Crohn’s disease can cause a rash of swollen lesions to appear on the body. There are several medications that can help ease symptoms, such as corticosteroids and anti-inflammatory medications.

Crohn’s disease is a type of inflammatory bowel disease (IBD) that can cause inflammation in the digestive tract. It can lead to symptoms like abdominal pain, diarrhea, and weight loss.

The most common area where symptoms occur outside of the digestive tract is often the skin. Crohn’s can cause painful lesions to develop on the body. A lesion is where parts of the skin have an abnormal appearance to the skin around it.

On light skin tones, this may appear pink or red, and on dark skin tones they may take on a violet, gray, black, or brown appearance.

Keep reading to learn more about what a Crohn’s disease rash looks like and how it can be treated.

People with Crohn’s disease can develop a rash that can present on the body in several different ways. Let’s explore some of them in more detail below.

Perianal lesions

Perianal lesions are located around the anus. They can be swollen, and often painful.

Perianal lesions can take on a variety of appearances, including:

Oral lesions

Lesions may also occur in the mouth. When oral lesions appear, you may notice painful ulcers in the inside of your mouth, particularly on the inside of the cheeks or lips.

Sometimes other symptoms may be present, including:

  • a split lip
  • cracked patches at the corners of the mouth, which is called angular cheilitis
  • swollen lips or gums

Erythema nodosum

Erythema nodosum is characterized by red tender bumps or nodules that occur just under the skin. On light skin tones, they may appear red, and on dark skin tones they may look violet, gray, brown, or black.

They’re often found on your lower extremities, particularly on the front of your shin. Fever, chills, aches, and pains may also occur.

Erythema nodosum is the most common skin manifestation of Crohn’s disease. It can often coincide with a flare-up.

Pyoderma gangrenosum

This condition starts with a bump on the skin that eventually develops into a sore or ulcer. You can have a single pyoderma gangrenosum lesion or many lesions. The most common location is the legs.

Like erythema nodosum, pyoderma gangrenosum can often happen during a flare-up. When the lesions do heal, there can be significant scarring. About 35% of people can experience a relapse.

Sweet syndrome

Sweet syndrome involves tender papules that typically cover your head, torso, and arms. They can occur separately or grow together to form a plaque.

Other symptoms of Sweet syndrome include fever, fatigue, and body aches.

There are many other potential causes of skin symptoms in people with Crohn’s disease that can occur alongside the condition. They can include:

Reactions to medications

In some cases, skin lesions can be caused by a type of biologic medication called an anti-TNF drug. These lesions can look like eczema or psoriasis.

Associated conditions

There are various conditions that are associated with Crohn’s disease and may also cause skin symptoms. Some examples include:

Vitamin deficiencies

Crohn’s disease can lead to malnutrition, including vitamin deficiencies. A variety of these can cause skin symptoms. Examples include:

  • zinc deficiency, which can cause patches or plaques on the body that may also have pustules
  • iron deficiency, which can cause cracked patches at the corners of the mouth
  • vitamin C deficiency, which can cause bleeding under the skin and bruise-like spots to appear

The skin symptoms associated with Crohn’s disease can appear very diverse, depending on their type and location.

Scroll through the following pictures for some examples of what they may look like.

Further research is still needed to understand exactly how Crohn’s disease causes skin symptoms.

However, this is what we do know so far:

  • Some lesions, such as perianal lesions, may be directly caused by Crohn’s disease. When biopsied and examined with a microscope, the lesions have similar features to the underlying digestive disease.
  • Other lesions, such as erythema nodosum and pyoderma gangrenosum, are believed to share disease mechanisms with Crohn’s disease.
  • Some autoimmune conditions that cause skin symptoms, like psoriasis and SLE, are associated with Crohn’s disease.
  • Secondary factors related to Crohn’s disease, such as malnutrition and medications used in treatment, can also cause skin symptoms.

So, how could this all fit together? Like other autoimmune conditions, Crohn’s disease involves the body’s immune system attacking healthy cells. This is what leads to the inflammation associated with the condition.

Animal studies have shown that an immune cell called a Th17 can worsen autoimmune responses in IBD Crohn’s disease. Th17 cells are also associated with other autoimmune conditions, including those that can affect the skin. This means these cells could possibly form a link between Crohn’s disease and many of its associated skin symptoms.

However, additional research is needed to address the link between Crohn’s disease and the skin.

There are a variety of potential treatments for skin lesions that are related to Crohn’s disease. The specific treatment that you receive will depend on the type of skin lesions that you have.

Examples of medications that a healthcare professional may prescribe to help ease symptoms include:

Other potential treatments include:

  • discontinuing an anti-TNF biologic if it’s causing skin symptoms
  • suggesting vitamin supplements when malnutrition has caused a vitamin deficiency
  • performing surgery to remove a severe fistula, or fistulotomy

In some cases, skin symptoms may occur as a part of a Crohn’s disease flare-up. When this happens, managing the flare-up can also help to ease skin symptoms.

If you have Crohn’s disease and develop skin symptoms that you believe are related to your condition, consider speaking with a healthcare professional. They may be able to perform a biopsy to determine what’s causing your symptoms.

Generally speaking, it’s always a good rule of thumb to speak with a healthcare professional if you notice skin symptoms that:

  • cover a large area
  • spread quickly
  • are painful
  • have blisters or fluid drainage
  • occur with a fever

Crohn’s disease can also increase the risk of certain cancers, such as non-melanoma skin cancer. It’s recommended for people with Crohn’s to see a dermatologist annually for a skin check.

Many people with Crohn’s disease will experience symptoms that affect areas other than the digestive tract.

One of these areas is the skin.

There are many different types of skin lesions associated with Crohn’s disease, such as:

  • perianal lesions
  • erythema nodosum
  • pyoderma gangrenosum
  • oral lesions
  • Sweet’s syndrome

Treatment can depend on the type of lesion. It may often involve taking a medication to help relieve your symptoms.

If you have Crohn’s disease and notice skin symptoms that you think may be related, consider speaking with a healthcare professional.