Crohn's Rashes and Skin Complications - Health Central

Crohn's disease is an inflammatory bowel disease that occurs in the gastrointestinal (GI) tract, and typically causes symptoms like abdominal pain, diarrhea, rectal bleeding, weight loss, and fatigue. But for many people, the condition can lead to surprising symptoms elsewhere in the body. In fact, around 40% of patients, the condition also causes problems outside of the GI tract according to the National Library of Medicine.

One place Crohn's commonly shows up: on your skin, with rashes and other lesions. If you're dealing with a Crohn's disease and find yourself developing a rash or other skin symptoms, here's what might be happening—and how you can manage the problem.

How Crohn's Can Affect Your Skin and Pictures of Crohn's Disease Skin Rashes

Having Crohn's can raise the risk for several types of skin conditions. Per the Crohn's & Colitis Foundation, some of the most common Crohn's-related skin problems include:

• Aphthous stomatitis

• Erythema nodosum

• Psoriasis

• Pyoderma gangrenosum

• Skin cancer

If a lot of that looks like Greek (OK, Latin) to you, you're not alone. Here's a bit more about what each term refers to.

Aphthous Stomatitis

Doctor-speak for canker sores, aphthous stomatitis is marked by small, ulcer-like sores that crop up around the gums, lower lip, or the base of the tongue. The bumps can be painful, especially when eating. Some people notice a burning sensation in the affected area a few days before the bump actually appears, according to the National Library of Medicine.

Up to 30% of people with Crohn's will get aphthous stomatitis sores from time to time, estimates DermNet. While inflammation is likely a contributor, it's also possible they relate to nutrient deficiencies, reports Crohn's and Colitis Canada. Often, the sores tend to show up right before new or worsening GI symptoms. "When people see them, they know they're starting to flare," says Arun Swaminath, M.D., chief of gastroenterology at Lenox Hill Hospital in New York City.

Pictures of Aphthous Stomatitis

Erythema Nodosum

An inflammatory condition whose name literally means "red bumps," erythema nodosum (EN) causes large red, rash-like bumps on the shins or ankles. The bumps are often tender, painful, and warm to the touch, and tend to turn purplish or brown after several weeks, notes the Cleveland Clinic. Sometimes EN can also cause a fever, joint pain, or fatigue.

EN is the most common Crohn's-related skin condition. An American Journal of Clinical Dermatology report on erythema nodosum estimates that up to 15% of people with Crohn's could be affected, with women at higher risk than men. Symptoms tend to flare up in tandem with a person's GI Crohn's symptoms, but there's reassuring news: "By getting the Crohn's under control, a person's EN symptoms should improve as well," says Amit Desai, M.D., a gastroenterologist at Texas Health Presbyterian Hospital Dallas.

Pictures of Erythema Nodosum

Psoriasis

Anyone can have psoriasis, an autoimmune condition where skin cells build up and form thick, dry, red or silvery patches that can sometimes get worse with skin injuries. But the chances are higher for people with Crohn's—up to 2.5 times higher compared to those without Crohn's, found a meta-analysis on psoriasis and irritable bowel disease (IBD) in JAMA Dermatology.

Experts don't fully understand the relationship between Crohn's disease and psoriasis. "We do know that both are inflammatory autoimmune conditions that have some overlapping pathways," explains Dr. Swaminath. "A lot of people have looked into the question of whether [Crohn's and psoriasis] symptoms are part of the same disease." On the other hand, "we know that one condition can exist without the other," he adds.

Pictures of Psoriasis

Pyoderma Gangrenosum

Pyoderma gangrenosum (PG) is more common in people with ulcerative colitis than in those with Crohn's, but it can also occur alongside Crohn's disease, affecting around 1% of patients, according to a paper in the journal Clinical, Cosmetic, and Investigational Dermatology. The condition is marked by small, red bumps that transform into large, open sores over a few days.

Sores often form on the legs but can develop anywhere on the body, the Mayo Clinic notes. "A classic scenario is someone having abdominal surgery and developing pyoderma right at the site of an ostomy," Dr. Swaminath says.

