Crohn’s disease: these telltale marks on the skin

Presse Santé

Crohn’s disease is a type of inflammatory bowel disease (IBD). It is a chronic or long-lasting condition that causes inflammation of the digestive tract. It can also cause skin problems, such as rashes. About 40 percent of people with Crohn’s disease have non-digestive symptoms, which most commonly affect the skin. In about 25% of cases, these symptoms appear before the person is diagnosed or even before they experience digestive symptoms. In this article, we describe and explain the skin symptoms of Crohn’s disease by type.

Crohn’s disease on the skin

A rash typical of Crohn’s disease causes red skin lesions with chronic inflammation. The rash may appear as swollen blisters, which may appear in clusters or as a single lesion.

Erythema nodosum

One of the most common causes of Crohn’s disease is erythema nodosum. It can cause painful, swollen bumps to appear on red skin and usually develops on the legs, usually below the knees. This rash has many possible causes, including bacterial and viral infections. It is therefore important to consult a doctor to get the correct diagnosis.
Other skin disorders

Here are some other types of rashes and symptoms that people with Crohn’s disease can develop:

– “tag” of the skin

These are small, extra skin growths that may be flesh-colored, pink, or darker than the skin. Some people think they look like moles. They are more common in places where there is a lot of friction, such as the genital area.

– Vasculitis

This group of diseases refers to a type of inflammation of the blood vessels that can cause patches of redness on the skin.

– Gangrenous pyoderma

This skin condition is common in people with Crohn’s disease who have skin disorders. It causes painful, swollen blisters that can open and become ulcers. They often grow larger over time.

– Injuries related to taking medications

Some people develop blisters on the skin as a side effect of Crohn’s disease treatment. This is because the treatment weakens the immune system, which can increase the risk of skin infections.

– Oral injuries

Some people with Crohn’s disease develop blisters or sores in their mouth. Others develop gum disease. About 10% of people with the disease develop skin problems in the mouth.

– Vitiligo

Sometimes IBDs can cause Vitiligo, which is a loss of pigment in the skin.

– Psoriasis

This condition causes peeling, itching, redness or inflammation of the skin. For most Crohn’s disease skin lesions, treatment focuses on reducing Crohn’s disease-related inflammation using disease-modifying agents, such as biologics.
In some cases, a person may need additional treatment, such as dental surgery, removal of skin tags, or antibiotic treatment for an infected blister.

Vulvar Crohn’s disease

Crohn’s disease rarely affects the vulva or vagina, but it is possible.
If this happens, a person may notice the following:

– swelling of the lips
– skin growths called fistulas
– painful blisters, sores or lesions on the vagina
– skin tags

Doctors treat this condition with drugs to control the inflammation caused by Crohn’s disease. A doctor may also surgically remove painful or large skin growths.

Anal Crohn’s disease

Perianal Crohn’s disease means that a person has inflammation in or around the anus.
Here are some examples of symptoms a person might experience:

– Abscesses: Some people develop small pockets of infection. An abscess may look like a very swollen pimple or look like a painful bump under the skin.

– Cracks: A cleft is a tear in the skin of the anus. It can cause symptoms similar to those of a hemorrhoid, such as pain and bleeding. A person may notice a patch of red skin, but it may also be too deep in the anus to be visible.

– Stenosis: Sometimes the inflammation due to Crohn’s disease makes the anus very tight. A person may notice that their anus is small, tight, or unusual and that it is painful or impossible to have a bowel movement.

Anal skin tag

Some people with Crohn’s disease develop anal skin tags.
Skin tags look like fleshy, loose bumps. They can be as small as a freckle or larger than the tip of a pencil eraser. They can be the color of the skin, but also darker or lighter than a person’s skin. Skin tags are nothing to worry about. However, they can cling to clothing or other objects and bleed or become infected as a result. As with cutaneous Crohn’s disease, treatment focuses on reducing inflammation due to the disease and treating any infections. A doctor can also remove skin tags.

Orofacial Crohn’s disease

Orofacial Crohn’s disease affects the face, mouth, or both. It may be more common in children than in adults.

Some symptoms are:

– deep, painful sores in the mouth
– swollen lips which may crack and bleed
– swollen gums
– Crohn’s rash on the face, such as clusters of blisters or stitches.

Anti-inflammatory treatments for Crohn’s disease can be effective. Doctors may also recommend prescription mouthwashes, special diets, or additional dental care to prevent serious gum health problems.

Crohn’s disease and bowel movements

Crohn’s disease causes inflammation of the intestines and digestive tract. This can make it harder for the body to absorb nutrients from food. Changes in stool a person may notice, especially during a Crohn’s disease flare-up, include:

– Watery stools: greater difficulty in absorbing water and nutrients can lead to diarrhea. A person may have more frequent or very loose bowel movements.

– Constipation: Inflammation, particularly of the anus and rectum, can make it more difficult for stool to pass. This can lead to constipation. A person may notice that their stools are very hard or come out in small lumps.

– Presence of blood in the stool: anal fissures or constipation can cause traces of red blood in the stool. Dark, tarry stools indicate that a person may have bleeding higher up in the gastrointestinal tract, which is a medical emergency.

– Oily stools: When the body is unable to absorb nutrients such as fat, a person’s stool may appear greasy or more viscous than usual.

When to contact a doctor

Crohn’s disease can be treated. However, without treatment, it can lead to serious complications.
A person should contact a doctor if:

– have symptoms of Crohn’s disease, such as frequent diarrhea or stomach pain
– new symptoms of Crohn’s disease appear
– you think you have a skin infection
– cannot eat or drink without having severe diarrhea.


Barrett, M., et al. (2014). Crohn’s disease of the vulva.

Bernett, CN, et al. (2021). Cutaneous Crohn’s disease.

de Zoeten, EF, et al. (2013). Diagnosis and treatment of perianal Crohn’s disease.

Crohn’s disease diagnosis. (2017).

Hafsi, W., et al. (2020). Erythema nodosum.

Heymann, WR (2017). Understanding the association between orofacial granulomatosis and Crohn’s disease would be fantastic.

* Presse Santé is committed to transmitting health knowledge in a language accessible to all. IN NO EVENT, the information provided cannot replace the advice of a healthcare professional.

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