Hidradenitis Suppurativa: What It Is and Why It Is Often Diagnosed Late
Medically reviewed by Dr. Abdul Hadi Jafri — Consultant
Hidradenitis suppurativa (HS, also called acne inversa) is a chronic inflammatory skin disease that begins with blockage of the hair follicles. It causes painful lumps, abscesses, and tunnels under the skin in fold areas such as the armpits, groin, and under the breasts. It is often mistaken for recurrent boils, which can delay diagnosis.
What is hidradenitis suppurativa?
Although the name points to the sweat glands, the process starts with blockage and inflammation of a hair follicle. When inflammation recurs in skin folds, it can produce:
- Painful nodules: firm bumps under the skin.
- Abscesses: inflamed collections that may drain fluid or pus.
- Tunnels (sinus tracts): channels that form with repeated inflammation and can leave scarring.
It is a chronic disease that tends to flare and settle over time, and its severity varies from person to person.
Where does it usually appear and what does it look like?
The condition tends to appear where skin rubs against skin and hair follicles are plentiful:
- Under the armpits.
- The groin (upper inner thighs) and around the genital area.
- Under the breasts and within skin folds.
- Sometimes the buttock area.
It may start as a single painful lump that resembles a boil, then keep returning in the same spot. This recurrence in the same areas is what distinguishes it from a passing boil.
Why is it diagnosed late, and how common is it?
The condition is frequently misdiagnosed as recurrent boils or a simple infection, which delays a correct diagnosis. A systematic review and meta-regression analysis published in JAMA Dermatology in 2021 estimated how common the disease is:
- A pooled global prevalence of about 0.40% of the population after combining studies.
- A higher prevalence in clinical samples (about 1.7%) than in general population-based studies (about 0.3%).
These results indicate that the disease may remain undiagnosed. The review also noted that most available data came from Western European and Scandinavian countries, the US, and Australia, and that more reliable detection requires standardised diagnostic tools.
How is it diagnosed?
Hidradenitis suppurativa is primarily a clinical diagnosis, meaning it relies on the doctor's examination and the history of symptoms more than on a single decisive test. A doctor usually recognises it from:
- The type of lesions: painful nodules, abscesses, and tunnels.
- Their location: the fold areas described above.
- Their recurrence: returning in the same sites over a period of time.
A doctor may use additional tools when needed, but diagnosis is primarily clinical. Tell the doctor when symptoms began, where they occur, how often they return, and whether they have left scars.
Is it contagious or caused by poor hygiene?
No. Hidradenitis suppurativa is not an infection passed from person to person, and it is not caused by a lack of hygiene. It is a chronic inflammatory disease linked to the process of blockage and inflammation in hair follicles. This clarification matters, because the mistaken belief that it is "a matter of cleanliness" can add embarrassment and delay seeking medical help.
When should you see a doctor?
Consult a dermatologist when:
- Painful lumps keep returning in the same areas (such as the armpit or groin), for example two or more times within six months.
- Abscesses recur, drain fluid, or leave scars.
- Pain or discomfort affects movement, sleep, or quality of life.
- You are repeatedly told you have "boils" without steady improvement.
Early assessment can confirm the diagnosis and organise follow-up.
Source: Study published in JAMA Dermatology, 2021 — DOI: 10.1001/jamadermatol.2021.1677
Frequently asked questions
Is hidradenitis suppurativa just recurrent boils?
No. Although it can start as a boil-like lump, it is a chronic inflammatory skin disease that begins with blocked hair follicles and tends to recur in the same areas. Confusing it with boils is one reason it is diagnosed late.
Is it common?
According to a systematic review published in 2021, pooled global prevalence was about 0.40% and about 1.7% in clinical samples. The review noted that the condition often remains undiagnosed.
Where does it usually appear?
Most often in fold areas where skin rubs against skin: the armpits, groin, under the breasts, and sometimes the buttocks.
Is it contagious or due to poor hygiene?
No, it is neither contagious nor caused by poor hygiene. It is a chronic inflammatory disease linked to blockage and inflammation of hair follicles.
When should I see a doctor?
When painful lumps recur in the same areas (for example two or more times in six months), abscesses keep returning, pain affects your daily life, or you are repeatedly told you have "boils" without steady improvement.