Risks of Untreated Crohn's Disease

Inflammation from Crohn's disease could lead to complications

Crohn’s disease is a chronic, immune-mediated condition that is one form of inflammatory bowel disease (IBD). Other forms of IBD include ulcerative colitis and indeterminate colitis. Crohn’s disease can affect the entire body in different ways because it affects the immune system. However, the disease is usually characterized as one that primarily affects the digestive system. Crohn’s disease can cause inflammation in any part of the digestive tract, from the mouth to the anus. Even though Crohn’s disease is partly genetic, for many who are diagnosed, there is no family history of IBD, and they may have never heard of the disorder before.

Crohn’s disease can not be cured, which means that treatment is needed for the rest of one’s life after diagnosis. This treatment can take many forms, but the main focus is often to keep the inflammation caused by the disease under control. Crohn’s disease goes through periods of being more (called flare-ups) and less active (called remission), and while some people who live with the disease may learn what triggers symptoms, for others, there may not always be a clear-cut reason that symptoms pick up again.

risks of untreated crohn's disease
Laura Porter / Verywell

Why Crohn’s Disease Needs Treatment

Treatment options for Crohn’s disease can include a variety of options, such as medication, lifestyle changes, alternative and complementary therapies, and surgery. It is necessary to treat active Crohn’s disease because the condition not only causes ulcers in the digestive tract but is also associated with problems in the eyes, skin, joints, and other organ systems in the body.

Untreated Crohn’s disease could result in inflammation that affects the digestive system and other body systems.

For those who are able to cope with the signs and symptoms of the disease, the inflammation that the disease causes in the intestines may not seem like a reason to be concerned. However, inflammation in the body that is not stopped could cause a variety of serious health problems. Some of these complications may take some time to show up or to cause symptoms themselves.

When the Crohn’s disease is not active, it may be considered to be in remission. However, there are several different forms of remission. One type is called clinical remission and it means that the signs and symptoms of the disease are not active and that a person feels better than they did before.

Feeling better is important for your quality of life and it’s what some people may focus on for their treatment decisions, but it is possible that inflammation could still be going on even when feeling relatively well. This is why IBD specialists are increasingly focused on making sure that not only do patients feel good and get back to their regular activities, but also that the inflammation in the body is stopped and that the ulcers in the intestines are healed. This is referred to as "endoscopic remission."

Ongoing Signs and Symptoms

Some of the signs and symptoms of Crohn’s disease include abdominal pain, diarrhea, bloody stools, vomiting, nausea, and fatigue. Inflammation in the digestive tract may lead to these symptoms and others, which is why is needed.

Many people with Crohn’s disease find that the symptoms limit their ability to go about their daily activities like work or school and socializing. Some people may find that they can’t get very far from a bathroom or even leave the house.

Creating a treatment plan that addresses the underlying inflammation and may, therefore, reduce or eliminate some of these symptoms may help in getting back to a better quality of life.


People with Crohn’s disease are at an increased risk of developing an abscess. An abscess is a collection of pus that is located beneath the skin. Symptoms of an abscess can include a painful lump, fever, nausea, and warmth or tenderness in the skin over the abscess.

People with Crohn’s disease may be more prone to develop an abscess that is in the abdominal area or in the perianal area (in or around the anus). In some cases a perianal abscess may occur if there is a tear in the skin in the anus and then some bacteria gets inside the tear.

The treatment for an abscess will depend on where it is located, how large it is, and if it is causing other complications. In some cases, surgery may be needed to clear out an abscess so that it may heal. In others, a drain may need to be put in to allow the fluid to drain out of the abscess. Untreated Crohn’s disease that is causing inflammation may lead to an increased risk of a complication such an abscess. 

Bowel Obstructions

Crohn’s disease is associated with blockages in the intestine. A blockage is when the small or the large intestine becomes partially or totally blocked and undigested food is unable to pass through it. Some of the symptoms of an obstruction include fever, abdominal distention, vomiting, constipation and/or diarrhea, and abdominal pain (sometimes severe).

Untreated Crohn’s disease could lead to obstructions because the ongoing inflammation could cause the intestine to thicken or it could cause narrowing of the intestine (which are called strictures). Abdominal surgery (such as that which is done to treat IBD) could also lead to the development of adhesions, and this could also cause the intestine to become too narrow.

Bowel obstructions can be serious so a suspected blockage is a reason to seek medical treatment right away. In some cases, the obstruction might clear with the use of a stool softening medication that helps to move stool along. Another treatment that might be used in the hospital is called decompression, where a nasogastric (NG) tube is passed through the nose and down through the esophagus and into the stomach.

If the obstruction can’t be cleared in these ways or if it has lead to another complication such as a hole (perforation) in the intestine, surgery may be the next step. The obstructed area of the intestine might be removed or adhesions or a stricture may be removed or opened up. In certain cases, laparoscopic surgery, which is less invasive, may be used for these procedures.

Colon Cancer

People who have Crohn’s disease that affects the colon (which is a type that’s called Crohn’s colitis) are at increased risk of developing colon cancer. This risk is greater after having the disease for 8 to 10 years , and one meta-analysis put the risk as being 2.9% at 10 years, 5.6% at 20 years, and 8.3% at 30 years after diagnosis .

