Extra-Intestinal Complications of Crohn's Disease

Some Crohn's disease complications are not directly related to the inflammation in the small or large intestine and are called "systemic" or "extra-intestinal" side effects. These complications can include arthritis, bone loss, delayed growth in children, eye disease, gallstones, skin rashes or lesions, and mouth ulcers.

It's not known why Crohn's disease complications can occur outside the digestive tract, but in some cases, they follow the course of the disease: they worsen during a flare-up and improve during remission.

Woman having an eye exam
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Pain, swelling, and stiffness in the joints of people who have Crohn's disease may be due to peripheral arthritis. Symptoms may last for days or weeks and may migrate from one joint to another. Peripheral arthritis may improve when the underlying Crohn's disease is treated successfully, and it does not cause any permanent damage to the joints. Symptoms are treated with moist heat and rest. People with Crohn's disease may also develop other forms of arthritis, either as a complication or as an adverse effect of the medication.

Bone Loss

People living with Crohn's disease are at risk for bone loss and osteoporosis for several reasons. Calcium is important for bone health, and vitamin D is necessary for the body to absorb calcium. However, people with Crohn's disease may be vitamin D deficient, especially if the small intestine has an extensive disease or has been partly removed through surgery.

In addition, proteins called cytokines have been found in higher levels in people with Crohn's disease, especially while the disease is active. Cytokines may interfere with the removal of old bone and the creation of new bone. Other risk factors for bone loss include a low body mass index (BMI), being assigned female sex at birth, smoking, alcohol use, and older age.

General recommendations for prevention of bone loss include exercise, reducing the use of alcohol, stopping smoking, and supplementing with 1500 mg of calcium and 400 IU of vitamin D daily. For people with inflammatory bowel disease (IBD), reducing the use of corticosteroids when possible and taking a bisphosphonate drug are also helpful.

Delayed Growth in Children

Crohn's disease puts children at risk for delayed growth. Several factors affect growth in kids with Crohn's disease, including lack of appetite, a poor diet, poor nutrient absorption in the small intestine, and the use of steroids as a treatment. These factors may have a negative effect on a child's height and result in a short stature.

Eye Disease

Eye diseases that can affect people with Crohn's disease include uveitis, episcleritis, keratopathy, and dry eyes. Some eye conditions require treatment, and most will improve when the underlying Crohn's disease is effectively managed.

  • Dry eyes are caused by a lack of tears in the eyes. This lack of moisture can lead to eye irritation and eventual blindness. Dry eyes are treated with artificial tears and vitamin A supplements. If the dryness causes an infection, treatment with antibiotics may be needed.
  • Episcleritis is inflammation of the white of the eye that causes symptoms of pain and reddening. Episcleritis is treated with a vasoconstrictor or a corticosteroid.
  • Keratopathy is an irregularity in the cornea that does not cause pain or loss of vision and is therefore usually not treated.
  • Uveitis is an inflammation of the middle layer of the eyewall that causes symptoms of light sensitivity, pain, redness, blurred vision, and headache. Left untreated, uveitis could lead to blindness, glaucoma, or a detached retina. Treatment is with corticosteroids.


Bile that hardens in the gallbladder can cause gallstones. Gallstones can block the exit of bile from the gallbladder, which causes severe pain. People with Crohn's disease in the terminal ileum are at increased risk for developing gallstones; as many as 13% to 34% will experience this complication. The inflammation in the ileum prevents the absorption of bile. Bile dissolves cholesterol from food, and if this cholesterol is not broken down, it can result in gallstones. Gallstones are typically treated by surgically removing the gallbladder. Treatment with medication is less commonly used because gallstones may recur.

Mouth Ulcers

Small, shallow ulcers that occur inside the mouth are called aphthous stomatitis. Prescription mouthwashes may be used to keep the mouth clean, but no other treatment is usually needed. Mild cases may heal on their own, but topical anti-inflammatories and anesthetics may ease discomfort and promote healing.

Skin Conditions

People with Crohn's disease in the colon may develop skin tags. The skin around hemorrhoids in the perianal area becomes thickened and creates flaps. Care should be taken to keep the anal area clean, because skin tags may retain stool and lead to skin irritation. The presence of skin tags may be helpful in making the diagnosis of Crohn's disease because they are more common in people with Crohn's disease than with ulcerative colitis.

Other skin conditions that are associated with Crohn's disease are erythema nodosum and pyoderma gangrenosum. Erythema nodosum is painful red nodules that develop on the arms or lower legs, and pyoderma gangrenosum is a blister on the legs or arms that typically forms at the site of a minor trauma, such as a cut. Both of these conditions are less common in Crohn's disease than in ulcerative colitis. Erythema nodosum may affect 1% to 2% of those with Crohn's disease of the colon, and pyoderma gangrenosum may affect 1% of people with Crohn's disease.

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  • Bonheur JL, Braunstein J, Korelitz BI, Panagopoulos G. "Anal skin tags in inflammatory bowel disease: New observations and a clinical review." Inflammatory Bowel Diseases 14; 1236-1239 1 May 2008.

  • Crohn's and Colitis Foundation of America. "Extraintestinal Complications: Bone Loss." 1 May 2012.

  • Crohn's and Colitis Foundation of America. "Extraintestinal Complications: Eye Disorders." 1 May 2012.

  • Crohn's and Colitis Foundation of America. "Extraintestinal Complications: Liver Disease." 1 May 2012.

  • Crohn's and Colitis Foundation of America. "Extraintestinal Complications: Skin Disorders." 1 May 2012.

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.