Ulcerative colitis is an inflammatory bowel disease (IBD) that causes inflammation and ulcers (sores) in the innermost lining of the colon and rectum. It can also affect other parts of the body, most commonly the skin. Up to 35% of people with ulcerative colitis have a skin condition. Ulcerative colitis can lead to many skin changes, including various types of rashes.

Types of Ulcerative Colitis Rashes

If you have ulcerative colitis and develop a new rash, it may be related to the condition. Below are some skin rashes associated with ulcerative colitis, their appearance, how they develop, and available treatments.

Erythema Nodosum

Appearance: Small, round nodules or plaques that are red, firm, and painful to touch. These most commonly form on the shins and ankles but may also appear on the arms. Joint and muscle pain may accompany the rash.

Development: Typically appears during a flare but can also occur just before one.

Treatment: Managed by addressing IBD. In some cases, steroids or antibiotics are prescribed.

Pyoderma Gangrenosum

Appearance: Begins as small, painful blisters on the shins (sometimes on the arms). These blisters may merge and grow into deep, chronic ulcers.

Development: The link between this condition and ulcerative colitis flares or severity is unclear.

Treatment: Can heal when IBD is under control. Severe cases may require antibiotics, topical ointments, and wound care.

Bowel-Associated Dermatosis-Arthritis Syndrome (BADAS)

Appearance: Lesions may appear as small, raised bumps, pus-filled bumps, or plaques on the arms or torso. These may be itchy, painful, or red.

Development: Originally linked to bowel bypass surgery, now believed to be associated with gastrointestinal conditions like ulcerative colitis and bacterial overgrowth.

Treatment: Often involves antibiotics, steroids, and biologics.

Sweet Syndrome

Appearance: Tender, red plaques or nodules on the upper body. Symptoms may include fever, headache, and joint pain.

Development: Typically appears suddenly.

Treatment: Treated with anti-inflammatory medications and by managing the underlying condition.

Acrodermatitis Enteropathica

Appearance: A flaky rash usually seen on the face, hands, feet, and perineum (the skin between the anus and genitals).

Development: Caused by zinc deficiency, often due to chronic diarrhea.

Treatment: Zinc supplements, possibly delivered directly to the intestines. Compresses and moisturizers may help soothe the skin.

Pyoderma Vegetans

Appearance: Blisters, plaques, or patches, often around the groin and underarms. These rashes darken as they heal.

Development: Believed to result from an immune system abnormality.

Treatment: Treatments for IBD often help resolve this skin condition.

Why Does Ulcerative Colitis Sometimes Cause a Rash?

When experiencing a flare, the inflammation affecting the digestive system can also impact the skin. The skin is one of the most visible areas where inflammation manifests, though ulcerative colitis can affect multiple systems, including the eyes, lungs, kidneys, and cardiovascular system. The exact cause of skin-related symptoms is unclear, but factors such as genetics, the environment, microbiome changes, and immune system activity may play a role.

Other Possible Skin Changes

Beyond rashes, ulcerative colitis can cause additional skin-related issues:

  • Psoriasis: Chronic inflammatory skin condition that commonly coexists with ulcerative colitis.

  • Vitiligo: Loss of skin pigmentation seen in some individuals with ulcerative colitis.

  • Anal fissures: Small tears in the anus lining, which can be painful and itchy.

  • Acne: May result from steroid medications used to treat ulcerative colitis.

  • Skin cancer: A potential risk due to long-term immunosuppressive therapy. Sunscreen use is recommended.

  • Vasculitis: Inflammation of blood vessels causing red patches on the skin. This usually improves once IBD is treated.

Treatment

Managing ulcerative colitis and related skin conditions often requires a comprehensive treatment plan. In many cases, improving IBD symptoms also alleviates skin issues. The main treatment goal is to reduce inflammation and maintain remission, as there is no known cure for ulcerative colitis.

In other instances, skin conditions may require separate treatment depending on the specific diagnosis, which can include medications, topical agents, or even surgical interventions. If medication is the suspected cause of the rash, healthcare providers may adjust the treatment plan accordingly.

When To Seek a Healthcare Provider

Consult a healthcare provider or dermatologist if you experience a skin rash that:

  • Covers most of your body

  • Blisters or turns into open sores

  • Is accompanied by a fever

  • Spreads quickly

  • Causes significant pain

  • Affects your eyes, lips, mouth, or genitals

A proper diagnosis will help determine whether the rash is related to ulcerative colitis and inform the necessary treatment approach. Some skin conditions may appear before a flare or when intestinal inflammation is severe.

A Quick Review

Almost half of individuals with ulcerative colitis will experience symptoms outside their digestive system, with skin rashes being among the most common. Common rashes include erythema nodosum and pyoderma gangrenosum, though others may also occur. Rashes may precede or accompany a flare. Controlling ulcerative colitis can help resolve many skin issues, although specific treatments may be needed in some cases.