The Risks of Untreated Ulcerative Colitis

Treating ulcerative colitis is important to prevent complications

Ulcerative colitis is a chronic illness that is a type of inflammatory bowel disease (IBD). Ulcerative colitis is usually characterized as causing inflammation in the lining of the colon, but it is an immune-mediated condition. This means that it involves the body’s immune system, which can lead to effects in organs and body systems other than the digestive tract.

A diagnosis of ulcerative colitis is difficult to receive for many reasons. Often people have not even heard of the disease before their diagnosis. Learning that it will probably mean taking medication for the rest of their lives can be upsetting and daunting.

In addition, ulcerative colitis goes through periods of active disease and less active or no activity (sometimes called remission). Little is currently known about why ulcerative colitis might flare-up, though some people living with the disease are able to identify their personal triggers.


What Causes Ulcerative Colitis?

Why Ulcerative Colitis Needs Treatment

Ulcerative colitis needs ongoing treatment, and the options available will vary depending on a number of factors, including if the disease is considered mild, moderate, or severe.

In many cases, the disease will respond to treatment but it may take some trial and error, as well as time, to find the right regimen. People with ulcerative colitis will use a variety of methods to keep the disease under control including medication, diet, supplements, and lifestyle modifications.

However, it’s now known that while keeping symptoms at bay is important for quality of life, there can be inflammation in the colon even though someone with ulcerative colitis feels “well.” Having inflammation, even if it causes few or no symptoms, has effects on the body that can be far-reaching.

For this reason, gastroenterologists who treat IBD are becoming increasingly focused on working to calm that inflammation. Without treatment, the inflammation from ulcerative colitis can lead to complications.

In some cases, especially when feeling better, people living with ulcerative colitis may consider stopping treatment. This is a decision that should be made while working closely with a gastroenterologist. Stopping treatment without discussing it first can have unintended consequences that go beyond the disease coming back. In addition, if there is inflammation that is not being managed, it could lead to consequences.

ulcerative colitis diagnosis
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Continuous Signs and Symptoms

Ulcerative colitis can cause signs and symptoms such as diarrhea, blood in the stool, nausea, fatigue, and abdominal pain. One of the goals of treatment is to stay on top of the inflammation that may contribute to these symptoms.

The symptoms of ulcerative colitis can lower a person’s quality of life significantly, as well as affect personal relationships and the ability to have a rewarding and successful career. While it does take time and effort to develop a treatment plan, the result can be the cessation of the symptoms and an improvement in quality of life.

Colon Cancer

A chief worry of some people living with ulcerative colitis is the risk of developing colon cancer. It is a valid concern because the risk of colon cancer is higher in people who are diagnosed with ulcerative colitis than it is in people who do not live with the disease.

It’s important to note that more than 90% of people diagnosed with IBD will never develop colon cancer. However, there is a risk that is mainly affected by two factors: the length of time since diagnosis and how much of the large intestine is affected by the disease. Other risk factors include if a patient also has a liver disease associated with ulcerative colitis called primary sclerosing cholangitis and if there is a family history of colorectal cancer.

After eight to 10 years of having ulcerative colitis, the risk of colon cancer starts to increase. It’s thought that having continuous inflammation can lead to changes in the cells of the large intestine, which may have the further effect of causing cells becoming cancerous.

Those who have disease only in the rectum (the last part of the large intestine) have the lowest amount of risk. Disease in only part of the large intestine carries an intermediate amount of risk; the greatest risk comes when the entire colon is affected by the disease (known as pan-colitis).

The results of different studies vary, but in general, the risk of colon cancer for people with IBD starts to increase by 0.5% to 1% every year about eight to 10 years after diagnosis.

Some studies have also shown that people with IBD may be as much as five times more likely to develop colon cancer than those who do not have IBD.

For these reasons, continuing treatment for ulcerative colitis is important, as is regular screening for colorectal cancer. After eight to 10 years of having ulcerative colitis, a yearly colonoscopy might be recommended to check for polyps or colon cancer.


Arthritis is the most common extra-intestinal side effect of IBD. One of several different forms of arthritis may affect as many as 25% of those diagnosed with IBD. In some cases it may not be possible to avoid the development of arthritis and treating the IBD may not help with symptoms. However, there is one form, called peripheral arthritis, that may improve when the IBD is well-controlled.

Peripheral arthritis may cause pain, swelling, and stiffness in joints that may migrate between joints. Some of the medications used to treat IBD may have the added benefit of treating peripheral arthritis as well.


One of the hallmark symptoms of ulcerative colitis is blood in the stool. In severe cases, there may be a significant amount of bleeding. The body can’t replace this blood as fast as it is being lost. This results in anemia, which can cause fatigue, weakness, chest pain, shortness of breath, and dizziness.

In severe cases of ulcerative colitis, losing too much blood can be life-threatening. For this reason, it’s important to treat the inflammation and ulcers in the colon and prevent them from causing bleeding.

Bone Loss

People with ulcerative colitis may develop vitamin deficiencies, including a vitamin D deficiency. Vitamin D is the "helper" vitamin for calcium, and an appropriate amount of calcium is needed to keep bones healthy. For this reason, some people with IBD may be recommended vitamin D supplements by their healthcare team.

Severe bone loss can cause osteoporosis, and the risk is increased for people assigned female at birth and those who are lower weight. Untreated IBD may complicate nutrition, which is one more reason to keep the ulcerative colitis well-managed.

Bowel Perforation

A perforation (hole) in the bowel is rare with ulcerative colitis. It is more common during the first flare-up of the disease and in those who have extensive disease that has caused the intestinal walls to become thinner.

Keeping ulcerative colitis controlled can help prevent the disease from becoming severe enough to affect the walls of the intestine so significantly. A perforation in the colon may be treated by either repairing the hole or removing a section of the colon (which is called a resection). 

Mouth Ulcers (Aphthous Stomatitis)

Ulcers in the mouth can sometimes occur with a flare-up of IBD. They usually are not considered serious, but they can be painful, difficult to treat, and lead to a decrease in quality of life.

In many cases, mouth ulcers will start to form during a flare-up and, for some people, may be one of the first signs that inflammation is starting again. The ulcers may start to get better when the ulcerative colitis is better controlled.

A Word From Verywell

There could be other complications from undertreated ulcerative colitis that are not listed here. IBD is a complex condition, and there are still many unknowns as far as what causes the disease and why it is associated with so many extra-intestinal manifestations.

Unfortunately, some people with IBD have disease that is not well-managed. There are a number of reasons for this, some of which are out of the control of the patient. Being well-informed about ulcerative colitis and how it can lead to serious complications is important, and this information is not something that is always communicated to patients.

The best way to avoid ulcerative colitis from causing complications is to treat the disease effectively. That does mean working with a gastroenterologist and, usually, taking medication(s). Stopping medications suddenly, even when feeling better, is not typically recommended. There are situations when this might be appropriate, such as after achieving a deep state of remission, but this must be weighed against the risk of the disease returning and causing more flare-ups. 

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.

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.