Ulcerative Colitis and Pyoderma Gangrenosum: Are They Linked?

Medically Reviewed by Sabrina Felson, MD on June 06, 2022
5 min read

People who have an inflammatory bowel disease like ulcerative colitis often have problems caused by inflammation in other parts of their bodies. One of these is a skin condition called pyoderma gangrenosum. It’s very uncommon, but it can be extremely painful and disfiguring. In rare cases, people with other related diseases or who get complications from this condition have even died.

It’s an inflammatory skin condition that causes large open sores called ulcers. Pyoderma gangrenosum is different in different people, but the classic form has these typical features:

  • It starts as one or more small red bumps that look like a rash or an insect bite.
  • Very quickly, the bumps progress to a large sore.
  • The edges of the sore may be blue or purple.
  • It usually has pus in the center.
  • The sores tend to be very painful.
  • Several smaller ulcers can grow together into one larger one.
  • They happen most often on your lower legs, but they can be almost anywhere.

You may also have these symptoms:

  • Fever
  • Joint pain
  • Muscle aches
  • Feeling generally unwell

The name is misleading because doctors were mistaken about its cause when they first identified it more than 100 years ago. The term ”pyoderma gangrenosum” describes an infection that makes pus and leads to tissue death. But the disease isn’t an infection, and it isn’t contagious.

It isn’t clear exactly what causes pyoderma gangrenosum. But research is pointing to a problem with the immune system. Also, the ulcers show a lot of inflammation and contain an unusually high number of infection-fighting white blood cells.

Doctors tend to have a hard time diagnosing pyoderma gangrenosum. When someone comes in with a skin ulcer, it’s much more likely to be from a different cause. There’s no single test or symptom that shows you have it. That means your doctor may take a small piece of skin to look at under a microscope or do blood tests to try to rule out other things.

A delay in getting the right diagnosis can allow it to spread and become harder to treat. And some treatments that work on other kinds of sores – like cutting away dead skin and tissue – can make this condition worse.

It’s very rare. Fewer than 1 in 100,000 people get pyoderma gangrenosum. It’s more common in women than in men. Most people are diagnosed between the ages of 20 and 50. Things that make you more likely to get it include:

Underlying conditions. Half of the time, people who get pyoderma gangrenosum also have another disease, usually something that involves an overactive immune system. The most common are:

  • Ulcerative colitis
  • Crohn’s disease
  • Rheumatoid arthritis
  • Leukemia

But having ulcerative colitis doesn’t mean you’re going to get pyoderma gangrenosum. Fewer than 3% of people with an inflammatory bowel disease develop the skin condition. It does mean that you should be on the lookout for any suspicious bumps or a rash and call your doctor right away.

Skin injury. Pyoderma gangrenosum can also form in spots where your skin has been damaged. Doctors have to watch for it after surgery, especially if you have an inflammatory bowel disease. Some intestinal procedures leave you with a tube coming out of your side to remove waste. Pyoderma gangrenosum can happen in the skin surrounding that opening.

Medicines: People taking certain drugs as part of cancer or thyroid disease treatment have gotten pyoderma gangrenosum. These include:

  • Gefitinib
  • Pegfilgrastim
  • Propylthiouracil

But it isn’t clear whether the drug triggered the skin response or if it’s linked to the illness the drug is treating.

Doctors say the two diseases are associated. It’s more than just a coincidence if you get them both. But it isn't clear exactly how they’re connected.

Some of the same abnormal immune system behavior seen in people with ulcerative colitis is also seen with pyoderma gangrenosum. That points to the possibility of one central cause for both problems.


  • Many times the two diseases appear together, but more often they don’t. Usually you already know you have ulcerative colitis when you get pyoderma gangrenosum. But sometimes the skin problem is the first symptom that leads a doctor to test you for ulcerative colitis.
  • It doesn’t seem to matter whether your ulcerative colitis is active or in remission. Sometimes, pyoderma gangrenosum improves with good control of your underlying condition. But you can also get it when you’re in remission, and even after you’ve had your colon removed.
  • An even more rare variant of this disease, called pustular pyoderma gangrenosum, mainly affects people with inflammatory bowel disease. That does appear to be more closely linked to the ups and downs of ulcerative colitis.

When you have both ulcerative colitis and pyoderma gangrenosum, you’re likely to get some kind of anti-inflammatory medication. These include:

  • Steroids
  • Immunosuppressants
  • Biologic drugs called TNF inhibitors

You may get these drugs as a pill, a medicine you apply to the wound, or as an injection. Some of these medications are also used to treat inflammatory bowel disease on its own. So it’s hard to say whether your ulcers get better because of the medication or because your ulcerative colitis is getting better.

It’s important to keep the sores clean and covered so they’re less likely to get infected. Infections are more common if you’re taking drugs that suppress your immune system.

Proper wound care includes:

  • Sterile dressings
  • Antibiotic creams or ointments
  • Pain medication

If the sores are very large and deep, or don’t get better with treatment, you may need to get help at a hospital or burn center. You might also need a skin graft to cover a large ulcer that’s having trouble healing.

This disease can be very hard to live with. You may be in a lot of pain and be concerned about how the sores look. If you have trouble going about your daily life, ask your doctor to refer you to a support group or mental health service.

It’s very hard to know how someone will do with this disease. It can be mild and clear up on its own. Or it can be serious with very large, deep sores that extend into tissues beneath the skin. In general, the sicker you are with other conditions, the worse your pyoderma gangrenosum is likely to be.

Usually, people recover with treatment. But the ulcers can last for months and leave large scars. Rarely, people can die from complications directly related to the ulcers, like sepsis.

It’s common for pyoderma gangrenosum to come back after it’s healed. A cut or other damage to your skin can trigger it. You may be able to lower your chances of having it again if you can keep your ulcerative colitis under control.