60-second summary
If you only remember four things, remember these:
- The European S2k guideline for HS/acne inversa (Part 1, 2026) updates the predecessor guideline from 2015, substantially expanding diagnosis, severity assessment and comorbidities.
- Six changes directly affect patients: severity scoring, comorbidity screening, heart health, the definition of a flare, care for teenagers, and what matters beyond lesion count.
- This article briefly orients each change and links to the detailed article on it.
- None of these points replaces an individual clinical assessment.
You don't need to read the guideline yourself to benefit from it — this overview and the linked articles translate the relevant parts into something you can actually use at your next appointment.
This overview focuses on the points with the most immediate relevance to patients and is not a complete summary of the entire guideline.
Pick whichever point below matches your current situation and read the linked article for it.
This summary is written and updated together with the full text. The evidence, limitations and sources stay unchanged in the article below.
Continue to the detailed explanationIn August 2026, the European Hidradenitis Suppurativa Foundation published the first part of a new guideline for HS (acne inversa) — a substantial update to the predecessor guideline from 2015. According to PubMed, the authors describe the expansion themselves this way: “The expansion of the guideline is evident and signifies a major leap forward in HS management” (DOI).
The biggest change isn’t a single new test. It’s a considerably broader view of what a good HS assessment should include — beyond lesion count alone.
This article summarizes six changes with direct relevance to patients, and links to the detailed article on each one. It’s deliberately not a full guideline excerpt — it’s an orientation for where to read further if a point matches your situation.
For information only. This overview explains a guideline update for patients. It does not diagnose anything and does not replace an individual clinical assessment.
01 — Hurley stage alone is no longer enough
Classic Hurley stagingHurley Stage: A regional, mainly structural classification system for Acne Inversa in one specific body region, in three stages: Stage I (single abscesses without sinus tracts), Stage II (recurrent abscesses with isolated, still-separated sinus tracts), Stage III (extensive, interconnected sinus tracts and scarring across an entire region). Named after Dr. Helen Hurley. Classic Hurley staging is static and isn't designed to reflect short-term inflammatory activity or response to medical treatment — IHS4 is used alongside it for that. describes structural changes (tunnelsSinus Tract: A tunnel-like channel under the skin that forms between abscesses or nodules. Sinus tracts indicate more advanced disease and can chronically drain fluid. They are associated with Hurley Stages II and III., scarring) in one body region — but not current inflammatory activity. The guideline update additionally recommends the IHS4 scoreIHS4 Score: A validated, dynamic tool for measuring current inflammatory disease activity in Acne Inversa (unlike the mainly structural, static Hurley stage). The score is calculated from the number of inflammatory nodules, plus 2 points per abscess, plus 4 points per draining sinus tract; scores up to 3 are mild, 4–10 moderate, 11 or more severe. This allows objective tracking of treatment response over time., which counts nodulesNodule: A firm, palpable lump deep in tissue. Nodules can be painful and may progress to abscesses. They are among the typical early signs of Acne Inversa., abscessesAbscess: An inflamed cavity or swelling containing pus or fluid. In hidradenitis suppurativa, abscesses can form as part of the inflammatory disease process and do not automatically mean that a bacterial infection is present. Secondary bacterial infection can occur and may require separate medical assessment. In Acne Inversa, abscesses occur mainly in the armpits, groin, and other skin folds. and draining tunnelsDraining Tunnel: A sinus tract or fistula actively leaking fluid (serous, purulent, or blood-tinged) to the surface. Draining tunnels carry the heaviest weight in modern HS severity scores because they signal long-standing, structurally damaged disease., because classic Hurley is too static for tracking treatment response. → Hurley Stages vs IHS4: What Your HS Severity Score Actually Means
02 — HS is more than a skin disease
The new guideline assigns several comorbidityComorbidity: An additional condition existing alongside the primary disease. Acne Inversa is frequently associated with comorbidities including metabolic syndrome, inflammatory bowel disease, spondyloarthritis, and depression. areas — including mental health, cardiovascular risk, diabetes/metabolic health, joints, gut, and psoriasis — an explicit recommendation about assessment timing for the first time, rather than just naming them as associations. → HS Beyond the Skin: What Health Checks Should You Discuss With Your Doctor?
03 — Heart health deserves a recurring check
Within that broader comorbidity framework, cardiovascular risk gets an especially concrete recommendation: assessment at the first visit and then at least annually. → HS and Heart Health: Why the New European Guideline Recommends Cardiovascular Checks
04 — A flare now has a shared working definition
“FlareFlare: A period of acute worsening in a chronic condition. In Acne Inversa, a flare may be triggered by stress, hormonal changes, friction, or other factors and can manifest as new nodules, abscesses, or increased pain.” has been used very inconsistently in HS research for years. The new guideline sets out a working definition for the first time: a new or substantial worsening of signs or symptoms. → What Actually Counts as an HS Flare?
05 — Teenagers need their own diagnostic attention
The guideline devotes a dedicated section to children and adolescents for the first time. HS can start during puberty and is often recognised later in this age group than in adults — not because it’s rarer, but because it’s more easily mistaken for ordinary puberty skin. → HS in Teenagers: Can Hidradenitis Suppurativa Start During Puberty?
