Crohn’s Disease Rash: Symptoms, Causes, & Treatment

Crohn’s disease, a form of inflammatory bowel disease (IBD), is an autoimmune disease that causes inflammation in the digestive tract. Symptoms range from mild to severe and can include abdominal pain, diarrhea, loss of appetite, weight loss, and fever.

Around 6%–40% of people with Crohn’s will have symptoms that occur outside of the digestive tract. The most common of these extraintestinal complications affect the skin, causing rashes, hives, and lesions. This article discusses how Crohn's can impact the skin.

Common Crohn’s-Related Skin Symptoms

Skin symptoms associated with Crohn’s disease can appear on any part of the body. They can manifest in various ways, ranging from red bumps on the legs to sores in the mouth to sores in the anal region.

These Crohn’s-related skin symptoms can be broken down into six different types:

• Erythema nodosum is the most common type of skin problem in Crohn’s disease. It causes tender red bumps or nodules under the skin that typically occur on the legs. These bumps often accompany other symptoms such as fever, aches, and chills.
• Pyoderma gangrenosum is also very common with Crohn’s disease and appears as lesions on the skin. These lesions typically begin as small blisters or raised spots that then progress into deep ulcers. They most commonly form on the legs but can occur anywhere on the body. They can be painful and, if severe, can cause scarring.
• Oral lesions can be caused by Crohn’s itself or by certain medications used to treat the disease. These can occur on the gums, cheeks, tongue, and lips. Oral lesions in Crohn’s can appear as ulcers on the inside of the cheeks, fissures or deep grooves in the tongue, swollen lips or gums, and cracked or red corners of the mouth known as angular cheilitis.
• Sweet’s syndrome causes tender red bumps or blisters on the skin of the upper body. They can also appear on the face and neck. Though fairly rare in Crohn’s disease, the bumps usually appear when the disease is active. Fever is common with Sweet’s syndrome.
• Perianal lesions are lesions around the anus that are common with Crohn’s. They can appear as fistulas, fissures or cracks in the skin, abscesses, skin tags, and hemorrhoids.
• Metastatic Crohn’s disease is a rare skin-related symptom of Crohn’s that occurs in areas that are unrelated to the gastrointestinal tract. The lesions of metastatic Crohn’s disease appear as plaques and occur most often on the legs, vulva, penis, torso, and face. They can develop before a Crohn’s diagnosis.

Along with the skin, Crohn’s can also affect the joints, eyes, liver, and gallbladder.

Causes

While researchers are still investigating the exact cause of skin involvement in Crohn’s disease, there are several known factors.

Some skin issues are caused directly by Crohn’s or by its inflammatory response. Others share the same disease process as Crohn’s or are caused by certain treatments used to treat Crohn's.

• Perianal lesions and metastatic Crohn’s share the same changes to the cells of the skin as the changes that occur in the gastrointestinal tract lining due to the disease itself.
• Pyoderma gangrenosum and Sweet's syndrome are thought to be caused by the same disease process as Crohn’s.
• Erythema nodosum and oral lesions seem to be secondary to the inflammatory response that occurs with Crohn’s. These tend to develop when Crohn’s is more active and primary symptoms are more pronounced.

Skin lesions have also been associated with anti-TNF treatments, or tumor necrosis factor (TNF) inhibitors, that are commonly used to treat Crohn’s.

Malnutrition (lack of proper nutrition) or malabsorption (difficulty absorbing nutrients) may also cause some skin symptoms. Due to the inflammation of the intestinal tract in Crohn’s, it may be harder to absorb nutrients and vitamin deficiencies can occur.

A zinc deficiency can manifest as crusted plaques on the arms or legs or near the mouth. Deficiencies in iron, vitamin C, and vitamin B12 are also common in Crohn’s.

Treatments

Treatment for skin issues related to Crohn’s disease depends on the type of skin disorder.

Medications are the most common form of treatment. These include but are not limited to:

• Corticosteroids that can be taken orally, injected directly into the lesion, or applied topically
• Immunosuppressants, such as cyclosporine or Imuran (azathioprine)
• Immunomodulators or anti-TNF drugs, such as Remicade (infliximab) and Humira (adalimumab)
• Antibiotics, such as Azulfidine (sulfasalazine)
• Anti-interleukins, such as Skyrizi (risankizumab-rzaa) or Stelara (ustekinumab)

Sometimes your current medication may be the cause of the skin problems and you may be taken off the drug. However, do not discontinue any drug without your healthcare provider’s consent.

For skin issues due to a vitamin deficiency, supplementation may be all that is needed to relieve symptoms.

If the skin involvement is caused by a flare, or worsening of Crohn’s symptoms, getting the Crohn’s under control can help relieve some of the skin symptoms.

Summary

Some people with Crohn's disease will experience symptoms outside of the digestive tract, including skin issues. Rashes and lesions can form as a result of Crohn's or from medication used to treat Crohn's.

A Word From Verywell

While managing a chronic illness like Crohn’s can be overwhelming, taking note of new symptoms and being in communication with your healthcare provider can help you control the disease. Understanding the different ways that Crohn’s disease can manifest on the skin can help you manage your symptoms. If you live with Crohn’s and notice new lesions or rashes on your body, talk to your healthcare provider so that they can create a treatment plan best suited for you.