Similar to EN, PG symptoms often happen when a person's Crohn's is flaring and tend to ease up as their GI symptoms are brought under control, the Crohn's & Colitis Foundation points out. But that's not always the case. According to Dr. Swaminath, sometimes people whose Crohn's symptoms are well-managed will still end up with PG sores.

Pictures of Pyoderma Gangrenosum

Skin Cancer

Having Crohn's disease can increase a person's skin cancer risk by around 1.8-fold, found one Clinical Gastroenterology & Hepatology analysis. It's possible that abnormal immune system reactions that occur with Crohn's could fuel the growth of cancerous skin cells, the authors theorized. Immunomodulators and biologics used to treat Crohn's, which suppress immune system activity, might also play a role in skin cancer development.

Despite this, experts agree that the benefits of prescribed therapies greatly outweigh any potential skin cancer risks. "This is not a reason to avoid these medications," Dr. Desai emphasizes. You'll just need to be more vigilant about keeping an eye on your skin. Dr. Desai and Dr. Swaminath both recommend that patients with Crohn's are screened annually by a dermatologist for suspicious lesions. When growths are spotted earlier, they're easier to treat.

Pictures of Skin Cancer

Other Crohn's Skin Problems

Less often, a Crohn's diagnosis can bring along other skin problems as well. Here are some more possible offenders, per the Crohn's & Colitis Foundation:

• Acrodermatitis enteropathica, a rash associated with a zinc deficiency

• Epidermolysis bullosa acquisita, in which minor skin injuries lead to blistering

• Sweets syndrome, an inflammatory condition with a painful rash

• Vasculitis, or inflammation of blood vessels which shows up on skin as red spots

• Vitiligo, in which patches of skin lose their color

Causes of Crohn's Disease Skin Conditions

It's no secret that Crohn's disease can bring on a host of skin conditions. But the why isn't so clear. "The exact mechanism is poorly understood, but it is thought that a diseased gut may trigger an immune response in our bodies, which attacks certain targets in our bodies," Dr. Desai explains. "There may be similar targets in the skin as there are in our gut, so patients may develop associated skin conditions if those targets overlap."

It's also possible that these immune responses could be triggered by the microbiome. A study on psoriatic diseases and inflammatory bowel disease published in Nature, for instance, suggested that certain bacteria driving harmful immune system reactions affecting the gut could spur on harmful immune system reactions affecting the skin as well.

In the case of psoriasis, sometimes treating Crohn's may actually trigger the skin condition. While relatively uncommon, TNF-inhibitors used to manage Crohn's like secukinumab, brodalumab and ixekizumab, can actually trigger or worsen psoriasis in some patients, reports an Italian study of IBD patients taking these drugs.

When this happens, experts call it paradoxical psoriasis. (The paradox being that a medication used to treat one autoimmune problem ends up creating another one.) In that case, "stopping the drug will often clear up the skin problem," Dr. Swaminath says.

Treatments for Crohn's Disease Skin Conditions

Many Crohn's-related skin problems tend to worsen when a person's Crohn's is flaring. That can mean a whole set of extra symptoms to deal with when you're already feeling lousy, but there's a flip side: "Many times, getting Crohn's under control will result in improvement of skin conditions," Dr. Desai says.

Depending on your Crohn's symptoms and how severe they are, per the Mayo Clinic, your gastroenterologist might prescribe:

• Corticosteroids like prednisone or budesonide

• Immunomodulators like azathioprine or methotrexate

• Biologics like inflixumab, adalimumab, or vedoluzumab

If your Crohn's treatment isn't doing enough to help your skin, or if you need support while the Crohn's meds kick in, a dermatologist can help. For itch related to psoriasis, for instance, they might prescribe an ointment or cream for faster relief.

When to See a Doctor for Crohn's Disease Skin Problems

Given the close relationship between Crohn's and dermatologic issues, there's a good chance that your GI doc is on the lookout for skin symptoms. "Part of the initial evaluation in the gastroenterology office includes a discussion about skin conditions," says Dr. Desai.

That said, you should let your gastroenterologist know if you notice any new or worsening skin rashes, lesions, or growths. They may refer you to a dermatologist to figure out whether the problem is related to your Crohn's—and figure out the best way to help you feel better.

Notes: This article was originally published April 25, 2023 and most recently updated April 26, 2023.