Hidradenitis suppurativa (HS) affects roughly 1% of the global population, making it more common than many people realize. A 2024 meta-analysis published in JAMA Dermatology, drawing from over 22,000 participants across 23 countries, estimated the global prevalence at 0.99%, with a range between 0.67% and 1.46%. That figure surpasses older estimates, which often placed HS below 1%.
Despite how many people it affects, HS remains widely underdiagnosed. Most patients wait 7 to 10 years from their first symptoms before receiving a correct diagnosis, and some wait over 20 years. The condition is diagnosed based on appearance and pattern alone: recurring painful nodules, tunnels under the skin, and scarring in areas like the armpits, groin, and under the breasts.
Who Gets HS Most Often
HS does not affect all groups equally. In the United States, African Americans have the highest prevalence at about 1.3%, compared to 0.75% in white populations and 0.07% in Hispanic/Latino populations. These differences have raised questions about genetic factors, though the full picture is still being studied.
Gender patterns vary by region. In Europe and North America, women outnumber men with HS at roughly a 3:1 ratio. In Asian populations, that pattern reverses, with men affected about twice as often as women. The JAMA Dermatology meta-analysis confirmed that a higher proportion of female participants in a study population was associated with higher prevalence estimates overall.
Typical Age of Onset
HS follows a bimodal pattern, meaning it has two distinct peaks of onset. About 79% of cases begin in the mid-to-late teen years, which is the more common trajectory. The remaining 21% develop symptoms later, typically in the mid-40s. For the late-onset group, the average age is around 43.5 years in women and 45.2 years in men.
Children can develop HS, but it’s rare. The overall prevalence in people under 18 is approximately 0.03%. It becomes more common as adolescents get older: 0.002% in children younger than 9, 0.03% in the 10 to 14 age group, and 0.11% in those aged 15 to 17. That steep climb during puberty aligns with the hormonal changes thought to play a role in triggering the condition.
Risk Factors That Increase Your Chances
Smoking and obesity are the two most prominent modifiable risk factors for HS. Studies have found smoking rates of 70% to 90% among people with the condition, far higher than in the general population. Obesity prevalence among HS patients ranges widely across studies, from about 6% to 73%, but consistently exceeds rates in matched control groups. Both factors are believed to worsen inflammation and mechanical friction in skin folds, which can trigger or intensify flares.
Family history is another strong predictor. In a study of 676 HS patients at the University of North Carolina, 57.5% reported having a first- or second-degree relative with the condition. Nearly half, 49.5%, had an affected first-degree relative like a parent or sibling. This suggests a significant genetic component, though no single gene has been identified as the primary driver in most cases.
How Severity Breaks Down
HS is classified into three stages based on the extent of disease. Stage I, the mildest form, involves isolated lumps without sinus tracts or scarring and accounts for about 45.5% of diagnosed patients. Stage II, with recurrent lumps and some tunnel formation, makes up 41.5%. Stage III, the most severe form involving widespread interconnected tunnels and scarring across an entire area, affects about 13% of patients. Research shows that Stage III follows a notably more aggressive course, which is why early recognition matters.
Why So Many Cases Go Undiagnosed
The gap between how common HS actually is and how often it gets diagnosed is significant. There is no blood test or biopsy required. Doctors diagnose it by recognizing the pattern: recurring nodules in characteristic locations that persist over time. Yet the average delay from first symptoms to diagnosis is 7 to 10 years, with one large real-world study finding a mean delay of about 38 months even in a clinical setting with awareness of the condition.
Several factors contribute to this delay. Early HS lesions are frequently mistaken for boils, ingrown hairs, or simple skin infections. Many patients feel embarrassed about symptoms in intimate areas and avoid seeking care. When they do see a doctor, they may be treated with antibiotics for a presumed infection rather than evaluated for a chronic inflammatory condition. Because HS tends to flare and temporarily resolve, both patients and clinicians can underestimate its significance in the early stages.
The combination of high prevalence and long diagnostic delays means a substantial number of people are living with HS without knowing it has a name, let alone that treatments exist. If you experience recurring painful bumps in your armpits, groin, or under the breasts that keep coming back in the same areas, that pattern itself is the key diagnostic clue.