arm and leg with skin condition

Crohn's Disease and Skin Conditions

Last updated: October 2022

Though Crohn's disease (CD) mainly affects the digestive tract, it often comes with conditions that affect other areas of the body. Around 40 percent of people living with CD develop one of these conditions.1

Most commonly, conditions that occur with CD affect the skin. Almost 25 percent of people even have a skin condition that appears before they are diagnosed with CD.1

A wide variety of skin conditions are linked to CD. Some are direct effects of CD on the skin. Others occur because of the inflammation or immune system changes that come with CD.1

Conditions that are an extension of Crohn's disease

Two conditions in which CD extends to the skin are continuous/contiguous lesions and metastatic Crohn's lesions.2

Continuous/contiguous lesions

Because CD affects the entire gastrointestinal (GI) tract, ulcers (also called lesions) sometimes occur around the mouth or anus. Common complications include perianal fissures and fistulas.1

Fissures are small tears in and around the anus that can cause painful bowel movements. Fistulas are connections between the intestines and skin. This can cause leakage of feces through the connection.1

Metastatic Crohn’s lesions

This is a more rare complication where CD ulcers appear on the skin. These ulcers can occur anywhere, but they usually occur in skin folds or legs. They may look like a red, irritated area or like an open wound.2

These areas are called "metastatic" because they are not directly connected to the intestines. However, scientists have proved that these ulcers are similar to intestinal CD ulcers under a microscope.2

Conditions associated with Crohn's

The following conditions can happen in anyone, not just those living with CD. However, they commonly occur in people with CD because they are linked to the same immune system changes that cause CD.2

Aphthous stomatitis

Aphthous stomatitis is the scientific name for "canker sores." These are small but sometimes painful ulcers that can occur in the mouth.1,3

Anyone can get canker sores. However, they commonly appear during CD flares and may be more severe in people with CD. Severe canker sores may need to be treated with steroid medicines or medicated mouthwashes.1,3

Erythema nodosum (EN)

EN is a common skin disorder associated with CD. It also can occur with other autoimmune diseases and infections, or when taking certain medicines.1,3

EN appears as tender, red bumps over the shins. These bumps can also occur on the ankles or arms. They are more common in women. They often occur before a flare and will improve as the flare improves.1,3

Psoriasis

Psoriasis is a skin condition that can occur on its own but also affects people living with CD. Scientists believe that some of the gene changes (mutations) that are involved with CD may also be involved in psoriasis.2

Psoriasis appears as light pink patches on the arms, legs, and trunk. The patches are often covered in silver or gray-colored dry skin.2

Reactive diseases

The diseases in this category are similar to CD in that they cause excessive inflammation in the body. Experts think this inflammation is caused by abnormal immune system function.2

Pyoderma gangrenosum (PG)

This is one of the most severe skin conditions that occurs with CD. It most often occurs on the shins or ankles, but it also can appear on the arms.1-3

PG starts as a collection of small blisters that join and then become a deep, painful ulcer. These ulcers can be caused by minor injury to the skin and may be hard to heal. Other symptoms may include fever, muscle pains, and fatigue.1-3

Sweet syndrome

This is a rare condition that mainly affects women. It usually appears as fever and tender, red spots on the arms. Though Sweet syndrome can occur with CD, it is also linked to some upper respiratory infections, gastrointestinal infections, and tumors.1,3

Drug-related and diet-related conditions

Some skin conditions that occur with CD can be caused by prescription drugs or poor nutrition.

Drug rashes

Sometimes, the medicines used to treat CD can cause rashes. Sulfasalazine may cause a rash in people who have an allergy to sulfa drugs. Steroids can also cause stretch marks, puffiness, or acne.3

Skin cancer

Because CD is an autoimmune disorder, it is often treated with drugs that suppress the immune system (immunosuppressants). These drugs can increase your risk of developing skin cancer. If you are taking immunosuppressant drugs, wear sunscreen regularly and limit the amount of sun you get.3

Rashes caused by nutritional deficiencies

CD causes inflammation in the intestines as well as diarrhea. Because of this, you may struggle to absorb all the nutrients you need. Important nutrients may be lost in bowel movements. The resulting low levels of certain vitamins can cause a variety of skin rashes.2

These are not all the skin conditions that can occur with CD. If you have skin symptoms that concern you, talk to your doctor.

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