Crohn’s Disease and Skin: Symptoms, Causes & Treatment

Crohn’s disease is a chronic inflammatory condition that affects the digestive system. It is a type of inflammatory bowel disease. People who have this condition experience inflammation in their digestive tract, along with symptoms like diarrhea, abdominal pain and cramping, fatigue, and weight loss. Many people with Crohn’s disease also experience symptoms that do not affect the digestive tract but occur outside of the digestive tract. The most common area impacted by Crohn’s disease is the skin. However, the reason why Crohn’s disease affects the skin is yet unknown. Here’s everything you need to know about Crohn’s disease rash.

Crohn's Disease and the Skin


Crohn’s Disease and the Skin

The usual symptoms of Crohn’s disease involve the gastrointestinal tract, which causes symptoms like abdominal pain and cramping, bloody stools, and severe diarrhea.(1,2,3) Nevertheless, nearly 40% of people with Crohn’s disease also experience symptoms in other parts of the body, and the most commonly affected part is the skin.(4,5)

However, why exactly does Crohn’s disease affects the skin is still not clearly understood. It is believed that it might be due to certain immune factors, a reaction to Crohn’s medications, and some of the direct effects of the disease.

Crohn’s Disease and Skin Symptoms


People who have Crohn’s disease can tend to develop a variety of different skin lesions, including:

Oral Lesions

Oral lesions are lesions that occur in the mouth, and when these lesions appear, you are likely to notice the appearance of painful ulcers in inside of the mouth, especially on the lips and inside of the cheeks. Sometimes, you may also see other symptoms, including:

  • Swollen lips
  • Swollen gums
  • Cracked or red patches at the corners of the mouth – this is known as angular cheilitis(6)

Perianal Lesions

This type of lesions is located around the anus. They tend to be red and swollen and can be painful. Perianal lesions can appear like fissures or splits in the skin, ulcers, skin tags, abscesses, fistulas, or abnormal connections between any two body parts.

Pyoderma Gangrenosum


This skin condition begins with a bump on the skin that goes onto develop into an ulcer or sore with a yellow base. It is possible to have many lesions or just a single pyoderma gangrenosum lesion. This condition most commonly affects the legs. Pyoderma gangrenosum tends to happen during a relapse or flare-up of Crohn’s disease. Once the lesions heal, it can leave behind significant scarring. Nearly 35 percent of people are likely to experience a relapse of this skin condition during the next Crohn’s flare-up.(7)

Metastatic Crohn’s Disease

This is a rare condition that commonly affects the face, genitals, and extremities. It is also likely to occur in areas where two patches of skin rub together. The lesions of metastatic Crohn’s disease appear plaque-like, but in some cases, they may also appear more like ulcers. They are usually purplish or reddish in color and either appear by themselves or in clusters.(8)

Sweet’s Syndrome

Sweet’s syndrome is characterized by the appearance of tender, red papules that tend to cover your torso, head, and arms. They either grow together or occur separately to form a plaque. Other common symptoms of sweet’s syndrome include:


Erythema Nodosum

Erythema nodosum is marked by the appearance of tender red nodules or bumps that occur just beneath the skin. They are usually found on the lower extremities, especially towards the front of your shin. Chills, aches and pains, and fever also accompany erythema nodosum. This is the most common skin trouble that affects people with Crohn’s disease. It also usually coincides with a flare-up of Crohn’s, but not always.(9)

Crohn’s Disease and Other Conditions That Affect The Skin

There are many other conditions also that are linked with Crohn’s disease and cause skin symptoms. Some of these include:

In some cases, people taking a particular type of biologic drug for Crohn’s known as an anti-TNF drug can also develop skin lesions that look like psoriasis or eczema.(10)

Some vitamin deficiencies can also cause skin symptoms, as Crohn’s disease often leads to malnutrition. Some examples are as follows:

  • Iron Deficiency: Iron deficiency can lead to the appearance of red, cracked patches at the corners of your mouth.
  • Zinc Deficiency: Deficiency of zinc can cause the formation of plaques or red patches that may have pustules.
  • Deficiency of Vitamin C: A lack of vitamin C can cause bleeding underneath the skin. This causes bruise-like spots to appear on the skin.(11)

Why Does Crohn’s Cause Skin Symptoms?

