What is Hidradenitis Suppurativa?

Hidradenitis Suppurativa (HS), also known in the European areas as Acne Inversa (AI), is a chronic, non-contagious, painful and quality of life impacting skin disease that causes boils to form in the folds of the skin and has a profound impact on quality of life1.  Many will experience a boil at some point in life.  However, there is a difference between an ordinary boil and HS.  It is important to understand the characteristics of HS/AI and to recognize the difference. There are 4 factors that could be considered when determining if boils are due to HS/AI.


  • Do you have boils that recur?
    • Boils caused by HS tend to recur in characteristic locations.


  • Do you have boils or scarring that appears in the characteristic locations of HS/AI?
    • The  axillae, under the breasts, under the folds of the stomach, groin, genital area, buttocks, and sometimes the nape of the neck and behind the ears are commonly affected by HS.


  •  Do you have boils that appear on both sides of the body?
    • HS usually affects both sides of the body and less commonly occurs on just one side.

Comorbidities (Associated Health Issues / Medical Conditions)

Recent research tells us there are certain common health conditions1 found in those with HS/AI, such as the following:

  • Metabolic Syndrome
  • Polycystic Ovarian Syndrome (PCOS)
  • Dissecting Cellulitis
  • Acne Conglobata
  • Diabetes
  • Inflammatory Bowel Diseases
  • Nicotine use
  • Spondyloarthrothopies
  • Heart Disease
  • Higher Body Mass Indices or BMI (although HS/AI can affect a person of any weight)

HS/AI is classified into 3 stages called Hurley Staging1.  Hurley Staging allows medical professionals to assign a severity level to HS/AI, but it does not account for disease activity, measure pain, or quality of life impact.

Hurley Staging

  • Hurley Stage I – is a single lesion without sinus tract (tunnel) formation.
  • Hurley Stage II – Stage II manifests as more than one lesion or area, but with limited tunneling.
  • Hurley Stage III – Stage III is defined as multiple lesions, with more extensive sinus tract formations and scarring. It involves an entire area of the body

Photo Courtesy of Henry Ford Hospital Follicular Disorders Clinic

hurley staging 1

What HS is Not

It is equally important to understand what HS/AI is NOT.


  1. Contagious – you cannot spread HS to another person through contact
  2. A Sexually Transmitted Disease (STD)
  3. MRSA, or a bacterial infection
  4. The result of poor hygiene
  5. HS/AI is NOT a rare disease

Recent research has allowed us to learn more about HS, but there is still a lot of work that needs to be done. While there is more information that has been learned about HS/AI in recent years, there is still much research that needs to be done. It is important for those with HS/AI and the medical community to work together to advance research, find better treatments and improve quality of life.

Rare Disease vs. Orphan Disease & Disease Prevalence

HS/AI have often been referred to as a rare disease, and/or orphan disease.  But what does this mean?

Although they have been used synonymously, there is a difference in the term of each word.

A rare disease is a distinction provided by the Center for Disease Control (CDC) to a disease that affects less than 200,000 persons.

However, an orphan disease is actually a classification used by the FDA in regard to drugs.

When a pharmaceutical company wishes to pursue market approval for a drug to treat a specific indication or disease, there are many lengthy steps that must be followed.  This is an arduous undertaking and can be especially difficult for diseases that are not very prevalent.

To assist in expediting the process of approval for a drug, the FDA can provide a classification of orphan status, which leads to accelerated approvals, tax incentives, and market exclusivity for a particular indication or disease.

HS/AI was once thought to be a rare disease.  However, in  peer –reviewed medical journals, it is widely accepted that HS/AI affects 1%-4% of the population, when all stages of the disease are considered1.  This means that there are millions of people living with HS/AI.

  • F1000Prime Rep. 2014 Dec 1;6:112. doi: 10.12703/P6-112. eCollection 2014. Update on hidradenitis suppurativa: connecting the tracts. Gill L, Williams M, Hamzavi I
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