Ulcerative colitis is a long-term condition that causes inflammation in the large intestine and the rectum. It can also cause skin problems.

This article explores how skin conditions are related to ulcerative colitis (UC), a type of inflammatory bowel disease (IBD).

It also considers how to reduce skin problems during a flare-up and when to visit a doctor.

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Many skin conditions are associated with UC. These are explored below.

Erythema nodosum

Erythema nodosum is the most common skin issue for people who also have UC. Approximately 3–10% of people with UC may develop erythema nodosum.

Erythema nodosum causes tender red nodules on a person’s arms or legs. These nodules may look like bruises.

In people with UC, this skin rash tends to appear during a flare-up and goes away when UC is in remission.

Pyoderma gangrenosum

Pyoderma gangrenosum is a common skin problem that may affect people with UC. A 2021 study estimates that people with UC are up to 15 times more likely to have pyoderma gangrenosum than those without the condition.

This skin rash begins as a cluster of blisters on the shins, ankles, or arms. It often spreads and can form deep ulcers. If not kept clean, the ulcers may become infected.

Researchers believe a problem with the immune system that may be linked to the cause of UC causes pyoderma gangrenosum.


Psoriasis is a skin condition caused by a problem with the immune system. It leads to discolored, patchy skin covered with a buildup of dead skin cells.

Many people with UC and other types of IBD are also affected by psoriasis.

A 2015 study found some genetic links between the genes that cause IBD and those that cause psoriasis. More research is needed to understand these connections fully.


Hives are red raised spots that may appear as a rash anywhere on the body. They form due to a reaction in the immune system.

Sometimes, people react to the medication they take for UC, which can cause chronic hives.

Skin cancer

People with IBD have an increased risk of melanoma. Thiopurine, a mainstay treatment for IBD, can also increase the risk of developing skin cancer.

Bowel-associated dermatosis-arthritis syndrome

Bowel-associated dermatosis-arthritis syndrome (BADAS) is a condition where small bumps form on the upper chest and arms in addition to other symptoms. These bumps can then form pustules, causing discomfort. BADAS may also cause lesions on the legs.

Researchers do not fully understand the cause, but they think it may relate to inflammation as a result of bacteria in the gut. Having IBD makes it more likely a person will develop BADAS.

Pyodermatitis-pyostomatitis vegetans

Pyodermatitis vegetans and pyostomatitis vegetans are two associated skin conditions. Pyodermatitis vegetans causes red pustules that burst and form scaly patches in the armpit or groin. Pyostomatitis vegetans involves pustules in the mouth.

The two conditions are typically grouped together and called pyodermatitis-pyostomatitis vegetans (PPV).

This condition is associated with UC, though it is rare.

Sweet syndrome

Sweet syndrome is another condition that is linked to UC flare-ups.

When a person has Sweet syndrome, small red or purple bumps on the skin develop into painful lesions. They often form on the upper limbs, face, and neck.


Vitiligo is a skin condition that destroys the pigment-producing cells in the skin. Vitiligo may lead to white patches forming anywhere on the body.

Researchers think an immune disorder causes vitiligo. According to MedlinePlus, around 15–25% of people with vitiligo also have another immune disorder, such as UC.

Cutaneous vasculitis

Cutaneous vasculitis occurs when small blood vessels under the skin become inflamed and die. The inflammatory reaction leads to purple spots on the skin of the legs or ankles, called purpura.

The condition results from inflammation and is linked to UC flare-ups. Cutaneous vasculitis typically goes away when UC is in remission.

UC can be a painful and uncomfortable inflammatory condition affecting the large intestine and the rectum.

When a person has UC, ulceration and inflammation develops in the colon’s lining. These can produce mucus and bleeding.

The main symptoms of UC are:

  • abdominal pain
  • ongoing problems with diarrhea
  • blood or mucus in stools
  • the need to pass stool often
  • extreme tiredness
  • loss of appetite
  • weight loss

Ulcerative colitis flare-ups

Although UC is a long-term condition, a person with UC may go weeks or months without symptoms. This is called remission.

Periods of remission may be followed by flare-ups, where the person experiences many UC symptoms.

During a flare-up, a person with UC may experience symptoms in addition to those that affect the digestive system. These include:

  • rashes or patches of red, swollen skin
  • swollen or painful joints
  • mouth ulcers
  • red, irritated eyes

Why do skin rashes appear during flare-ups?

The inflammation in the body that causes UC can also affect the skin. This can lead to swollen and painful skin rashes.

According to a 2015 study, skin problems affect up to 15% of people with IBD, which includes people with UC.

The medication a person might take to manage their UC symptoms may also cause skin problems.

People with UC often experience skin problems during flare-ups, so the best way to manage skin conditions related to UC is to manage UC itself.

A doctor can help a person with UC find the best methods for their symptoms and lifestyle.

When flare-ups occur, the following may help reduce skin problems:

  • taking corticosteroids to reduce inflammation
  • eating a well-balanced diet to promote skin health
  • keeping the affected skin clean to reduce infection risk
  • covering the affected area with bandages
  • taking over-the-counter pain relievers

If a skin issue is particularly troublesome, it is a good idea to speak with a doctor to get a proper diagnosis and the right treatment.

If skin conditions are recurring or worsening over time, it is a good idea to talk with a doctor about the best way to manage them.

A doctor can also help a person with UC find ways to manage their condition as a whole.