Research has shown that both conditions may occur together, suggesting a possible link between Crohn’s disease and HS. They also share risk factors, such as smoking.

Crohn’s disease is one type of inflammatory bowel disease (IBD). It is a chronic gastrointestinal (GI) condition affecting any part of the digestive tract.

Crohn’s causes inflammation and GI symptoms. Hidradenitis suppurativa (HS) is another chronic condition primarily affecting the skin, resulting in inflamed nodules that can sometimes swell and rupture.

This article explores the link between Crohn’s disease and HS and their shared risk factors. It also looks at the incidence rates of the two conditions, symptoms, and treatment.

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According to a 2023 study, IBD appears to have a causal effect on HS, whereas HS does not appear to affect IBD.

However, other studies suggest that people with HS may have an increased risk of IBD.

A 2022 literature review compared three cases of Crohn’s disease and HS occurring together. Researchers found that both conditions can present similar characteristics.

Some research, particularly case reports or series, shows there is an association between TNF-alpha inhibitors like Humira — which is a drug that can treat both conditions — and HS.

Still, more research is necessary to explain this link further.

Risk factors

A 2023 study proposes that IBD and HS result from genetic and environmental factors.

Research from 2022 suggests that although Crohn’s disease and HS are separate conditions, they share some similar risk factors. These include:

Additional risk factors for both conditions may include immune dysregulation and microbiome changes.

Immune dysregulation occurs when the body cannot stop or hamper the way the immune system reacts. Microbiome changes relate to the disruption in the normal flora of microbes in certain areas of the body, such as the gut.

Research from 2021 discusses how several studies have indicated that people with Crohn’s disease may have a greater risk of HS.

One 2023 study corroborated that the risk of HS in people with IBD is 9 times higher than in the larger population.

A 2017 Danish study found that the prevalence of Crohn’s disease was 0.8% for people with HS versus 0.3% for people without Crohn’s disease.

Meanwhile, a 2017 cross-sectional study found that IBD had a prevalence of 3.3% in 1,076 people with HS. The prevalence of Crohn’s disease was 2.5%, and the prevalence of ulcerative colitis, another type of IBD, was 0.8%.

There are certain symptoms of each condition that a doctor checks for.

Crohn’s disease symptoms

Crohn’s disease may affect any part of the GI tract. Symptoms vary from person to person. The following are some common ones:

Serious complications associated with Crohn’s disease symptoms include:

  • fissures, which are cuts or tears in and near the anus
  • fistulas, which are abnormal intestinal connections leading to stomach acid leaking
  • strictures, which refers to the narrowing of the intestines

HS symptoms

Possible symptoms of HS include:

  • burning or itchy skin
  • uncomfortable lump under the skin
  • tender, deep nodules that may join together
  • painful abscesses that may break open
  • blackhead spots

The most common areas where symptoms occur include:

  • armpit
  • groin
  • the area close to the anus
  • the area between the anus and the genitals
  • below the breasts

HS and Crohn’s disease symptoms

Both HS and Crohn’s disease can cause:

  • abscesses in the area between the anus and genitals or groin region
  • involvement of sinus tracts, or tunneling wounds, under the skin
  • other conditions (for example, Crohn’s and HS share an association with arthritis)
  • atypical immune responses

Assessing both conditions

When people with HS have accompanying digestive symptoms, doctors typically perform a GI examination to determine the cause of these symptoms.

Similarly, in people with Crohn’s disease who also have HS-like skin lesions, especially in the areas around or close to the anus and genitals, doctors closely assess a person to differentiate HS from an anal fistula.

Some treatments may be effective for both Crohn’s disease and HS. However, doctors may also use specific methods to treat the conditions separately.

HS treatment

First-line treatment for HS includes antibiotics. This might involve local or systemic antibiotics with anti-inflammatory properties, such as tetracycline.

Sometimes, doctors may opt for a combination of antibiotics, such as clindamycin and rifampicin.

Research from 2021 also proposes surgical treatments for HS, including:

  • incision and drainage for pain relief and to help control inflammation
  • local or extensive incision to treat moderately severe HS
  • extensive resection and reconstruction to help HS that has not responded to medications

Read more about HS surgery.

Crohn’s disease treatment

Medications for Crohn’s disease include:

  • aminosalicylates, which help treat inflammation
  • corticosteroids
  • biologics, a drug class that targets the immune system
  • immunomodulatory drugs, which help change the immune system’s response to the disease

Possible surgical options include:

  • small bowel resection
  • subtotal colectomy, or removal of a big portion of the large intestine
  • proctocolectomy, or removal of the entire large intestine
  • ileostomy

Read more about IBD medications.

Treatments for both

More recently, research has shown biologics that target tumor necrosis factor, known as anti-TNF agents, can effectively relieve moderate to severe HS symptoms. Biologics are a common treatment option for people with IBD.

The research found that anti-TNF agents provided significant relief for people with HS and accompanying Crohn’s disease symptoms.

Adalimumab (Humira) and infliximab (Remicade) are two examples of anti-TNF agents.

Research demonstrates that IBD appears to have a causal effect on HS. Other studies suggest that people with HS may have an increased risk of IBD.

Some researchers note that Crohn’s disease treatment may also contribute to the development of HS. Crohn’s disease and HS also share similar risk factors, such as diabetes and smoking.

Crohn’s disease leads to GI symptoms such as persistent diarrhea and rectal bleeding. HS tends to cause skin-related lesions, such as painful nodules.

Both conditions may also lead to abscesses around the anus, genital, and groin regions. Therefore, doctors must assess skin lesions to determine an accurate diagnosis and rule out any possible complications of Crohn’s disease.

Biologic treatments have shown effectiveness in treating both Crohn’s disease and HS. Surgical options for each condition may also be used, such as incision and drainage of HS, or bowel resection or complete removal of the large intestine for Crohn’s disease.