Crohn’s disease (CD) is an inflammatory bowel disease that can affect any part of the gastrointestinal tract, but most often affects the end of the small intestine (ileum), the colon, or both.

It’s not known what causes Crohn’s. Among the factors for getting the disease are your immune system, your genes, and your environment.

People with Crohn’s are more susceptible to developing intestinal infections that may lead to complications.

There is no cure for Crohn’s, but remission and management of symptoms is possible with effective treatment. Not treating Crohn’s allows the disease to progress, and serious complications can occur as a result.

To be effective, your Crohn’s treatment should be consistent. If it’s not, complications may arise. So it’s important to stick with a healthy diet and continue taking your medication even when you’re feeling well.

Here are some of the complications associated with untreated Crohn’s disease:

A bowel obstruction occurs when intestinal contents are partially or fully blocked and unable to move. There are several ways that this can occur in people with Crohn’s disease:

  • Inflammation can thicken the intestinal walls enough to narrow or even close off the intestinal tract.
  • Strictures can cause bowel obstructions. A stricture, or stenosis, is an area of the gastrointestinal tract that has been narrowed by scar tissue caused by repeated bouts of inflammation.
  • Adhesions, or strips of fibrous tissue that cause organs and tissues to bind together, can block the intestinal tract.

Ulcers that go completely through the digestive tract wall can create fistulas, which are abnormal connections from the intestines to other body parts.

About 1 in 3 people with Crohn’s disease will likely develop a fistula.

A fistula in the abdomen could cause food to bypass important bowel areas needed for absorption. Fistulas may also develop from the bowel to the bladder, vagina, or skin, draining the bowel contents into these areas.

If left untreated, an infected fistula may form a life threatening abscess.

To prevent a serious infection, fistulas should be treated immediately. The treatment options include surgery, medications, or a combination of the two.

Because of the chronic inflammation due to Crohn’s disease, a section of the intestine can narrow. This may lead to an intestinal blockage that could prevent stool from passing through to your bowel.

An intestinal blockage can cause severe abdominal pain and often requires hospitalization to treat.

Less severe cases often resolve with bowel rest (liquid diet), but medication may be prescribed to help prevent future recurrences.

More serious cases may require surgery. A surgery called a strictureplasty widens the intestine without removing any part of it.

Due to the chronic inflammation of the intestinal tract and abnormal bowel movements, anal fissures aren’t uncommon in those with Crohn’s disease. An anal fissure is a small tear in the opening of the anus.

Among the symptoms of an anal fissure are pain and bleeding during bowel movements.

An anal fissure can reach the internal anal sphincter, the muscle that holds the anus closed. If this occurs, the fissure may not be able to heal.

If an anal fissure doesn’t heal within about 8 weeks, medication or surgery may be required.

Proper nutrition is critical for good health. Your digestive tract is a key site of nutrient absorption. Chronic inflammation in your bowels can interfere with your body’s ability to absorb vitamins and minerals from the foods you eat.

Chronic inflammation caused by Crohn’s disease may also suppress your appetite. This may prevent you from ingesting the nutrients you need to stay healthy.

There are a number of significant issues caused by malnutrition, including anemia caused by a deficiency in iron or vitamin B-12. This is common in people with Crohn’s disease.

Other issues caused by not getting adequate nutrients include:

  • reduced immune system function
  • poor healing
  • generalized fatigue and pain
  • weak muscles and bones
  • decreased coordination
  • kidney malfunction
  • psychological issues like depression

Ulcers, open sores that can appear anywhere along the digestive tract, may occur in people with Crohn’s disease.

These ulcers can be painful and dangerous if they cause internal bleeding. They can also cause perforations, or holes, in the intestinal tract. This may allow digestive contents to enter the abdomen.

If this occurs, immediate medical attention is required.

People with Crohn’s disease have up to a 77% chance of developing osteoporosis, which is low bone density. The risk of bone fractures is at least 40% greater than that of people of the same age and sex without Crohn’s.

Crohn’s-related issues that contribute to weakened bones include:

  • inflammation
  • impaired nutrient absorption
  • physical discomfort that keeps you from being active

Part of your Crohn’s treatment strategy may be to counteract these issues by taking calcium and vitamin D supplements. You should also do regular weight-bearing exercises.

It’s important to have your doctor measure your bone density. This can be done with a painless dual-energy X-ray absorptiometry (DEXA) test.

