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Crohn's disease skin problems: When to see your doctor

Kathleen Blanchard's picture
Erythema nodosum: Courtesy Wikimedia Commons

Crohn's disease and ulcerative colitis can also affect your skin. When should you see your doctor for treatment and what does it mean?


If you have Crohn's disease or ulcerative colitis you could be susceptible to other health problems that are worth noting. It's important to know when to see the doctor. Inflammatory bowel diseases that include Crohn's and UC can cause skin problems and arthritis.

Skin problems from Crohn's disease

Two skin problems that can develop if you have Crohn's disease are erythema nodosum and pyoderma gangrenosum.

Erythema nodosum starts as painful nodules under the skin. You might feel weak, have a fever or achy joints, much like the flu.

The nodules might be warm to touch. When they start to heal they change colors from red or purplish to brown or yellow, much like a bruise.

Seventy-five percent of people with erythema nodosum also develop arthritis, according to

Pyoderma gangrenosum often begins much like a bite - such as a spider. Small red bumps that appear and then turn into an ulcer can be extremely painful. The skin condition is thought to be the result of immune system dysfunction that occurs with Crohn's and other autoimmune diseases.

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Fortunately it is not common.

When to see your doctor

If you have Crohn's disease and develop a skin problem you should see your doctor for treatment. It's generally not safe to attribute any skin redness, itching, swelling or other to having IBD if you're not sure.

Medications to treat Crohn's disease can cause allergic reactions that means the offending medications should not be continued. Steroids can cause the skin to easily bruise.

Skin problems associated with Crohn's disease and ulcerative colitis doesn't mean IBD is worsening or severe. Researchers suspect some people with Crohn's disease are more prone to develop skin rashes because of certain interactions between their particular genes and the environment.

Other reasons for skin problems include nutritional deficiencies, such as B12 that can cause dark pigmentation of the skin and dry scaly lesions, which also makes it important to see your doctor and not brush off skin redness, itching, bruising, excessive dryness or other new problems with your skin.

References and resources:

"Significance of erythema nodosum and pyoderma gangrenosum in inflammatory bowel diseases: a cohort study of 2402 patients"
Farhi, D. et al

Canadian Family Physician
"Cutaneous lesions and vitamin B12 deficiency"