There is a good chance that you know about acne, commonly known as pimples. But you may not be familiar with hidradenitis suppurativa (HS)! HS is a skin condition that can resemble acne in its early stages, but it has unique features that evolve over time, leading to chronic inflammation deep in the skin. HS causes painful bumps called boils in areas with many sweat glands and hair follicles, such as the armpits. Some patients may experience uncontrollable body odor because of their inflammation. The cause of HS is unknown, but there are many educated guesses as to what contributes to HS. The physical, mental, and emotional pain caused by HS makes its treatment complex. The goals of this article are to increase awareness and understanding of HS, and to empower people living with HS and those who care about them.
Overview of The Skin
The skin is the largest organ in the body, and it is made up of three layers (Figure 1). The skin also contains hairs, sweat glands, and oil glands (also called sebaceous glands). The major functions of the skin include protection from outside elements such as the sun or infections; production of sweat and oil; temperature maintenance; fat storage; synthesis of vitamin D3; and sensory functions, like feeling touch, heat, and texture .
What is Hidradenitis Suppurativa?
While you have probably heard of acne, you may not have heard of hidradenitis suppurativa (HS). HS is an inflammatory condition that affects the sebaceous glands and sweat glands in the skin, as well as the hair root, called the hair follicle. These structures are deep in the second layer of the skin, the dermis (Figure 1). The glands and/or hair follicles can get infected and form bumps under the skin. Sometimes they get clogged by proteins and fats that are normally made by the glands and hair follicles. The clogged follicles and glands cause boils (big bumps) to form. The body tries to fight this infection by activating its army—the immune system. Some of the “soldiers” overreact and cause damage to the skin. As the inflammation spreads, the bumps connect with each other and form a ropy network of debris within the skin . When the body tries to heal, scarring occurs. Figure 2 shows the progression of HS inside the skin.
In its early stages, HS can look like acne, forming small red bumps on the skin. As it progresses, it can cause pus (dead white blood cells), abscesses (swollen areas within body tissue, containing pus), odor, inflammation, tunnels under the skin, scars, and impaired movement . HS can be mistaken for other conditions, including ingrown hairs, herpes (a viral infection), or classic boils. The difference is that HS is a chronic condition that often does not respond to the treatments used for these other conditions.
HS affects 4 in 100,000 people , and it can affect kids, teens, and adults. The average age of onset is 12.5 years, coinciding with the onset of puberty . HS affects more females than males and tends to “flare” or get worse before menstrual periods, suggesting that hormones may play a role in HS. For unknown reasons, rates of HS are higher in African Americans compared to other races . People with a family member who has HS have an increased risk of developing the condition, indicating a possible genetic cause. HS is not contagious, meaning that you cannot catch it from being in contact with someone who has it, and it cannot be passed on to others. HS is not due to poor hygiene and doctors have not found any specific products (soaps, deodorants, lotions) that can trigger HS. Like other inflammatory diseases, it is likely that HS can be triggered by different things in different people.
How is HS Diagnosed?
Presently, there are no laboratory tests that can diagnose HS. Instead, diagnosis is based on a physical examination. Doctors identify HS by how the boils look, their locations, how frequently the boils come and go, and whether they leave scars . There are three stages of HS, from mild to severe, known as Hurley Stages 1, 2, and 3 (Figure 2).
Potential Causes of HS
The exact cause of HS is unknown, but there are several hypotheses. One possibility is that genetic mutations (changes in the DNA blueprints in our cells) increase the risk of HS . Another idea is that the immune system overreacts to bacteria normally present on the skin . Researchers have found differences in the types of bacteria present on the skin of people with HS compared to people without HS . Byrd et al. discovered that higher numbers of immune cells called neutrophils and B cells, and higher amounts of the substances these cells make, result in more severe HS . Smoking is one of the biggest environmental risk factors in HS [6, 8, 9]. If HS patients can quit smoking, they can improve the course of their HS. Smoking increases inflammation, which is why doctors think it contributes to HS. These are only a few of the proposed causes of HS. Many researchers are dedicating their time and resources to identifying the main factors involved in HS and how they interact to cause the condition.
How is HS Treated?
