tract.

Blockages may cause intense cramping and pain, nausea, vomiting, and substantial bloating. If left untreated, intestinal strictures may cause: 23

• Complete bowel obstruction
• Gangrene (tissue death when the intestine’s blood is cut off)
• Perforation of the intestine
• Sepsis (a life-threatening complication of an infection)

Intestinal fibrosis can occur with both CD and UC. Research suggests that intestinal fibrosis is more common in CD and less well established in UC. 24 25

However, both inflammatory and fibrotic disease components may cause long-term difficulties for a person living with IBD.

What is the treatment and management for IBD?

There is currently no cure for IBD. 26 The main goal of treatment is to achieve remission, meaning that inflammation and accompanying symptoms are minimized for as long as possible. 27

Current treatments involve medications, lifestyle changes, and – in the case of severe fibrosis – surgery. Treatment plans vary, and decisions should be made with a healthcare professional.

However, not all treatment options work for everyone, and they may stop being effective over time. 26

Because IBD can be complex and vary from person to person, researchers are exploring new ways to address both inflammation and long-term issues such as fibrosis.

References