Long-Term Complications

Complications of Crohn’s disease usually develop from the repeated inflammation and thickening and thinning of the bowel walls that compromise their functional integrity. Also, Crohn’s patients may suffer from a lack of nutrition. The body is unable to absorb nutrients properly because of the damaged intestine, so patients often experience weight loss and chronic diarrhea due to malabsorption. They may also suffer side effects due to lack of specific nutrients in the body.

Intestinal Blockage

This is the most common complication of Crohn’s disease.Thickening of the intestinal wall from swelling and scarring can narrow the passage through your intestines. This can cause constipation, discomfort, and abdominal pain.


If left untreated, ulcers can tunnel through the intestinal walls and attach to surrounding organs, such as the skin, bladder, vagina, anus, or rectum. These tunnels, called fistulae, can then become infected. It may also mean waste empties through your skin, vagina, or in your urine. Some fistulae can be treated with medicine; others may require surgery.

Deep ulcers or fissures that have eaten through the walls of the small intestine and colon can create tunnels from the intestine to nearby organs. Depending on which organs these tunnels attach to, they can cause a variety of problems.

  • Abdominal abscess: If the tunnel attaches to an empty space in the abdominal cavity, it can cause an infection and fill with pus (an abdominal abscess). Abdominal abscesses can cause high fevers, abdominal pain, and abdominal tenderness.
  • Fistula: If the tunnel reaches an adjacent organ, it becomes a channel, or fistula.
  • Enteric-vesicular fistula: A fistula that forms between the intestine and the bladder is called an enteric-vesicular fistula. This can cause frequent urinary tract infections. It may also cause you to pass gas and feces during urination.
  • Enteric-cutaneous fistula: A fistula between the intestine and the skin is called an enteric-cutaneous fistula. This can cause an opening on the skin of the abdomen from which pus and mucous may discharge.
  • Colonic-vaginal fistula: A fistula between the colon and the vagina is called a colonic-vaginal fistula. This can cause gas and feces to pass through the vagina.
  • Anal fistula: A fistula from the intestines to the anus is called an anal fistula. This can lead to mucous and pus discharge from the fistula’s opening around the anus.

Nutrition Deficiencies

Nutrition deficiencies are common complications of Crohn’s disease. Scarred and damaged tissues are not as capable of absorbing much-needed vitamins, nutrients, and calories. This is also true if you have chronic diarrhea—your intestines don’t have time to absorb any nutrients. These complications can lead to the following:

  • anemia (too-low levels of iron)
  • malnutrition (not enough nutrients)
  • malabsorption (inadequate or poor absorption)

Vitamin B-12 is absorbed in the terminal ileum, a part of the small intestine most often affected by Crohn’s disease. If inflammation in the terminal ileum is a chronic problem, you may have an increased risk of developing anemi, so your blood doesn’t have enough red blood cells to adequately supply your body with the oxygen your muscles and tissues need. Vitamin B-12 helps prevent anemia and promotes normal nerve function and development. If your B-12 levels remain consistently low, your doctor may suggest weekly B-12 shots to increase your stores of B12 and subsequent monthly monthly B-12 shots to maintain appropriate levels.

Complications in Children

Children with Crohn’s disease may have impaired growth and delayed sexual development due to malnutrition and vitamin or mineral deficiencies.