Treatment of HS depends on the stage. The goal is to treat the current episode and stop new boils (Figure 3) from forming. Pain management is one of the biggest challenges for individuals with HS [8, 9]. Over-the-counter pain medication, like aspirin, Advil® or Tylenol® can help. Doctors can drain the boils to help relieve pain and reduce the risk of infection . Doctors can treat infected HS boils with topical (on the skin) and oral antibiotics. Sometimes bleach baths with diluted bleach are also recommended. This kills bacteria and can reduce the number of HS boils. For severe HS in people over 12 years old, strong anti-inflammatory medications can be prescribed. The next level is laser treatment and surgery. With lasers, doctors can destroy the hair follicles and decrease the development of protein plugs. Laser treatment also helps prevent the growth of the ropy network. In severe cases, surgery to drain the pus from the boils might be the best approach.
How Does HS Impact Those Affected?
HS can affect mental wellness, so it is important to make sure people living with HS have the social support they need. Many people have not heard about HS. Individuals with HS often do not discuss the condition because they are worried about being accepted, or whether others will even know what HS is. Presently, there is no cure for HS and treatment options are limited. The cycle of boils, abscesses, and ropy networks causes scars. The smell can cause feelings of shame. Making and keeping friends might be difficult, which affects self-esteem . Boils in the groin affect participation in sports or other activities because friction on the inner legs from walking or running can cause pain and discomfort .
Living with HS may impact academic performance, due to school absences during flares or because of doctor’s appointments. The impact of all these difficulties can cause increased anxiety, depression, and suicide risk in individuals with HS .
To create a supportive environment for your peers who are living with HS, it might be helpful to talk to your school health provider and your teacher about what HS is. Efforts to increase awareness of HS have led to creation of support groups that can make life easier for people living with the condition.1 Now that you are knowledgeable about HS, its causes, treatments, and mental and social impacts, you can be more compassionate to your peers who might be suffering from HS. Even better, you can spread the word about this condition, to empower others to support people with HS, too!
We thank HS patients for their perseverance through this difficult disease.
Sebaceous Glands: ↑ Oil producing gland and sebum.
Hidradenitis Suppurativa: ↑ A condition characterized by inflammation of sweat glands and formation of pus.
Hair Follicle: ↑ The root or deepest part of the hair.
Boils: ↑ A swollen area within body tissue and containing pus in the upper layer of the skin.
Inflammation: ↑ Redness, swelling, and pain.
Abscess: ↑ A swollen area within body tissue and containing pus in the deeper layer of the skin.
Chronic: ↑ A condition that lasts a long time.
Conflict of Interest
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
 ↑ Marieb, E., and Hoehn, K. 2010. Human Anatomy and Physiology, 8th Edn. San Francisco, CA: Pearson Education..
 ↑ Saunte, D. M. L., and Jemec, G. B. E. 2017. Hidradenitis suppurativa: advances in diagnosis and treatment. JAMA. 318:2019–32. doi: 10.1001/jama.2017.16691
 ↑ Garg, A., Lavian, J., Lin, G., Strunk, A., and Alloo, A. 2017. Incidence of hidradenitis suppurativa in the United States: a sex- and age-adjusted population analysis. J. Am. Acad. Dermatol. 77:118–22. doi: 10.1016/j.jaad.2017.02.005
 ↑ Garg, A., Kirby, J. S., Lavian, J., Lin, G., and Strunk, A. 2017. Sex- and age-adjusted population analysis of prevalence estimates for hidradenitis suppurativa in the United States. JAMA Dermatol. 153:760–4. doi: 10.1001/jamadermatol.2017.0201
 ↑ Seyed Jafari, S. M., Hunger, R. E., and Schlapbach, C. 2020. Hidradenitis suppurativa: current understanding of pathogenic mechanisms and suggestion for treatment algorithm. Front. Med. 7:68. doi: 10.3389/fmed.2020.00068
 ↑ Byrd, A. S., Carmona-Rivera, C., O’Neil, L. J., Carlucci, P. M., Cisar, C., Rosenberg, A. Z., et al. 2019. Neutrophil extracellular traps, B cells, and type I interferons contribute to immune dysregulation in hidradenitis suppurativa. Sci. Transl. Med. 11:eaav5908. doi: 10.1126/scitranslmed.aav5908
 ↑ Thorlacius, L., Cohen, A. D., Gislason, G. H., Jemec, G. B. E., and Egeberg, A. 2018. Increased suicide risk in patients with hidradenitis suppurativa. J. Invest. Dermatol. 138:52–7. doi: 10.1016/j.jid.2017.09.008
 ↑ Choi, E., Ting, O. X., and Chandran, N. S. 2020. Hidradenitis suppurativa in pediatric patients. J. Am. Acad. Dermatol. 86:140–7. doi: 10.1016/j.jaad.2020.08.045