What Is Hidradenitis Suppurativa (HS)?

When it comes to hidradenitis suppurativa (HS), a chronic condition marked by painful lumps under the skin, it’s more than just clogged pores.

HS is caused by inflammation of the sweat glands, which blocks and inflames the hair follicles, says Erum Ilyas, MD, Dermatologist at Montgomery Dermatology in Pennsylvania. This creates tender, painful lumps and nodules under the skin.

“There's a lot of inflammation under the skin that can be very uncomfortable,” Ilyas explains.

What causes HS symptoms?

When a person develops HS, the hair follicle is blocked and inflamed by a protein called keratin. The follicle swells and fills up with fluid and forms a tender, painful nodule. 

Sometimes pus may start to drain from the surface of the skin, creating a painful sore. These sores can give off a foul odor, and can also make it difficult to move. That’s because the sores usually arise in areas where the skin folds, such as in or under the:

• Armpits

• Buttocks

• Breasts

• Inner thighs

• Groin

“They can actually affect your mobility or movement, because they’re in those areas of the skin where the skin folds together,” she says.

What are the risk factors for HS?

The exact cause of HS is unknown, but researchers have noticed a few factors.

HS usually starts after puberty or during young adulthood, and symptoms may change based on menstrual cycles, pregnancy, and menopause. For this reason, hormones are believed to play a role. 

HS also tends to run in families, so there may be a genetic component. It’s more common in women, people who smoke cigarettes, and people who are overweight or have psoriasis. HS also more commonly occurs in Black, Hispanic, or biracial people, compared to white people.

The good news is that HS is not contagious. Rather, it’s an inflammatory reaction to the presence of bacteria in the skin, according to Ilyas.

“There's not a one size fits all approach to HS,” she adds. “Knowing that we have so many great tools at our disposal is the most important thing to remember.”