Hidradenitis Suppurativa (Acne Inversa) vs. Folliculitis: What's the Difference?

Why both terms come up

Folliculitis means that hair folliclesHair Follicle: The tube-shaped pocket in the skin from which a hair grows. In Acne Inversa, the follicle becomes plugged and eventually ruptures, spilling its contents into surrounding tissue and triggering the inflammatory cascade that defines the disease.Hair FollicleThe tube-shaped pocket in the skin from which a hair grows. In Acne Inversa, the follicle becomes plugged and eventually ruptures, spilling its contents into surrounding tissue and triggering the inflammatory cascade that defines the disease.Read more in the glossary are inflamed. It can look like small pimples or pustules on hair-bearing skin. Early hidradenitis suppurativa can also start with inflamed nodulesNodule: A firm, palpable lump deep in tissue. Nodules can be painful and may progress to abscesses. They are among the typical early signs of Acne Inversa.NoduleA firm, palpable lump deep in tissue. Nodules can be painful and may progress to abscesses. They are among the typical early signs of Acne Inversa.Read more in the glossary. As a result, both conditions are often lumped together in everyday thinking.

Medically, what matters more precisely is how the lesions look and how they behave over time.

What tends to point to folliculitis

Folliculitis often presents with smaller papules or pustules centred around hair follicles. It can itchPruritus (Itch): Itch. Often overlooked in Acne Inversa because pain dominates, but a significant minority of patients rate itch as the most distressing symptom, particularly during the healing phase of lesions.Pruritus (Itch)Itch. Often overlooked in Acne Inversa because pain dominates, but a significant minority of patients rate itch as the most distressing symptom, particularly during the healing phase of lesions.Read more in the glossary, burn, or feel tender to the touch. Depending on the cause, it can occur on various hair-bearing areas of the body.

This doesn’t mean folliculitis is always harmless. It just means its typical appearance doesn’t automatically indicate an HS diagnosis.

What looks different in HS

Hidradenitis suppurativa becomes more likely when symptoms:

• sit deeper and are clearly painful,
• recur as nodules or abscessesAbscess: An inflamed cavity or swelling containing pus or fluid. In hidradenitis suppurativa, abscesses can form as part of the inflammatory disease process and do not automatically mean that a bacterial infection is present. Secondary bacterial infection can occur and may require separate medical assessment. In Acne Inversa, abscesses occur mainly in the armpits, groin, and other skin folds.AbscessAn inflamed cavity or swelling containing pus or fluid. In hidradenitis suppurativa, abscesses can form as part of the inflammatory disease process and do not automatically mean that a bacterial infection is present. Secondary bacterial infection can occur and may require separate medical assessment. In Acne Inversa, abscesses occur mainly in the armpits, groin, and other skin folds.Read more in the glossary,
• concentrate in typical skin fold regions,
• open up, weep, or leave scars,
• develop hardened areas, recurring openings, or tunnelsSinus Tract: A tunnel-like channel under the skin that forms between abscesses or nodules. Sinus tracts indicate more advanced disease and can chronically drain fluid. They are associated with Hurley Stages II and III.Sinus TractA tunnel-like channel under the skin that forms between abscesses or nodules. Sinus tracts indicate more advanced disease and can chronically drain fluid. They are associated with Hurley Stages II and III.Read more in the glossary (sinus tracts).

A few superficial pustules and a recurring deep nodule are different observations. This distinction is exactly what helps during a medical appointment.

The course over time also matters

Folliculitis and HS can look similar at individual sites. Even involvement of the groin or armpit isn’t automatic proof of HS. What matters is whether medical professionals recognise a recurring HS pattern: typical lesions, typical locations, and a chronic or relapsing course.

If your skin happens to be calmer at the time of the appointment, notes or photos of active episodes can help describe the course more clearly.

When you should get it checked out

Recurring painful nodules in typical HS regions should be assessed by a dermatologist, even if earlier episodes were labelled as folliculitis. If there is rapid worsening, fever, or sharply increasing pain, prompt medical attention is needed.