Hidradenitis suppurativa (HS) is an auto-inflammatory disease in which hair follicles fill with bacteria, keratin, and sweat. This buildup can cause painful lesions and abscesses containing pus. It’s unclear what causes the condition.

Crohn’s disease is a form of inflammatory bowel disease (IBD). It can cause inflammation anywhere throughout the digestive system. This affects how the body absorbs nutrients. Symptoms include cramping, bleeding, and diarrhea.

At one time, these conditions were seen as completely unrelated. But research is now showing that there are some potential connections.

People who live with HS are more likely to develop Crohn’s disease. If you have HS, it’s a good idea to be aware of the signs of Crohn’s. It’s important to get the right diagnosis and treatment to manage your day-to-day life with these conditions.

Crohn’s disease and HS are both inflammatory conditions, and they start with an immune response. The immune system is designed to target injuries or invaders.

When the immune system is triggered, it increases blood flow to the area to bring in more immune cells. This is a good thing if the target is something harmful, like pathogenic bacteria.

In some cases, inflammation is triggered inside the body for no obvious reason and doesn’t shut off. The result can be swelling, pain, and damage to otherwise healthy areas of the body. There’s ongoing research exploring how inflammatory conditions may all be related.

Another possible link between these conditions involves changes in your microbiome. The microbiome refers to the trillions of microscopic living organisms in and on our bodies. The majority live in our digestive system, but many also live on our skin.

There are changes in the microbiomes of people with Crohn’s disease and HS. People with Crohn’s disease have changes in the bacteria colonies in their gut. In HS, bacteria in and on the skin, hair follicles, and sweat glands may trigger inflammation.

For both conditions, it’s unclear what happens first. Does the microbiome change, increasing the risk for disease? Or does the disease result in changes to the microbiome?

A 2017 study also suggests that smoking can increase your risk for both conditions. For people who already have HS or Crohn’s disease, smoking can make symptoms worse.

The symptoms of HS in the early stages can be similar to other skin conditions and can even be misdiagnosed as severe acne. It’s thought to affect about 1 percent of people.

People with HS are more likely to have Crohn’s disease compared to the general population. There’s also an increased risk for other inflammatory conditions when you have HS.

A large meta-analysis from 2019 looked at the connection between Crohn’s disease and HS. They found an over twofold greater incidence of Crohn’s disease in people with HS.

Both conditions can affect the perianal area (the skin around your anus), and the lesions look quite similar. It’s possible that some cases of HS are overlooked in people with Crohn’s disease, as healthcare professionals may assume the lesions are related to Crohn’s.

If you live with a chronic condition like HS, it’s important to monitor for any health changes. It’s always best to find things early. Talk with your doctor about your concerns so that they can start you on the right treatment.

Painful abscesses can occur in the perianal area as part of HS or Crohn’s disease. If you have HS and have skin symptoms in that area, it’s recommended that you see a gastroenterologist (a doctor who specializes in the digestive system). They can better assess if it’s part of your HS or another issue.

Here are some common signs and symptoms of Crohn’s disease:

  • abdominal cramping
  • blood in the stool
  • nausea and vomiting
  • severe diarrhea
  • low iron levels (anemia)
  • fatigue
  • low appetite
  • unexplained weight loss

There’s no specific test to diagnose Crohn’s disease, and other conditions can cause similar symptoms.

Your doctor will ask about your medical and family history. They’ll also ask you for more details about your symptoms. Afterward, they may order one or more of the following tests:

  • Blood test. A high white blood cell count revealed in a blood test may indicate inflammation or an infection. Low red blood cells may be a sign of blood loss or anemia, which is common in Crohn’s disease.
  • Stool test. A stool test can look for signs of inflammation. It can also screen for parasites or other sources of infection.
  • Upper endoscopy. This is a test that uses a small flexible scope with a light and a camera. A doctor guides it through the upper part of your digestive system. The esophagus, stomach, and small intestine can be checked for damage or inflammation.
  • Capsule endoscopy. To do this test, you swallow a small pill with a camera inside. It takes pictures of your entire digestive tract. This test won’t be done if you have narrowing in any part of your digestive tract.
  • Colonoscopy. A colonoscopy is another type of scope that looks for damage or inflammation. It explores the lower part of the digestive tract, including the rectum, large intestine (colon), and the lower part of the small intestine.

There are different medications available to reduce the immune response and improve symptoms. Your treatment plan will depend on the symptoms and severity of your disease.

Crohn’s disease and HS share some of the same inflammatory proteins. Some biologic medications can be used to treat both conditions. These include:

  • Adalimumab (Humira). This injectable medication is a type of anti-tumor necrosis factor-alpha therapy (anti-TNF). It stops the action of specific proteins released by the immune system. It’s shown to reduce disease activity in both HS and Crohn’s.
  • Ustekinumab (Stelara). This medication is a type of monoclonal antibody. It’s an established treatment for Crohn’s disease. More recently, it’s been shown to help with HS symptoms. This medication targets IL-12 and IL-23 proteins. Higher levels of these inflammatory proteins are found in both Crohn’s disease and HS.
  • Guselkumab (Tremfya). This medication targets the IL-23 protein to reduce inflammation. There have been case studies showing it’s effective for both HS and Crohn’s disease. However, more research is needed.

Other medications that may be part of your treatment include:

  • Corticosteroids. This type of medication reduces inflammation and helps to lessen the immune response. These meds are used in a variety of inflammatory conditions.
  • Antibiotics. These may be used to treat an infection.

Other treatments specifically for Crohn’s disease include:

  • sulfasalazine and 5-aminosalicylates (5-ASA)
  • anti-diarrhea therapies
  • surgery

Other treatments for HS include:

  • oral retinoid medications
  • anti-inflammatory medications
  • topical creams
  • laser hair removal

People with HS have a greater higher chance of developing Crohn’s disease. Both are inflammatory diseases. A change in the microbiome may also contribute to these conditions.

It’s wise to watch for any changes in your digestive health. If you notice new symptoms, talk with your doctor. They may refer you to a gastroenterologist to help ensure that you get the right diagnosis and treatment.