Hidradenitis suppurativa (HS) is a chronic skin disease that causes lesions and painful abscesses in areas like the armpits, groin, and undersides of the breasts. If you were diagnosed with HS, you might wonder how the condition started or why you developed it.

In this article, we’ll review what causes HS and eight common risk factors.

Causes of Hidradenitis Suppurativa

The cause of HS is still not fully understood. It was once thought to be an autoimmune disease — a condition where the immune system mistakenly attacks the body’s own tissues. However, newer research has reclassified HS as an autoinflammatory condition.

Unlike autoimmune diseases, which involve targeted attacks by antibodies, autoinflammatory conditions are driven by overactivity in the body’s innate immune system — its first line of defense — leading to widespread inflammation without a specific target.

This distinction matters because it helps guide researchers and doctors toward treatments that focus on calming generalized immune overreactions, rather than targeting specific antibodies.

One theory is that HS develops when the immune system overreacts to blocked hair follicles, triggering ongoing inflammation. Hormones also appear to play a role in the condition.

HS most often affects skin areas with apocrine glands (sweat glands), such as the armpits and groin. However, newer studies suggest these glands are less significant in the development of HS than previously thought.

While researchers have established that both family history and environmental factors influence a person’s risk for developing HS, it’s still unclear why some people develop it and others don’t.

Risk Factors for Hidradenitis Suppurativa

It’s important to note that while science is good at finding correlations — or apparent relationships — between factors and disease, correlation does not prove the factor causes the disease. Many risk factors for HS have been identified and are being studied, but none have been proven to directly cause HS.

Risk Factor 1: Genetics

HS doesn’t appear to be directly inherited from parents in any clear genetic pattern. However, roughly a third of people with HS have a relative with the condition. Researchers have linked some cases of HS to mutations (changes) in genes that affect how skin cells and the immune system work — especially in genes that help regulate inflammation. Studies are ongoing to better understand how these gene changes contribute to HS.

Risk Factor 2: Gender

According to DermNet, women are about three times more likely than men to develop HS. However, the disease is often more severe in men. In general, autoimmune diseases strike women more often than those same diseases strike men. A Stanford Medicine study showed, in the U.S., up to 80 percent of people with an autoimmune disease are women.

Risk Factor 3: Hormones

Sex hormones likely play a role in the development of HS. Researchers believe this is true because:

• HS rarely develops before puberty.
• HS symptoms become worse before menstrual periods for some individuals.
• HS rarely occurs after menopause.
• Many people experience improvement in their symptoms during pregnancy or when they take hormonal birth control, such as the combined oral contraceptive pill.

Risk Factor 4: Ethnicity

Ethnicity seems to influence the chances of getting HS. Black people are more likely than those of other backgrounds to develop HS, according to a study in Cureus. HS is rare in people with Asian heritage.

Risk Factor 5: Smoking

Researchers have identified several environmental and lifestyle factors that seem to be linked to HS in some people, including smoking. HS is more common among people who smoke. Smoking is also associated with a higher number of body parts affected by HS and a weaker response to HS treatment. That said, HS also occurs among people who don’t smoke.

Risk Factor 6: Obesity

Obesity is a risk factor for developing HS and is also believed to worsen HS symptoms. People with higher body weight may experience more friction and sweating with movement, both of which can aggravate HS.

Obesity is the term for having a body mass index (BMI) score of 30 or higher. It’s worth noting that obesity is itself a complex condition that involves both inherited genes and environmental factors, such as diet, exercise habits, food culture, and socioeconomic circumstances. HS also occurs among people who do not have obesity or higher body weights.

Risk Factor 7: Certain Medications

HS can be triggered by certain drugs, including TNF-alpha inhibitors. TNF-alpha inhibitors are biologic drugs that treat autoimmune conditions, including HS. One study explored a few cases of paradoxical HS, which occurs when HS appears in people who use TNF-alpha inhibitors like adalimumab (Humira) and infliximab (Remicade), and etanercept (Enbrel). Paradoxical HS from TNF-alpha inhibitors is rare and tends to improve or go into remission when you stop using the drug.

Lithium, a medication prescribed to treat bipolar disorder, may be capable of triggering the development of HS in some people. Rarely, some oral contraceptives have also been associated with HS.

Risk Factor 8: Bacteria

While bacteria don’t directly cause HS, they can get stuck in clogged hair follicles to make HS flare-ups worse.

Health Conditions Related to Hidradenitis Suppurativa

People with certain health conditions are more likely to develop HS or vice versa. Health conditions that may be related to HS include:

• Inflammatory bowel disease (IBD), such as ulcerative colitis and Crohn’s disease
• Inflammatory joint diseases, such as rheumatoid arthritis, psoriatic arthritis, and spondylitis
• Pyoderma gangrenosum, a rare inflammatory skin condition involving leg ulcers
• Polycystic ovary syndrome
• Acne
• Psoriasis

More studies are needed to help researchers better understand the links between HS and these related conditions.

What Doesn’t Cause Hidradenitis Suppurativa?

There are many myths and misunderstandings about what causes HS. Scientific studies have proven that HS is not caused by:

• Poor hygiene
• Contagious disease
• Infection

HS isn’t contagious. However, some secondary skin infections may be contagious. It’s important to consult your dermatologist about any skin infections you may be experiencing.

Stress is not considered a possible cause of HS. However, it has been proven that stress is a common trigger that makes symptoms worse in those who have HS. Managing stress may help you avoid triggering HS flare-ups.

Is Hidradenitis Suppurativa Preventable?

Because dermatology researchers don’t yet fully understand what causes HS, there is no definite way to avoid getting the disease. Some risk factors, including genetics, are beyond anyone’s control.

If you’re concerned you may have a high risk for developing HS, focus on lowering that risk by changing the factors within your control. If you smoke, try to stop. Work toward better overall health with healthy eating, rest, and movement. If you have a condition believed to be related to HS, seek treatment to keep it under control. These changes may or may not help prevent HS, but they are likely to improve your overall well-being.

Consult your dermatologist to explore topical, oral, and surgical treatments for HS.

Talk With Others Who Understand

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

Are you living with hidradenitis suppurativa? Share your experience in the comments below, or start a conversation by posting on your Activities page.