Understanding Hidradenitis Suppurativa

What is Hidradenitis Suppurativa (HS)?

Hidradenitis Suppurativa (HS) is a chronic, inflammatory skin disease characterized by painful nodules and abscesses which form most commonly in sensitive areas: under arms and breasts, along buttocks and groin, though HS may appear anywhere there is hair.

When symptoms first appear, they appear as painful, recurrent pimples or cysts in telltale areas. Because of its appearance and location, HS is often misdiagnosed as ingrown hairs, folliculitis, staph infection, cellulitis, or an STD. But unlike those conditions, HS cannot be cured and the lesions left behind will often refill, have difficulty healing, and leave behind scars.

Women are diagnosed with HS 3x more often than men and their symptoms tend to start around puberty or other times of hormonal changes like pregnancy, postpartum, or changes in hormonal birth control.

How Is Hidradenitis Suppurativa Diagnosed?

Hidradenitis Suppurativa (HS) is a clinical diagnosis, which means that a doctor cannot run a test to determine if you have HS.   A doctor will look for these signs and symptoms to determine if it is HS or a different, similar-presenting condition.

  • Have you had painful, swollen bumps that may look like boils or large pimples on your chest, underarms, groin, buttocks, or thighs?
  • Did those bumps reappear in those areas 3 or more times?
  • Did these bumps leave behind scars?
  • Do the bumps appear symmetrically – for example under both arms, or on both thighs?
  • In the same area where you get these bumps, do you also get comedones (blackheads)?

While diagnosing HS, doctors may also swab the affected area to rule out bacterial infection.  As a specialist in skin conditions, a dermatologist would be most familiar with the signs and symptoms of HS.

How many people have Hidradenitis Suppurativa?

HS typically goes undiagnosed for years because patients are ashamed to speak with anyone. When they do see a doctor, the disease is frequently misdiagnosed.  It is reported that patients visit, on average, 15 doctors over 7 years before achieving the correct diagnosis.

Historically, HS has been considered a rare disorder, because it is difficult to accurately estimate the number of people living with HS; they conceal their condition, even from friends and close relatives. However, when all stages of the disease are considered, it is estimated that 1-4% of the population – potentially up to 13 million Americans alone – have Hidradenitis Suppurativa.

How is Hidradenitis Suppurativa severity measured?

Hidradenitis Suppurativa typically develops slowly over time.  Development differs, however, from individual to individual.  Most patients with HS (an estimated 2/3rds) will never develop past a mild stage.  With others, it may escalate and become a debilitating disease.   It is not known why.

The severity of an individual’s HS is measured by stages. The most commonly used staging system is “Hurley”, which was developed by Dr. H J Hurley, a dermatologist and surgeon. Other stages that more accurately measure activity may also be used.

Note: Patients can be in multiple stages in different areas of their body.

Hurley stages are:

  • Stage 1 (“Mild”): Solitary or multiple isolated abscess formation without sinus tracts (“tunnels”)
  • Stage 2 (“Moderate”): Recurrent abscesses, single or multiple widely separated lesions, with beginning sinus tract (tunnel) formation
  • Stage 3 (“Severe”): Diffuse or broad involvement across a regional area with multiple interconnected sinus tracts (tunnels), significant scarring and persistent abscesses.
What causes Hidradenitis Suppurativa?

Doctors are still unsure of the causes of HS, but a malfunctioning immune system, genetics, hormones, unique anatomy of hair follicles, skin microbiome, and environmental triggers are all considered factors for HS.

What are myths and misunderstandings about Hidradenitis Suppurativa?

Hidradenitis Suppurativa is NOT contagious.  The lesions and spots may resemble conditions which people associate with being contagious, but HS is not contagious.

Hidradenitis Suppurativa is NOT acne.  When the symptoms of HS first appear, some people may think that they have a form of severe below-the-belt acne.  Compounding this confusion is that in some parts of the world, HS is referred to as “acne inversa.”  Some treatments for HS are used in acne, but that is where the similarities end.

Hidradenitis Suppurativa is NOT caused by poor hygeine.  HS may resemble conditions like furuncles or boils to the untrained eye, but bathing routines do not cause nor cure HS.  Individuals living with HS grapple with the fear of stigmatization every day, and the misconception that HS is associated with poor hygiene is among the biggest myths.

Hidradenitis Suppurativa is NOT an STD.  Because HS can often appear in the groin area, people are often concerned that their partners may think they have a sexually transmitted disease.  And while the causes of HS are not yet fully understood, it is very clearly NOT an STD nor is it contagious.

Hidradenitis Suppurativa is NOT caused by smoking and being overweight.  No one disputes that smoking or excess weight is bad for long-term health.  But HS doesn’t begin with weight and smoking, nor is it cured by ending smoking or losing weight.  Patients are diagnosed at every stage in every body type.  Many patients have no history of smoking.  Studies show a correlation between smoking and obesity with HS, but they have not shown a causative link, nor have they demonstrated that weight loss or smoking cessation will improve one’s HS.  Patients report daily that smoking cessation or weight loss makes their condition worse, but this poor advice continues to be offered to patients as a fix for all of their HS symptoms.

Pain from HS affects a patient’s mobility and energy levels, making it harder to be active.  Doctors must first help treat the HS before a patient can undertake exercise or lifestyle changes.

