Facts & Figures - Hidradenitis Suppurativa Explained

Who can have HS?

  • The global prevalence rate of hidradenitis suppurativa (HS) is estimated to be about 1%.1
  • However, because the condition is often misdiagnosed and many people living with HS don’t always feel comfortable talking about their symptoms or seeking out their dermatologist for help, the number of people who are actually diagnosed with HS is far less than this estimate.2-4
  • HS can occur at any age, but the condition most commonly develops in young adults in their early 20s; prevalence usually reduces after the age of 50 to 55.5
  • Women are more likely to develop HS than men.2,5


  • HS is a chronic skin condition characterised by inflamed areas typically located around the armpits and groin. These inflamed areas often include painful lesions, nodules and boils, and usually occur where certain sweat glands (known as apocrine glands) are located, as well as under the breasts, on the buttocks and in the inner thighs, where skin rubs together.1-4,6

Where can HS develop?

  • With apocrine glands (sweat glands in areas with abundant hair follicles) such as the armpits and groin.2,3,5,6
  • Where skin rubs together, such as under the breasts, the buttocks, the inner thighs.2,3,6


  • Though the exact causes of HS are unclear, research suggests that the root of HS lies in specific defects within hair follicles.2,7
  • Other recent research has hypothesised that inflamed lesions associated with HS tend to develop when there is a blockage of hair follicles and inflammation of sweat glands in the apocrine family, which are found in areas such as the armpits and groin.1,2,6
  • It is thought that this blockage can occur when sweat becomes trapped inside sweat gland tubes, which eventually swell up and either burst or become severely inflamed.8

When is it time to talk to a dermatologist?

  • If you or someone you know is experiencing recurring, painful nodules or boils in the armpits or groin area, it is important to see a dermatologist to ensure proper diagnosis and care. You will need to first see your GP for a referral to a dermatologist.


  1. Collier F, Smith R, Morton C. Diagnosis and management of hidradenitis suppurativa. BMJ 2013;346:f2121.
  2. Zouboulis CC, Tsatsou F. Disorders of the apocrine sweat glands. In: Goldsmith LA, Katz SI, Gilchrest BA, Paller AS, Leffell DJ, Wolff K. Fitzpatrick’s Dermatology in General Medicine. 8th ed. New York, Chicago: McGraw Hill; 2012. p947–959.
  3. Kurzen H, Kurokawa I, Jemec GB, et al. What causes hidradenitis suppurativa? Exp Dermatol 2008;17:455–456; discussion 457–472.
  4. Fimmel S, Zouboulis CC. Comorbidities of hidradenitis suppurativa (acne inversa). Dermatoendocrinol 2010;2:9–16.
  5. Jemec GB. Clinical practice. Hidradenitis suppurativa. N Engl J Med 2012;366:158–164.
  6. Mayo Clinic. Hidradenitis Suppurativa. Available at: http://www.mayoclinic.org/diseases-conditions/hidradenitis-suppurativa/home/ovc-20200012. Accessed April 2021.
  7. Danby FW, Jemec GB, Marsch WCh, von Laffert M. Preliminary findings suggest hidradenitis suppurativa may be due to defective follicular support. Br J Dermatol 2013;168:1034–1039.
  8. The British Association of Dermatologists. Hidradenitis Suppurativa. Available at: http://www.bad.org.uk/for-the-public/patient-information-leaflets/hidradenitis-suppurativa. Accessed April 2021.


AU-HUM-210053 August 2022.