According to the Crohn’s & Colitis Foundation (CCF), skin disorders affect about 20 percent of people with inflammatory bowel disease, a broad term that refers to both Crohn’s disease and ulcerative colitis. Some of these disorders, such as psoriasis, can get worse in the winter because freezing temperatures and dry indoor air can leave the skin parched. Moisturizing with ointments like petroleum jelly (such as Vaseline), using a humidifier, and avoiding coarse, potentially irritating fabrics can help combat this issue, says Amanda Moon, MD, a pediatric dermatologist at Children’s Hospital of Philadelphia. For more serious symptoms that can’t be controlled with these measures, it’s important to see a dermatologist because you may need prescription medication to treat psoriasis, she notes. Additionally, because Crohn’s — and many of the medications that treat it — can weaken the immune system, people with the disease may also be more susceptible to skin infections, Dr. Moon says. “Sometimes, a bacterial infection could be making psoriasis or other rashes worse,” she says. A dermatologist can prescribe medication to treat the infection.

Erythema Nodosum “Erythema nodosum causes tender pink or red bumps to form under the skin, usually on the shins," says Laura Winterfield, MD, an associate professor of dermatology at the Medical University of South Carolina in Charleston. Though erythema nodosum is unpredictable, it may accompany a Crohn’s flare and then fade when symptoms are back under control. Wearing compression stockings and elevating the legs can help manage erythema nodosum, which is more common in women and affects about 2 to 10 percent of people with Crohn’s, according to the CCF.Pyoderma gangrenosum causes painful red-to-purple pus-filled blisters that turn into skin ulcers. It’s more likely to occur in areas where skin has been damaged or irritated, a condition called pathergy. “Although these ulcers look infected, they’re usually not, so antibiotics don’t help," says Dr. Winterfield. Pyoderma gangrenosum isn’t preventable, but avoiding skin trauma may decrease the risk. Treatment may require high doses of steroids.Aphthous Stomatitis This skin condition causes small mouth ulcers, also called canker sores. They commonly occur in people with Crohn’s when intestinal symptoms flare up, and they go away when symptoms subside. They are painful, sensitive, and usually form between the gums and lower lip or on the tongue. A balanced Crohn’s diet and vitamin supplements may help prevent canker sores. Medicinal mouthwashes may also help alleviate symptoms.

Localized skin conditions around the anal area of a person with Crohn’s disease include skin tags and skin cracks called anal fissures. These result from the swelling and irritation caused by Crohn’s. You can best prevent and manage them with good hygiene, warm baths, and soothing ointments. Other rare skin problems associated with Crohn’s include:

Acrodermatitis enteropathica, a Crohn’s complication caused by a zinc deficiency. Zinc is important for optimal nutrition, but people with Crohn’s may lose some of the mineral due to bouts of diarrhea. “This skin condition causes a pink, scaly rash that usually appears around the mouth or anal area,” says Winterfield. Replacing zinc in the diet makes the rash go away.Epidermolysis bullosa acquisita is rare but has been reported in scientific literature as a complication of Crohn’s disease. It causes blisters on the hands, knees, elbows, and feet, according to the National Institutes of Health’s Genetic and Rare Diseases Information Center. It also occurs in other diseases of the immune system. Treatment may require steroids and immune-suppression drugs.

Crohn’s Skin Conditions Caused by Medication

Beyond skin conditions that stem from the condition itself, some Crohn’s medication may lead to adverse skin reactions.

Sulfasalazine, a drug used to block inflammation in Crohn’s, may cause an allergic skin rash, hives, or itching. “In most cases this medication can be replaced with another that does not contain sulfa,” says Winterfield.Steroids are an important medication used to block inflammation in Crohn’s. Long-term steroid use can cause thinning of the skin, loss of color in the skin, and aggravation of acne, according to the Mayo Clinic.Anti-tumor necrosis factor (TNF) drugs, the latest class of medication used for Crohn’s disease, may cause a skin rash at the injection site. “Psoriasis is another immune disease that may be linked with Crohn’s, and anti-TNF drugs may trigger psoriasis in some people,” notes Winterfield. Indeed, in a report published in 2019 in the journal Archives of Rheumatology, the authors described five case reports in which people with Crohn’s experienced developing or worsening psoriatic skin lesions while receiving this kind of therapy. Another report, published in June 2014 in Digestion, describes 13 people with Crohn’s who had developed psoriasis while receiving anti-TNF drugs. Their skin symptoms improved once their anti-TNF treatment was discontinued. Other research, published in January 2016 in the Scandinavian Journal of Gastroenterology, suggested that some patients with Crohn’s who use such drugs might also develop eczema, which makes the skin itchy and red. Dermatologists will often work closely with gastroenterologists to determine a therapy that treats Crohn’s but doesn’t exacerbate skin issues, Moon says.

“It is important to remember that many of these skin conditions occur in people who don’t have Crohn’s disease, and also that people with Crohn’s disease can have skin conditions that aren’t caused by Crohn’s,” says Winterfield. Learning as much as you can about Crohn’s and working closely with your doctor to keep Crohn’s under control is the best way to prevent complications. Always check in with your doctor if you develop any new symptoms, including ones that have nothing to do with digestive issues. Additional reporting by Ashley Welch