06 — Your severity score isn’t your whole disease
Beyond any single score, the guideline explicitly refers to a broader, internationally agreed framework: six domains that together give a fuller picture than any single number — pain, physical signs, quality of life, global assessment, disease course, and symptoms beyond pain. → Your HS Is More Than a Lesion Count
What these six points have in common
Each of these points makes the same underlying claim in its own way: a single number, a single test, or a single lesion only partially describes your disease. The new guideline gathers that into a considerably broader, multidimensional framework — severity, comorbidities, disease course, patient experience — instead of leaving it at a lesion count.
In practice, that means an appointment focused entirely on lesions or a single score doesn’t automatically cover everything that matters about your disease. The articles linked above give you concrete wording to raise what otherwise easily gets missed.
The bottom line
The new European S2k guideline is no substitute for your individual care, but it describes how good HS assessment has changed in 2026: broader, more multidimensional, and more explicit about what matters beyond the skin. Pick whichever of the six points above matches your current situation, and bring it to your next appointment.
Terms explained in this article
Quick definitions of the key medical terms. Select any term for its full glossary entry.
- Hurley Stage
- A regional, mainly structural classification system for Acne Inversa in one specific body region, in three stages: Stage I (single abscesses without sinus tracts), Stage II (recurrent abscesses with isolated, still-separated sinus tracts), Stage III (extensive, interconnected sinus tracts and scarring across an entire region). Named after Dr. Helen Hurley. Classic Hurley staging is static and isn't designed to reflect short-term inflammatory activity or response to medical treatment — IHS4 is used alongside it for that.
- Sinus Tract
- A tunnel-like channel under the skin that forms between abscesses or nodules. Sinus tracts indicate more advanced disease and can chronically drain fluid. They are associated with Hurley Stages II and III.
- IHS4 Score
- A validated, dynamic tool for measuring current inflammatory disease activity in Acne Inversa (unlike the mainly structural, static Hurley stage). The score is calculated from the number of inflammatory nodules, plus 2 points per abscess, plus 4 points per draining sinus tract; scores up to 3 are mild, 4–10 moderate, 11 or more severe. This allows objective tracking of treatment response over time.
- Nodule
- A firm, palpable lump deep in tissue. Nodules can be painful and may progress to abscesses. They are among the typical early signs of Acne Inversa.
- Abscess
- An inflamed cavity or swelling containing pus or fluid. In hidradenitis suppurativa, abscesses can form as part of the inflammatory disease process and do not automatically mean that a bacterial infection is present. Secondary bacterial infection can occur and may require separate medical assessment. In Acne Inversa, abscesses occur mainly in the armpits, groin, and other skin folds.
- Draining Tunnel
- A sinus tract or fistula actively leaking fluid (serous, purulent, or blood-tinged) to the surface. Draining tunnels carry the heaviest weight in modern HS severity scores because they signal long-standing, structurally damaged disease.
- Comorbidity
- An additional condition existing alongside the primary disease. Acne Inversa is frequently associated with comorbidities including metabolic syndrome, inflammatory bowel disease, spondyloarthritis, and depression.
- Flare
- A period of acute worsening in a chronic condition. In Acne Inversa, a flare may be triggered by stress, hormonal changes, friction, or other factors and can manifest as new nodules, abscesses, or increased pain.
FAQ
What's the difference between the 2015 S1 guideline and the new S2k guideline?
Both are guidelines from the European Hidradenitis Suppurativa Foundation. The 2015 S1 level rested on a simpler expert consensus; the new S2k level (Part 1, 2026) rests on a structured consensus from a larger expert panel via a Delphi process, with substantially expanded chapters on diagnosis, severity assessment and comorbidities. The authors themselves describe the expansion as a significant step forward from 2015.
Do I need to read the guideline myself?
No. Guidelines like this are written primarily for clinicians and are correspondingly technical. This overview and the linked articles translate the parts with direct relevance to patients into a more accessible form, while pointing to the original source for anyone who wants to read it anyway.
Does this guideline change my treatment immediately?
Not automatically. Guidelines like this are aimed at clinicians and provide consensus-based orientation — how quickly and in what form that shows up in your individual care is decided by your clinician. This overview can help you raise the topic specifically, but it doesn't make a treatment decision for you.
Does this article cover everything in the new guideline?
No, deliberately not. The guideline covers many further topics for clinicians, including detailed diagnostic criteria, imaging procedures, and a full account of epidemiology. This overview deliberately focuses on the points with the most immediate practical relevance to patients.
References
- Jemec GBE, Villumsen B, van Straalen KR, et al. European S2k guidelines for hidradenitis suppurativa/acne inversa Part 1. Epidemiology, diagnosis and clinical assessment. Journal of the European Academy of Dermatology and Venereology, 2026
- Zouboulis CC, Desai N, Emtestam L, et al. European S1 guideline for the treatment of hidradenitis suppurativa/acne inversa. Journal of the European Academy of Dermatology and Venereology, 2015
