Inflammatory bowel disease (IBD) and hidradenitis suppurativa (HS), also called acne inversa, appear to have several connections. A person with IBD is at increased risk of HS and those with HS are at greater risk of developing IBD. Additionally, people with both HS and IBD are more likely to have signs of active IBD disease than those with only IBD. Although more research is needed to determine the specifics of this complex relationship, there is an association between these diseases.

What Is Inflammatory Bowel Disease?

IBD is the umbrella term for a group of autoinflammatory diseases of the digestive tract. The two main types of IBD are ulcerative colitis (UC) and Crohn’s disease (CD). Although sometimes mistakenly confused with irritable bowel syndrome (IBS), IBD’s symptoms are the result of the immune system causing inflammation in the gut. The symptoms of HS are a result of similar immune system irregularities. Common IBD symptoms include diarrhea, cramping, nausea, weight loss, and fatigue. HS and IBD can both be extremely, even debilitatingly, painful. As many as 70 percent of people with IBD experience pain as part of their condition. IBD, like HS, can vary in severity from person to person.

Connections Between HS and IBD

The skin and the digestive system have more in common than one might think. Epithelial cells make up the outer layers of both the skin and the lining of our digestive tract.

Disease Characteristics

HS and IBD are both immune-mediated inflammatory diseases. Immune-related inflammatory diseases are caused by an abnormal immune response that activates the same inflammatory pathways in the brain and spinal cord (known as the central nervous system). This inflammation is expressed differently. HS causes inflammation in the skin where apocrine glands (a type of sweat gland) exist. IBD’s inflammatory response affects the lining of the gastrointestinal tract, like the intestines and stomach.

It can be challenging to tell the difference between HS and CD, specifically in cases of perianal CD, which is defined by inflammation near the anus. Around 25 percent of people with CD develop drainage tunnels between the skin and digestive tract called perianal fistulas. People with HS can develop similar-looking lesions.

Causal Factors

Although the exact causes of HS and IBD remain undetermined, it’s widely believed that a combination of genetic factors and environmental factors are responsible. Some of the same genes that are thought to increase a person’s susceptibility to HS, increase susceptibility to IBD.

Millions of microscopic organisms coexist on your skin and in your gut. They all keep one another in check, maintaining a healthy environment that is balanced and well functioning. This is called the microbiome. Some researchers believe an upset to the microbiome’s fragile balance (genetic or environmental) may play a role in the start of both diseases.

Risk Factors

Smoking is a significant risk factor for HS and IBD. Smoking has also been linked to more severe symptoms and more frequent flares in people with both conditions. It has been shown to alter the gut microbiome, which may be one way in which it increases HS and IBD risk. Fortunately, this risk drops dramatically once a person stops smoking.

Comorbid Conditions

It’s common for people with a chronic illness like HS to develop other chronic conditions (comorbidities). Both HS and IBD are linked to comorbidities including arthritis, psoriasis, and similar autoimmune conditions when the immune system mistakenly attacks the body. Obesity, or having excessive fat that presents a risk to one’s health, is another condition more common among people with HS and IBD. People with HS and IBD are also at increased risk of certain types of cancer because of the long-term effects of chronic inflammation.

IBD (CD, in particular) is one of the most commonly diagnosed comorbid conditions in people with HS. One case-control study showed those with IBD are twice as likely to have or develop HS as the general population. People with CD are more likely to have HS than people with UC. Among people living with HS and IBD, two-thirds have CD. HS is especially prevalent among people with perianal CD who have active fistulas.

Treatment

Some of the same classes of medication (e.g., biologics, corticosteroids) used to treat IBD can also be used to treat HS. Adalimumab (Humira) is a biologic drug known as a tumor necrosis factor inhibitor that fights inflammation in many conditions by suppressing the immune system. Adalimumab is the only biologic currently approved for use in treating HS. However, in a small number of cases, HS developed as a drug reaction or side effect when adalimumab was used to treat other immunological conditions such as arthritis and psoriasis.

Managing IBD When You Have HS

Just as your HS is best treated by a dermatologist, your IBD is best diagnosed and treated by a physician with digestive tract expertise (gastroenterologist). If you have IBD and HS, talk to your health care providers about the best options for managing both conditions in close coordination with one another.

Lifestyle Changes

Depending on the severity of your symptoms, HS and IBD can be effectively comanaged by adhering to your prescribed treatment regimen and living a healthy lifestyle. Small, but effective, changes to one's day-to-day habits and choices may help manage both HS and IBD symptoms. Some lifestyle changes shown to help manage IBD include:

• Getting plenty of rest and high-quality sleep
• Making daily exercise part of your routine
• Maintaining a healthful, well-balanced diet (extra anti-inflammatory foods may help)
• Learning what your disease triggers are
• Avoiding things and situations that worsen your symptoms
• Quitting smoking and avoiding secondhand cigarette smoke
• Managing stress by using relaxation strategies such as deep breathing techniques, mindfulness and meditation exercises, yoga, tai chi, or massage

Managing a Dual Diagnosis

Although one is a skin condition and the other is a condition of the digestive system, some treatments may be effective for both HS and IBD. For example, some biologics such as infliximab (Remicade) and ustekinumab (Stelara) used to treat IBD have also been shown to be effective in treating people with HS. Surgery is also a treatment possibility for both conditions in certain situations.

You Are Not Alone

On myHSteam, the social network for people with hidradenitis suppurativa, more than 24,000 members come together to ask questions, give advice, and share their stories with others who understand life with HS.

Are you living with both HS and IBD? How do you manage your dual diagnosis? Post a comment below. Or better yet, start a conversation with people who understand what life with HS can be like on myHSteam.