Does having Hidradenitis Suppurativa make one more likely to develop other conditions?


A complication is an undesired, sometimes dangerous, evolution or consequence of disease progression.  In HS, the most noteworthy complications are a result of living with chronic, open wounds.

Cellulitis – Cellulitis is a bacterial infection of the skin.  Although HS is not caused primarily by bacteria, all humans carry normal skin bacteria on their skin and having open wounds (especially squeezing or touching these areas) introduces the opportunity for bacteria to enter the skin where it doesn’t belong, potentially causing cellulitis.

Symptoms of cellulitis are easy to confuse with the symptoms of an HS flare, which include swelling, redness, pain, and warmth of the affected area.  If you suspect that your HS has evolved to cellulitis, you can aid observation by tracing the area with a marker and observing if the redness spreads, as cellulitis will spread faster than an HS flare.  Additional symptoms that indicate medical treatment beyond HS treatment is necessary include a fever, nausea, and malaise if these symptoms do not usually accompany your HS flares.

The best way to prevent cellulitis is to never squeeze your HS nodules, do not self-lance, practice good wound care, and only tend to your wounds with thoroughly clean hands.

Sepsis –  Sepsis is a life-threatening condition that arises when the body’s response to infection causes injury to its own tissues and organs.  In addition to symptoms related to HS and cellulitis, sepsis is frequently associated with fever, rapid breathing and heart rate, confusion, swelling, and low body temperature.

If you suspect sepsis or cellulitis, proceed to an emergency department.  Cellulitis and Sepsis cannot be self-treated.

Squamous Cell Carcinoma (SCC) – is a common type of skin cancer, and is considered the most severe complication of HS.  Extensive scarring from HS is the biggest risk factor, but it is important to bear in mind that less than 3% of HS patients have gone on to develop SCC.  SCC lesions vary widely in appearance and any concerning lesions must be biopsied for diagnosis.  Regular skin checks, especially in areas with a lot of scarring, are the best way to prevent SCC.


Several diseases have been observed to accompany a diagnosis of Hidradenitis Suppurativa.  This is known as a comorbidity.  Although someone diagnosed with HS is more likely to have or develop one of the below listed conditions, it is important to note that no causal relationship has been established.  That means that it is not known if one condition causes the other, or if they have a common cause.  More research is needed.

Acne – One of the most obvious associations, but a distinct diagnosis.  HS shares similarities in appearance, and even some overlap in daily over the counter management, but not everyone with HS has had acne and HS is not merely a form of severe acne.

Pilonidal Cyst – A pilonidal cyst is an pocket in the skin, almost always located near the tailbone at the top of the cleft of the buttocks, that usually contains hair and skin debris.

Dissecting Cellulitis – Dissecting cellulitis is a chronic inflammatory disorder of the scalp with painful, fluid-filled nodules similar to Hidradenitis Suppurativa.  Blockage of the hair follicle may be a common cause between both Dissecting Cellulitis and HS, and Dissecting Cellulitis is also associated with severe acne, pilonidal cysts, and Crohn’s disease – all comorbidities of HS.

Irritable Bowel Syndrome & Inflammatory Bowel Diseases – Irritable bowel syndrome (IBS) is a common disorder that affects the large intestine. Symptoms include cramping, abdominal pain, bloating, gas, and diarrhea or constipation, or both.

Many diseases are included in this Inflammatory Bowel Disease (IBD) umbrella term. The two most common diseases are ulcerative colitis and Crohn’s disease.  Crohn’s disease can cause inflammation in any part of the digestive tract, most commonly the end of the small intestine while  ulcerative colitis involves inflammation of the large intestine.

Inflammatory Arthritis & Joint Disorders – Patients with HS are more likely to be diagnosed with inflammatory arthritis, including ankylosing spondylitis, rheumatoid arthritis, psoriatic arthritis, and other painful joint diseases.

Inflammatory arthritis is characterized by pain, swelling, stiffness and tenderness in the joints, especially large joints.  Because most inflammatory forms of arthritis are systemic (meaning they affect the entire body), the inflammation of the skin that defines HS may be connected to inflammation of the joints that some patients experience.

Polycystic Ovary Syndrome (PCOS) – Polycystic Ovary Syndrome is a common health problem caused by an imbalance of reproductive hormones that appears more frequently in women diagnosed with HS than in the general population. This hormonal imbalance creates problems in the ovaries, resulting in missed or irregular menstrual periods.  Other symptoms of PCOS include acne, thinning hair on a woman’s head and hair appearing on the face, chin, or other parts of the body where they usually do not appear on women.

Metabolic Syndrome and Cardiovascular Disease – Metabolic syndrome is the term for a group of risk factors – large waist size, high cholesterol, high blood pressure, and high blood sugars – that are risk factors for Type 2 Diabetes and Cardiovascular Disease.  Cardiovascular disease is a class of diseases that involve the heart or blood vessel, including heart attack, stroke, and heart failure.  Cardiovascular disease is the leading cause of death globally.

Individuals diagnosed with Hidradenitis Suppurativa are found to also be diagnosed with metabolic syndrome and cardiovascular diseases at a higher rate than the general population.  Because both metabolic syndrome and cardiovascular disease are generally regarded as preventable illness, dermatologists may routinely screen for blood pressure or fasting blood sugars as part of your management plan for HS.