Ulcerative colitis (UC) is a type of inflammatory bowel disease (IBD). It happens when the immune system attacks food, bacteria, and other substances in the large intestine (colon). This attack causes inflammation that can permanently damage the colon lining.

Periods of UC symptoms are called flare-ups. Symptom-free periods are called remissions. People with UC alternate between flare-ups and remissions.

Taking medications can help control the immune response and bring down inflammation in your colon before it causes damage and complications. Some people may need surgery to remove damaged parts of their colon.

Read on to learn about six long-term complications of uncontrolled UC.

Severe bleeding

Damage to the colon can cause bleeding. You may notice the blood in your bowel movements. Bloody stools are the main symptom of UC.

The bleeding can be severe enough to cause anemia — a drop in red blood cells that carry oxygen throughout your body. It causes symptoms like fatigue and shortness of breath.

Swollen colon (toxic megacolon)

Toxic megacolon is a rare but dangerous complication of UC. It happens when gas becomes trapped in the colon and makes it swell up.

The colon can become so enlarged that it breaks open and releases bacteria into the blood. The bacteria can cause a deadly blood infection called septicemia.

Symptoms of toxic megacolon include:

  • belly pain and swelling
  • fever
  • fast heart rate

Doctors treat toxic megacolon with medications to bring down swelling and prevent infection. If treatments don’t work, you may need surgery to remove part or all of your colon.

A hole in your intestine

Inflammation and sores can weaken the colon wall so much that it eventually develops a hole. This is called a perforated colon.

A perforated colon usually happens because of toxic megacolon. It’s a medical emergency.

Bacteria that live in your intestine can get out through the hole into the abdomen. These bacteria can cause a serious infection called peritonitis. If this happens, you’ll need surgery to close the hole.

Increased risk for colorectal cancer

Constant inflammation in the intestine can eventually make cells turn cancerous. People with UC are about twice as likely to get colorectal cancer as people without the disease.

Overall, the risk is low, and most people with UC will never get colorectal cancer. But your likelihood of getting cancer increases after you’ve had the disease for eight to 10 years.

You’re more likely to get colorectal cancer if you have:

  • severe inflammation in your colon
  • a family history of colorectal cancer

It’s important for people who’ve had UC for more than eight years to get screened every one to two years with a colonoscopy. This test uses a long flexible tube to find and remove abnormal tissue in your lower intestine.

Bone loss (osteoporosis)

UC increases your risk of the bone-weakening disease osteoporosis. Up to 60 percent of people with this disease have thinner than normal bones.

Severe inflammation in your colon or having part of your colon removed with surgery can make it harder for your body to absorb calcium and vitamin D. You need these nutrients to keep your bones strong. Inflammation can also disrupt the process your body uses to rebuild new bone.

Taking corticosteroids can also contribute to osteoporosis. These medications reduce inflammation in the colon, but they also weaken bones.

Having weak bones increases your risk of fractures. Eating a diet rich in calcium and vitamin D can help protect your bones. Doing weight-bearing exercises like walking up stairs and dancing also strengthens bones.

If a bone density test shows that you have weakened bones, your doctor can prescribe bisphosphonates or other medications to protect them. You may also need to reduce your use of steroids.

Primary sclerosing cholangitis (PSC)

Primary sclerosing cholangitis (PSC) is inflammation and scarring in the bile ducts. These tubes carry the digestive fluid bile from your liver to your small intestine. PSC is common in people with UC.

Scars can make the bile ducts narrow. The narrowing causes bile to back up in the liver. Over time, the liver can become scarred and damaged enough to need a transplant.

The takeaway

UC symptoms come and go, but the disease is chronic. To lower your risk for complications, follow the treatment your doctor prescribed. Also, talk to your doctor about lifestyle changes to help you manage your condition.