HS stands for hidradenitis suppurativa, a chronic inflammatory skin condition that causes painful lumps, abscesses, and tunnels beneath the skin. It typically develops in areas where skin rubs together, like the armpits, groin, buttocks, and under the breasts. HS affects people most often in their 20s and 30s, and despite having straightforward diagnostic criteria, it takes an average of 7 to 10 years from the first symptoms for most people to get a correct diagnosis.
What Causes HS
HS begins with blocked hair follicles. The follicle becomes clogged, swells, and eventually ruptures beneath the skin’s surface. When that happens, the contents of the follicle, including keratin and bacteria, spill into the surrounding tissue. The immune system responds aggressively, sending waves of inflammatory cells to the area, which leads to abscess formation and destruction of the hair follicle and nearby structures.
This isn’t a hygiene issue or a simple infection. HS is fundamentally a disease of the immune system combined with a defect in how the skin clears material from hair follicles. The inflammation tends to recur in the same areas, and over time it can create scar tissue and tunnels (called sinus tracts) that connect abscesses beneath the skin.
What HS Looks and Feels Like
The experience of HS varies widely depending on severity. Dermatologists use the Hurley staging system to classify it into three levels:
- Stage I: One or more abscesses without sinus tracts or scarring. This is the mildest form and may look like recurring boils.
- Stage II: Recurrent abscesses with sinus tracts and scarring, but separated by areas of normal skin.
- Stage III: Diffuse involvement with multiple interconnected sinus tracts and abscesses across an entire area. This is the most severe and debilitating form.
The lumps are often deep, tender, and can drain foul-smelling fluid. Flares may last days to weeks, and the pain can be significant enough to interfere with work, movement, and daily activities. HS is consistently ranked as one of the most life-impacting skin disorders, affecting professional, social, and sexual quality of life.
Why It Takes So Long to Diagnose
One of the most frustrating aspects of HS is the diagnostic delay. A 2024 study of 285 patients found the mean delay was 10.1 years, and that gap has not improved over time. Early HS lesions look a lot like common conditions: boils, deep acne, infected cysts, or even Crohn’s disease affecting the skin. Many people cycle through emergency rooms or primary care offices getting treated for individual abscesses without anyone recognizing the pattern. The diagnosis is clinical, meaning it’s based on the appearance and location of lesions, their recurrence, and the presence of scarring or tunneling rather than on any single lab test or biopsy.
Risk Factors and Related Conditions
Smoking and obesity are the two most consistently linked modifiable risk factors. Nonsmokers show about an 11% higher rate of disease remission compared to current smokers, and quitting is associated with fewer new lesions after surgery. While reducing the number of cigarettes hasn’t been shown to directly lower HS risk, quitting entirely appears to improve outcomes.
HS also clusters with several other conditions. Women with HS are roughly twice as likely to have polycystic ovary syndrome (PCOS) compared to women without HS (8.8% vs. 4.3% in one large study). Both conditions involve hormonal imbalances and chronic low-grade inflammation, and excess body fat may amplify the inflammatory signals that drive both diseases. Metabolic syndrome, diabetes, and depression are also more common in people living with HS.
How HS Is Treated
Treatment depends on severity and ranges from topical medications to surgery. For mild to moderate disease, a topical antibiotic solution applied directly to the skin can reduce the number of pustules, though it doesn’t do much for deeper nodules and abscesses. Oral antibiotics taken for 12-week courses are another early option and have been shown to reduce abscesses by about 30%. These antibiotics work partly through their anti-inflammatory properties, not just by fighting bacteria.
For moderate to severe HS, two biologic medications are currently FDA-approved. The first, approved in 2015, targets a specific inflammatory protein called TNF-alpha. The second, approved in 2023, works on a different inflammatory pathway called IL-17A. Both are reserved for people with a minimum number of active abscesses and inflammatory nodules, typically three to five combined.
Surgical Options
When medications aren’t enough, surgery plays an important role. Two main approaches exist. Unroofing (also called deroofing) is a less invasive procedure done in an outpatient setting where the roof of a sinus tract is removed, allowing the area to heal from the bottom up. Wide excision is a more extensive surgery typically reserved for Stage III disease, where large areas of affected tissue are removed entirely.
Counterintuitively, the less invasive approach has better recurrence numbers. About 15% of patients who underwent unroofing experienced recurrence compared to 30% of those who had excision. At the individual lesion level, the pattern held: 20% of unroofed lesions recurred versus 26% of excised ones. This may reflect differences in the types of patients and disease severity selected for each procedure, but it underscores that more aggressive surgery doesn’t always mean better long-term results.
Living With HS
HS is a lifelong condition for most people, though flares can become less frequent with effective treatment and lifestyle changes. Weight loss reduces mechanical friction and lowers the inflammatory burden from excess fat tissue. Quitting smoking improves the odds of remission and reduces new lesion formation after surgery. Loose-fitting clothing and gentle skin care in affected areas can help minimize irritation during flares.
Because HS overlaps with so many other conditions and carries such a long diagnostic delay, getting the right diagnosis is itself a turning point. If you’ve been dealing with recurring painful lumps in your armpits, groin, or buttocks that keep coming back in the same spots, that pattern is the hallmark of HS, and naming it opens the door to treatments that go far beyond draining individual abscesses.