Hidradenitis Suppurativa vs. Boil: How to Tell When a Recurring “Boil” Needs a Closer Look

A single painful lump can be difficult to distinguish from a boilBoil (Furuncle): Patient-community term for an inflammatory nodule or abscess. Important caveat: an ordinary single boil (furuncle) is a one-off bacterial hair-follicle infection. The recurring, multifocal 'boils' of Acne Inversa are not the same thing — this misdiagnosis is a main reason HS goes unrecognised for years.Boil (Furuncle)Patient-community term for an inflammatory nodule or abscess. Important caveat: an ordinary single boil (furuncle) is a one-off bacterial hair-follicle infection. The recurring, multifocal 'boils' of Acne Inversa are not the same thing — this misdiagnosis is a main reason HS goes unrecognised for years.Read more in the glossary by appearance alone. The pattern becomes more informative when you look at three things together: what the lesion is like, where it occurs, and whether similar lesions keep returning. This guide shows what makes HS worth raising with a clinician, without trying to diagnose a lump from a photograph or checklist.

HS or a boil? The short answer

One lump is often not enough to tell.

A boil is usually an infection involving a hair follicleHair 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. Hidradenitis suppurativa (HS, also called Acne Inversa) is a chronic inflammatory skin disease that can also produce painful lumps and abscessAbscess: 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-like lesions.

HS becomes more important to consider when painful or draining lumps repeatedly occur in characteristic areas such as the armpits, groin, genital or perineal region, buttocks or under the breasts, especially if they return in the same regions or leave scars 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.

European and German S2k guidance uses a history of recurrent painful or suppurating lesions (at least twice within six months), together with characteristic locations and clinical findings, as part of the diagnostic assessment.

That pattern is a reason for medical assessment, not a diagnosis you should make from this page.

What is the difference between HS and a boil?

HS and a boil compared, feature by feature

Feature	A boil can look like	HS becomes more suspicious when
Pattern over time	A single episode can occur.	Similar painful or draining lesions keep returning.
Location	Can occur on many hair-bearing areas.	Repeated lesions affect characteristic areas such as armpits, groin, genital or perineal area, buttocks or under the breasts.
Number of areas	May remain an isolated lesion.	Similar lesions occur in more than one characteristic body region.
Healing	Often resolves as the acute infection settles.	Lesions recur, heal slowly or leave persistent changes.
Scarring	A severe boil can scar, so scarring alone does not prove HS.	Recurrent lesions leave repeated, characteristic scarring.
Tunnels under the skin	Not typical of an ordinary isolated boil.	Draining or non-draining tunnels strongly increase suspicion of established HS.
Drainage / pus	Common.	Also possible in HS. Pus alone does not distinguish the two.
Fever / rapidly spreading redness	Can indicate a more significant infection.	Needs prompt medical assessment whether or not HS is also present.

No single row diagnoses HS. The combination and the history matter.

The useful question is not “What does it look like today?”

Early HS can resemble a boil, abscess, inflamed cystCyst: A fluid- or keratin-filled sac under the skin. In Acne Inversa some lesions resemble epidermoid cysts but differ histologically. The term is used loosely in clinical practice.CystA fluid- or keratin-filled sac under the skin. In Acne Inversa some lesions resemble epidermoid cysts but differ histologically. The term is used loosely in clinical practice.Read more in the glossary, folliculitis or an ingrown hair. That is one reason diagnosis can be delayed.

Instead of trying to identify one lump from its appearance, look at the pattern across time:

1. What happened? Was it a deep painful lump, abscess-like swelling, a draining area or a recurring opening? Did it leave a scar or a persistent tract-like area?
2. Where did it happen? HS commonly affects skin-fold and friction-prone areas including the armpits, groin, genital and perineal region, buttocks and the folds under the breasts.
3. Has it happened before? Recurrence is one of the most useful clues. The diagnostic history in current guidance includes recurrent painful or suppurating lesions, at least twice within six months.

A clinician combines that history with an examination of the skin and consideration of other possible causes.

”But mine contains pus. Doesn’t that mean it is an infection?”

Not necessarily.

Pus is common in boils because boils are usually bacterial infections of hair follicles. HS lesions can also contain or drain pus-like material, and an HS lesion can develop a secondary infectionSecondary Bacterial Infection: A bacterial infection that develops in skin already affected or damaged by another condition. Open or draining HS lesions can sometimes become secondarily infected. This is a possible complication of HS, not the underlying cause of the disease.Secondary Bacterial InfectionA bacterial infection that develops in skin already affected or damaged by another condition. Open or draining HS lesions can sometimes become secondarily infected. This is a possible complication of HS, not the underlying cause of the disease.Read more in the glossary.

That means pus alone cannot tell you whether a lesion is HS or a boil. It also does not mean every boil needs antibiotics; that is a clinical decision.

Fever, rapidly spreading redness, increasing warmth, marked swelling or feeling generally unwell can indicate infection or another problem needing prompt medical assessment. Do not use an HS diagnosis, or a suspicion of HS, to dismiss new signs of infection.

Does HS look different from a boil?

Sometimes, but not reliably enough to diagnose yourself from a picture.

More established HS may show multiple lesions, characteristic scars or tunnels that make the pattern easier to recognise. Early HS may be much less distinctive and can appear as a single deep painful lump.

To see how HS can appear across body areas and skin tones, use the visual guide. Treat images as pattern education, not as a diagnostic test.

See the HS Visual Guide →

If this keeps happening, prepare the pattern, not just today’s lesion

If you have had several episodes called “boils,” “abscesses,” “infected cysts” or “ingrown hairs,” the most useful thing to bring to an appointment is the pattern across those episodes.

Try to reconstruct:

• where each episode occurred;
• roughly when it happened;
• whether the same area was affected before;
• whether it drained;
• whether a scar or persistent opening remained;
• what clinicians previously called it;
• whether you received antibiotics, drainage or another treatment.

You do not need perfect records. An approximate history is still more informative than treating every episode as unrelated. If you are comfortable doing so, photos taken during an active episode can complement it.

Recurring “boils” and no HS diagnosis yet? The Could This Be HS? Appointment Pack helps you organise previous episodes, locations, labels and treatments into a one-page summary for a clinician. It does not calculate a diagnosis or tell you whether you have HS.

Prepare my appointment summary →

For how the diagnosis itself is made, see How HS is diagnosed. If your lump looks more like a small surface pimple, see HS vs. folliculitis.

When should recurring boils be assessed for HS?

Consider arranging a medical assessment if painful or draining “boils”:

• keep returning;
• recur in the same area;
• occur in characteristic HS locations such as the armpits, groin, genital or perineal region, buttocks or under the breasts;
• occur in several of these regions;
• leave repeated scars or persistent openings;
• develop tunnel-like areas beneath the skin; or
• continue despite previous treatment for presumed boils or abscesses.

A dermatologist can assess whether the pattern fits HS or whether another diagnosis explains it better.

Seek prompt medical assessment for a lesion that is rapidly worsening or comes with spreading redness, severe escalating pain, fever, chills or feeling significantly unwell. Those features can need assessment for infection or another acute problem whether or not HS is present. See when to get medical help with HS.

What this comparison cannot tell you

This page cannot determine whether a particular lump is HS.

A single boil does not mean you have HS. Recurrent boils do not automatically mean HS either. Conversely, a lesion that looks infected does not rule HS out.

The purpose of this comparison is narrower: to recognise when a repeated pattern deserves assessment as a pattern rather than as another isolated episode.