If you have chronic inflammation of the colon associated with Crohn’s disease, you have a higher risk for colon cancer. The inflammation may result in a constant turnover of the intestinal lining’s cells, increasing the chance for abnormalities and cancer.

The following are some of the colon cancer risk factors for people with Crohn’s disease:

  • an 8- to 10-year history of the disease
  • severe inflammation of the colon
  • a family history of colon cancer
  • a diagnosis of Crohn’s colitis, a condition that only affects the colon

Colon cancer is very treatable if it’s discovered in its early stages. Ask your doctor how often you should get a colonoscopy to check for colon cancer.

The prolonged inflammatory response of Crohn’s disease can trigger a similar reaction in joints and tendons, leading to arthritis.

The most common type of arthritis for people with Crohn’s disease is peripheral arthritis. This causes swelling and pain in the large joints of the arms and legs, such as the knees and elbows.

Peripheral arthritis usually doesn’t permanently damage the joints.

In severe cases, arthritis associated with Crohn’s disease may be treated with anti-inflammatory drugs and corticosteroids.

Nonsteroidal anti-inflammatory drugs (NSAIDs) aren’t generally recommended because they can irritate the intestinal lining, increasing inflammation.

As many as 50 percent of people with Crohn’s disease develop small ulcers in their mouths.

The most common type are minor aphthous ulcers, which look like canker sores and may take about 2 weeks to heal. Less common are major aphthous ulcers, larger sores that can take up to 6 weeks to heal.

In severe cases, your doctor may prescribe immunosuppressive drugs and topical steroids to treat your mouth ulcers.

One of the most common kidney complications associated with Crohn’s disease is kidney stones. They are more common in people with this disease of the small intestine than in people without it, because fat isn’t being absorbed normally.

When fat binds to calcium, a type of salt called oxalate can end up in the kidney, forming stones there. The symptoms of a kidney stone may include pain, nausea and vomiting, and blood in the urine.

The usual treatment for a kidney stone is drinking more fluids and eating a low-oxalate diet that includes plenty of juices and vegetables. If a kidney stone doesn’t pass on its own, it may need to be surgically removed.

Among the other complications associated with Crohn’s disease are eye and skin issues.

Eye pain or itchiness

About 10% of people with an inflammatory bowel disease like Crohn’s disease experience eye problems such as pain and itchiness.

Uveitis, which is a painful inflammation of the eye wall’s middle layer, is one of the most common eye complications. Your ophthalmologist may prescribe eye drops containing steroids to reduce the inflammation.

Decreased tear production due to a vitamin A deficiency can cause dry eyes that are itchy or burning. Artificial tears can help relieve these symptoms. In severe cases, antibiotics may be prescribed to treat the infection.

Skin sores or rashes

Skin problems are some of the more common complications of Crohn’s disease.

Skin tags may develop around hemorrhoids in the anus. These small flaps form when the skin thickens as the swelling is reduced. Irritation may occur if fecal matter attaches to these skin tags, so good hygiene is important.

Up to 15% of people with Crohn’s disease may have sensitive red bumps (erythema nodosum) on their shins, ankles, or arms.

Some people may develop lesions (pyoderma gangrenosum) on these same areas of the body. The lesions can be treated with topical ointments or antibiotics.

Another skin problem associated with Crohn’s disease is Sweet’s syndrome, a rare condition that causes fever and painful lesions on the arms, face, and neck. It’s usually treated with corticosteroid medications.

Crohn’s disease doesn’t have a cure, but it is treatable. You can go into remission with targeted and consistent treatment. Without treatment, the chronic inflammation that exists causes the condition to progress and produce complications.

People with Crohn’s disease have the same life expectancy as those who don’t have it, according to the Crohn’s & Colitis Foundation.

However, some of the complications of Crohn’s disease, such as colon cancer, fistulas, and bowel obstructions, may be fatal if left untreated. This is why it’s important to see your doctor if you’re experiencing the symptoms of Crohn’s disease.

You should see a doctor if you’re experiencing any of these symptoms:

  • bloody bowel movements
  • abdominal pain
  • episodes of diarrhea that aren’t relieved by over-the-counter medications
  • unexplained fever or weight loss

If you have concerns about treatment, talk to your doctor. The more information you have, the better equipped you’ll be to make the best treatment choices.