Doctors and researchers used to think that hidradenitis suppurativa (HS), a chronic inflammatory skin condition, was rare. But that’s not accurate. Research now shows that it’s more common than previously thought. In fact, according to the Hidradenitis Suppurativa Foundation, between 1 percent and 2 percent of Americans have this skin disease. HS causes nodules (painful lumps) that can develop into abscesses that drain pus. These symptoms develop in areas of your body that rub together when you move, including your armpits, breasts, buttocks, and groin. It is also referred to as acne inversa.

Based on these statistics, roughly 1 in every 100 people has HS. However, some groups of people are more affected than others. In this article, we examine who is most likely to develop HS.

HS: Men vs. Women

Hidradenitis suppurativa affects people of all genders. But it impacts them in different ways.

In the United States, HS affects women three times as often as men, according to JAMA Dermatology. One of the reasons may be that hidradenitis suppurativa could be an autoimmune condition, a type of health problem where your immune system mistakenly attacks your organs or tissues. Up to 50 million Americans live with an autoimmune disease, and research from Stanford Medicine shows that women are far more likely to develop an autoimmune condition than men. One study from Stanford Medicine revealed that 4 out of 5 — 80 percent — of people living with an autoimmune disease are women.

Hormones may also affect HS, which could explain why more females have the condition than males, according to the American Academy of Dermatology. There is still a lot that isn’t known about how hormones affect HS. However, many people find that their symptoms are worse before they get their period, or improve while pregnant or after menopause.

However, while men experience fewer cases of HS, they are more likely to experience severe signs and symptoms. Their skin problems also show up in unusual locations. For example, more men than women develop HS on their face, neck, and scalp, according to the International Journal of Women’s Dermatology.

HS, Race, and Ethnicity

Although research into the relationship between race, ethnicity, and HS is limited, your ethnic background does appear to play a role in your chances of developing hidradenitis suppurativa.

HS impacts Black and biracial people the most, according to the Journal of the American Academy of Dermatology. Black and biracial people develop the condition at nearly three times the rate of white people, according to JAMA Dermatology. Unfortunately, there isn’t enough research about HS and Hispanic or Asian people to know how many people within this population it affects. Still, according to some research published in Cureus, Hispanic people, like Black people, experience more severe cases of this skin condition.

Being more likely to develop HS is only part of the problem for people in racial and ethnic minority groups, however. It typically takes longer for them to get an accurate diagnosis and they report higher pain levels and a greater impact on their daily activities, according to the Journal of Dermatology. In addition, Black people with HS have a 15 to 20 times higher risk for developing visible scars that linger than people with lighter skin.

HS and Age

Although the risk for many health conditions increases with age, the opposite is true for hidradenitis suppurativa. For most people, the first signs of HS show up soon after puberty — sometime between the late teens and early 20s. In fact, up to 50 percent of people see the first signs between ages 10 and 21. Unfortunately, the appearance of symptoms at an earlier age doesn’t always mean doctors will recognize the condition. Some research shows that when signs like acne appear on the breasts and thighs, people may not receive an accurate diagnosis for years.

It isn’t uncommon for people to develop hidradenitis suppurativa in middle age. If this happens to you, it may mean you’ll develop a more severe case of the disease. Research published in the Journal of the American Academy of Dermatology shows signs that appear after age 40 are usually more significant, especially for women.

Little research has been done into how frequently HS affects older adults. But that’s starting to change. Early investigations show the skin condition is more common in this age group than doctors previously believed. And, unlike hidradenitis suppurativa that shows up earlier in life, HS that appears at a later age is more likely to affect men, according to the British Journal of Dermatology.

HS and Other Risk Factors

In addition to your sex, race, and age, a few other factors may impact your chances of developing hidradenitis suppurativa. You can change some of these risk factors, but others are out of your control.

Diabetes

Diabetes and HS have one big factor in common — they both link to chronic inflammation and insulin resistance. That means they frequently appear together. Several studies show that nearly 25 percent of people with HS also have diabetes.

Family History

While there’s still a lot to learn about the genetics behind hidradenitis suppurativa, researchers believe you can inherit it. Some studies show that roughly 40 percent of people with HS have a family history of the condition. Other investigations say the incidence is even higher. In one study, 57.5 percent of people with HS reported having a first- or second-degree relative who also has the condition.

Obesity

Obesity is defined as a body mass index score of 30 or higher. In one study, a research group examined the rate of HS in children and adolescents. They determined that 68.7 percent of children with HS had body weights classified as obese. By comparison, 29.8 percent of children without HS had body weights classified as obese.

Smoking

Smoking is one of the lifestyle behaviors that has the biggest impact on hidradenitis suppurativa. Existing research shows that people who smoke experience HS at nearly four times the rate as those who don’t. People who smoke typically have more body parts affected by HS. Tobacco also interferes with how well the condition responds to treatment. Giving up smoking can lower your risk of HS.

Talk With Others Who Understand

On myHSteam, the social network for people with hidradenitis suppurativa and their loved ones, more than 46,000 members come together to ask questions, give advice, and share their stories with others who understand life with HS.

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