The exact cause of why or how Crohn’s disease causes skin symptoms are not well understood, and researchers still continue to investigate this. However, what is known is that some types of lesions, such as metastatic and perianal lesions, appear to be caused by Crohn’s disease directly. When these lesions were biopsied and examined under a microscope, they were found to have similar features to Crohn’s disease.

Other lesions such as pyoderma gangrenosum and erythema nodosum are believed to share some disease mechanisms with Crohn’s disease. It is also believed that there are some autoimmune conditions that are the cause of skin symptoms, such as psoriasis, and they are associated with the immune response in Crohn’s disease.

Secondary factors linked to Crohn’s disease, such as medications and malnutrition, are also known to cause these skin symptoms.

Treating Crohn’s Related Skin Conditions

There are various treatments for skin lesions that are associated with Crohn’s disease. The exact treatment that your doctor will recommend for you depends on the type and cause of skin lesions you have.

Some medications can help alleviate the skin symptoms, including:

  • Antibiotics that help with abscesses or fistulas
  • Anti-TNF biologic drugs such as adalimumab or infliximab
  • Anti-inflammatory medications such as sulfasalazine
  • Corticosteroids that can be administered orally, through injection, or topically
  • Immunosuppressive drugs such as azathioprine or methotrexate

Other treatments for skin lesions include:

  • A fistulotomy, which is a surgical procedure for removing a severe fistula
  • Discontinuing the anti-TNF biologic that is causing the skin symptoms
  • Taking vitamin supplements when malnutrition is the cause of skin symptoms


Many people with Crohn’s disease are known to experience skin symptoms. There are many different types of skin lesions related to Crohn’s disease, and these can offer either due to the direct effects of the disease or due to complications caused by the disease, such as malnutrition. Certain immune factors related to Crohn’s disease can also cause skin symptoms. If you have Crohn’s disease and notice any skin symptoms, it is better to consult y our doctor at the earliest.


  1. Baumgart, D.C. and Sandborn, W.J., 2012. Crohn’s disease. The Lancet, 380(9853), pp.1590-1605.
  2. Shanahan, F., 2002. Crohn’s disease. The Lancet, 359(9300), pp.62-69.
  3. Torres, J., Mehandru, S., Colombel, J.F. and Peyrin-Biroulet, L., 2017. Crohn’s disease. The Lancet, 389(10080), pp.1741-1755.
  4. Gravina, A.G., Federico, A., Ruocco, E., Lo Schiavo, A., Romano, F., Miranda, A., Sgambato, D., Dallio, M., Ruocco, V., Loguercio, C. and Romano, M., 2016. Crohn’s disease and skin. United European Gastroenterology Journal, 4(2), pp.165-171.
  5. Bernett, C.N. and Krishnamurthy, K., 2017. Cutaneous Crohn Disease.
  6. Scully, C., Cochran, K.M., Russell, R.I., Ferguson, M.M., Ghouri, M.A., Lee, F.D., MacDonald, D.G. and McIntyre, P.B., 1982. Crohn’s disease of the mouth: an indicator of intestinal involvement. Gut, 23(3), p.198.
  7. Huang, B.L., Chandra, S. and Shih, D.Q., 2012. Skin manifestations of inflammatory bowel disease. Frontiers in physiology, 3, p.13.
  8. Leu, S., Sun, P.K., Collyer, J., Smidt, A., Stika, C.S., Schlosser, B., Mirowski, G.W., Vanagunas, A. and Buchman, A.L., 2009. Clinical spectrum of vulva metastatic Crohn’s disease. Digestive diseases and sciences, 54(7), pp.1565-1571.
  9. Marshall, J.K. and Irvine, E.J., 1997. Successful therapy of refractory erythema nodosum associated with Crohn’s disease using potassium iodide. Canadian Journal of Gastroenterology, 11.
  10. Assche, G.V. and Rutgeerts, P., 2000. Anti-TNF agents in Crohn’s disease. Expert opinion on investigational drugs, 9(1), pp.103-111.
  11. Filippi, J., Al-Jaouni, R., Wiroth, J.B., Hébuterne, X. and Schneider, S.M., 2006. Nutritional deficiencies in patients with Crohn’s disease in remission. Inflammatory bowel diseases, 12(3), pp.185-191.

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