Regular screening for colon cancer is recommended and how often it is needed (usually with a colonoscopy) should be discussed with a gastroenterologist. In some cases having a yearly colonoscopy might be recommended.

Having constant inflammation from Crohn’s disease is thought to cause the cells in the colon to change and have the potential to become cancerous. It’s worth noting that about 90% of people with IBD will not develop colon cancer. 


A fistula is an abnormal connection between two structures in the body. Crohn’s disease is associated with an increased risk of the development of fistulas . A fistula can form between, for instance, one part of the bowel and another part of the bowel. They can also form between the bowel and the skin or the bowel and the vagina. Some of the symptoms of a fistula can include pain or tenderness in the area, fever, itching, and feeling generally unwell.

Treatment for a fistula will depend on where it is located. conservative treatments are often tried first. In some cases, surgery might be needed and there are several different types of fistula surgery that might be done. In other cases, fistulas may become difficult to heal and become chronic. 

Malnutrition and Vitamin Deficiencies

Crohn’s disease can affect the small intestine, which is where most vitamins and minerals are absorbed. If the small intestine is inflamed, it is less able to absorb nutrients from food.

Different sections of the small intestine are responsible for absorbing different nutrients. Therefore, knowing where the inflammation is concentrated can help in understanding which vitamins and minerals might be lacking and if there’s a need for supplementation. For instance, inflammation in the last section of the small intestine, the ileum, could lead to a lowered uptake of vitamin B12. A low level of B12 might cause signs and symptoms ranging from fatigue to the development of anemia to a feeling of tingling in the extremities.

Other vitamin and mineral deficiencies could lead to a wide range of health problems. A lack of calcium, iron, vitamin A, vitamin D, vitamin K, and zinc are some of the other more common deficiencies in people who have Crohn’s disease .

A calcium deficiency may put people at the risk for bone loss. Vitamin D is the helper vitamin for calcium, and the lack of this vitamin that is often observed in people who live with IBD may further complicate the problem of bone loss. Severe bone loss can result in the development of long-term issues such as osteopenia and osteoporosis.

People with Crohn's disease who have concerns about vitamin and mineral deficiencies should speak to their healthcare team about the need for any supplementation.


The bowel is similar to a garden hose, in that there is a space inside for food and waste material to move through it. When a section of the inside of the bowel becomes narrowed, it is called a stricture. People with Crohn’s disease are at an increased risk of developing strictures .

A stricture may cause pain and it can also contribute to the development of bowel obstructions if food is not able to pass through the narrowed area. Strictures might go undiagnosed because they might not cause any signs or symptoms.

People who have strictures might need to alter their diet in order to lower the risk of obstructions. Foods that are fibrous such as popcorn, nuts, or raw vegetables might need to be avoided on the advice of a gastroenterologist or a dietician.

In some cases, strictures might need surgery to either open up the area (which is called a strictureplasty) or to remove the part of the intestine that is affected (called a resection).


Crohn’s disease may cause ulcers to form in the digestive tract . These ulcers can become deep and go through several layers of the intestinal wall. Deep ulcers are more challenging to heal and could lead to complications. They may also cause the abdominal pain that is one of the symptoms of Crohn’s disease, which can be chronic and in some cases, severe.

One complication that can happen is called a perforation, which is a hole in the intestine. A bowel perforation is not common, but it is an emergency and is most often treated with surgery. Symptoms of a bowel perforation may include fever, chills, severe abdominal pain, nausea, vomiting, and rectal bleeding.

Ulcers can appear throughout the digestive tract with Crohn’s disease, including in the mouth (which is called aphthous stomatitis). These are usually not considered serious but they can be painful and make it uncomfortable to drink, eat, or talk. Treatments can include changing the diet and topical anesthetics for the discomfort. Most of the time mouth ulcers get better when the Crohn’s disease is more controlled.

A Word From Verywell

Crohn’s disease is a lifelong, chronic condition, and there is currently no cure. There are, however, several treatments that can help reduce inflammation and put the disease into remission. For some people, remission can wind up being quite durable and last for a long period of time.

When Crohn’s disease isn’t controlled, it can lead to a host of other problems and affect the whole body, not just the digestive tract. For this reason, it is important to work closely with physicians, and especially a gastroenterologist, to find a treatment that reduces inflammation.

Feeling better is important, especially when the symptoms prevent living a full life, but the lack of symptoms doesn’t always mean that there is no inflammation in the digestive tract. When the inflammation is allowed to continue untreated in the digestive tract it can cause long-term issues, some of which may not be easy to treat or be irreversible. Seeing a gastroenterologist on a regular basis and tracking inflammation through tests like colonoscopy, blood tests, and fecal calprotectin is important so you can be healthy as possible while living with Crohn’s disease. 

7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Amber J. Tresca
Amber J. Tresca is a freelance writer and speaker who covers digestive conditions, including IBD. She was diagnosed with ulcerative colitis at age 16.