Hidradenitis Suppurativa: Causes, Stages, and Treatment

What hidradenitis suppurativa actually is and where it starts

Hidradenitis suppurativa is a chronic inflammatory skin disease that begins when hair follicles become blocked with keratin and cellular debris. This blockage occurs primarily in areas with apocrine glands (armpits, groin, under breasts, buttocks). When the follicle ruptures, its contents spill into surrounding tissue, triggering an intense immune response. This creates painful nodules, abscesses, and eventually sinus tracts that tunnel under the skin and drain intermittently. Over time, repeated cycles of inflammation lead to fibrosis and permanent scarring.

How the immune system drives hidradenitis suppurativa

The immune response in HS is disproportionate to the initial follicular rupture. Rather than resolving quickly, inflammation becomes chronic and self-perpetuating. Elevated levels of pro-inflammatory cytokines (TNF-alpha, IL-1beta, IL-17) drive tissue destruction and inhibit normal wound healing. This pattern resembles hidradenitis suppurativa autoimmune conditions, where the immune system attacks the body's own tissues. Some studies suggest that HS may represent a subtype of autoinflammatory keratinization disease, where the skin barrier and immune system are both intrinsically dysregulated.

The gut-skin axis in HS

Patients with HS often show altered gut microbiome composition compared to healthy controls, with reduced microbial diversity and shifts in bacterial populations. This matters because the gut microbiome modulates systemic inflammation. When intestinal permeability increases, bacterial endotoxins can enter circulation and activate immune pathways that worsen skin inflammation. The association between HS and inflammatory bowel disease further supports this connection.

Hormonal drivers

HS typically emerges after puberty and worsens with menstrual cycles, suggesting androgen involvement. Elevated androgens increase sebum production and alter follicular keratinization, making blockage more likely. Insulin resistance amplifies androgen effects by reducing sex hormone binding globulin (SHBG), which increases free testosterone levels. This explains why HS severity often correlates with metabolic dysfunction.

What triggers flares and determines severity

HS is a chronic condition with a relapsing-remitting pattern. Understanding what drives flares helps distinguish between baseline disease activity and acute worsening.

Friction and occlusion

Tight clothing, heat, and sweating increase friction in skin folds, which mechanically stresses hair follicles and promotes blockage. This is why HS lesions cluster in areas where skin rubs against skin or fabric.

Smoking

Nicotine stimulates keratinocyte proliferation and alters immune cell function, both of which worsen follicular occlusion and inflammatory response. Over 80% of HS patients are current or former smokers, and smoking cessation is associated with reduced disease severity.

Obesity and metabolic dysfunction

Adipose tissue secretes pro-inflammatory cytokines (adipokines) that amplify systemic inflammation. Increased skin fold depth creates more occlusive environments where follicles are prone to blockage. Insulin resistance, common in obesity, further drives androgen excess and inflammatory signaling.

Diet and gut health

High glycemic load diets and dairy consumption have been anecdotally linked to HS flares, though direct mechanistic evidence is limited. What's clearer is that gut microbiome composition affects systemic inflammatory tone. Diets that promote gut dysbiosis (those high in processed foods and low in fiber) may indirectly worsen HS.

Stress and the HPA axis

Psychological stress activates the hypothalamic-pituitary-adrenal (HPA) axis, increasing cortisol and catecholamines. Chronic stress impairs skin barrier function, alters immune response, and can trigger mast cell degranulation, all of which may contribute to HS flares.

Why the same condition looks different in different people

HS severity and presentation vary widely. Some patients experience isolated nodules that resolve with minimal scarring. Others develop extensive sinus tracts, chronic drainage, and disfiguring scars. This variation reflects genetic, immunologic, and environmental differences.

Genetics

Approximately one-third of HS patients have a family history of the condition. Mutations in genes encoding gamma-secretase (NCSTN, PSENEN, PSEN1) have been identified in familial cases. These mutations affect Notch signaling, which regulates follicular differentiation and immune response. Genetic variation also influences cytokine production and inflammatory response patterns.

Skin microbiome composition

The skin microbiome in HS lesions differs from healthy skin. There's often an overgrowth of Gram-negative anaerobes and a reduction in protective Cutibacterium species. Individual variation in baseline microbiome composition affects how the skin responds to follicular rupture and whether secondary infection occurs.

Immune phenotype

Some patients have a Th1-dominant immune response, others Th17-dominant. This affects which cytokines drive inflammation and which treatments are most effective. Variation in mast cell reactivity and IgE-mediated responses also influences symptom severity.

Presentation in skin of color

Hidradenitis suppurativa black skin presentations involve higher disease prevalence, earlier onset, and more severe scarring outcomes. Black patients are four times more likely to report severe HS-related pain compared to non-Black patients (Udechukwu et al., 2021). On darker skin tones, early lesions may appear as hyperpigmented nodules rather than red bumps, which can delay diagnosis. Scarring is often more prominent and may present as thickened, darkened plaques.

When skin symptoms point to something systemic

Persistent or treatment-resistant HS warrants investigation beyond the skin. The condition is associated with several systemic health risks:

• HS patients have higher rates of obesity, insulin resistance, dyslipidemia, and hypertension due to shared inflammatory pathways.
• Chronic inflammation in HS is linked to increased cardiovascular disease risk through elevated inflammatory markers like hsCRP and IL-6.
• HS and IBD co-occur more often than expected by chance, both involving dysregulated immune responses and gut microbiome alterations.
• HS patients have higher rates of thyroid autoimmunity, psoriasis, lupus, and rheumatoid arthritis.

Tracking hsCRP, fasting insulin, HbA1c, and lipid panels can help identify metabolic dysfunction early. If HS patients develop gastrointestinal symptoms like chronic diarrhea, abdominal pain, or blood in stool, IBD should be considered. When HS is accompanied by joint pain, fatigue, or other systemic symptoms, testing for TPO antibodies, ANA, rheumatoid factor, and anti-CCP antibodies can surface underlying autoimmune drivers.

What biomarkers can tell you when topicals aren't enough

When hidradenitis suppurativa home treatment approaches like warm compresses, antiseptic washes, and loose clothing aren't controlling symptoms, it's time to look deeper. HS that persists despite topical management often has systemic drivers that biomarker testing can help identify.

For patients with suspected hormonal triggers, testing total testosterone, free testosterone, DHEA-S, SHBG, and fasting insulin can reveal androgen excess or insulin resistance. For those with suspected gut involvement, a comprehensive gut microbiome panel can show dysbiosis patterns linked to systemic inflammation. Inflammatory markers like hsCRP, ESR, and ferritin help assess baseline inflammatory load. Nutrient deficiencies, particularly vitamin D and zinc, are common in chronic inflammatory conditions and worth checking.

Tracking these markers over time, not just reacting to individual flares, gives you a clearer picture of what's driving the condition at a systemic level.

Getting to the root of what's driving your skin

If your HS keeps coming back despite doing everything right at the surface level, the answer isn't another topical. Superpower's 100+ biomarker panel can show you what's happening hormonally, metabolically, and immunologically so your next step is based on data, not guesswork. Persistent skin inflammation is a signal. Superpower helps you read it at a systemic level, not just treat it at the surface.