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Is HS an infection? How it differs from boils, staph, and cellulitis
Hidradenitis suppurativa (HS) isn't an infection. Learn how HS differs from staph, MRSA, boils, and cellulitis, and when recurring lumps need a dermatologist.
Key takeaways
Hidradenitis suppurativa (HS) is a chronic inflammatory skin condition, not a contagious infection. HS lumps can sometimes develop a separate bacterial infection.
Painful lumps that repeatedly appear in areas such as the armpits, groin, or under the breasts may be HS rather than isolated boils.
Antibiotics can reduce HS inflammation or treat a secondary infection, but recurring HS often requires ongoing treatment tailored by a dermatologist.
Drainage, odor, and scarring can occur with HS. A dermatologist can evaluate recurring lumps even if you are unsure what is causing them.
Seek prompt medical care for rapidly spreading redness, fever, or chills, which may indicate a serious infection.
Hidradenitis suppurativa (HS) is a chronic inflammatory skin condition, not a bacterial infection. Unlike common skin infections, HS is not contagious and is not caused by poor hygiene. However, HS lumps can resemble boils and may sometimes develop a secondary infection, making the two easy to confuse.
As our hidradenitis suppurativa condition guide explains, HS is caused by too much inflammation in the skin. The clearest clue is the pattern: painful lumps that keep returning in the same skin folds.
Because HS can resemble ordinary boils, diagnosis is sometimes delayed. Understanding the differences can help you recognize when recurring lumps warrant evaluation by a dermatologist.
What makes HS different from a skin infection
A skin infection starts when bacteria get into the skin and multiply. HS starts differently, with inflammation inside the hair follicle (the tiny pocket each hair grows from).
Bacteria still play a part. Bacteria on the skin or inside HS lumps can add to the inflammation. An HS lump can also develop a secondary infection, which means a new infection on top of the existing lump.
Pus can make this confusing. Mayo Clinic's HS overview notes that secondary infection is possible, but pus is common in HS and doesn't necessarily mean infection.
That's why a clinician, rather than the look of a lump, sorts out what's happening. HS also can't be spread to other people, including family members and partners.
HS, boils, MRSA, and cellulitis side by side
In the moment, these four conditions can look alike. The differences usually show up over time, in where lumps appear and how they behave.
HS | Boil | Staph or MRSA abscess | Cellulitis | |
|---|---|---|---|---|
What causes it | Long-term inflammation in hair follicles | Infection of a hair follicle, most often by Staphylococcus aureus bacteria | Bacterial infection; MRSA is staph that can resist several antibiotics | Bacterial infection of the deeper layers of the skin |
What it looks like | Deep, painful lumps in skin folds such as the armpits, groin, buttocks, inner thighs, and under the breasts | A red, painful lump that fills with pus | A red, swollen, painful, warm bump with pus, sometimes with fever | Red, swollen, warm, painful skin, sometimes with fever or chills; most common on the feet and legs |
How it behaves over time | Returns in the same areas and can leave scars and tunnels under the skin | Usually needs to open and drain to heal, most often within 2 weeks | Looking at it can't tell you whether it's MRSA | The red area can spread, sometimes quickly |
Can it spread to others? | No, HS is not contagious | Squeezing can spread the infection, so don't squeeze it or share towels | Yes, through contact with infected skin, wounds, or shared items | In general, people can't catch it from others |
How it's confirmed and treated | Diagnosed by a clinician from the pattern; managed with a long-term treatment plan | Warm compresses; sometimes drainage or antibiotics from a clinician | A lab test of a sample confirms MRSA; treated by a clinician | Treated with antibiotics; get care right away if redness spreads quickly |
Use this table as a guide to the differences, not as a way to diagnose yourself. A clinician can examine the lump and, when needed, test a sample.
Staph and MRSA infections
Staph (Staphylococcus aureus) is a common type of bacteria. MRSA (methicillin-resistant Staphylococcus aureus) is a type of staph that can be resistant to several antibiotics.
A MRSA skin infection often looks like a red, swollen, painful bump that feels warm and may drain pus. That can look a lot like an HS lump.
The CDC guidance on MRSA states that you cannot tell by looking at the skin whether it's a MRSA infection. To find out, a clinician may send a sample from the lump to a lab.
Contact a clinician if a lump comes with a fever or doesn't improve within 48 hours. In the meantime, don't pick at or pop it.
Cellulitis
Cellulitis is a bacterial infection of the deeper layers of the skin. It usually shows up as a warm, red, swollen, painful area rather than a single lump.
Cellulitis is most common on the feet and legs, while HS tends to appear in skin folds. In general, people can't catch cellulitis from others.
Cellulitis can become serious if it isn't treated. The CDC cellulitis warning signs call for medical attention right away if the red area spreads quickly or you develop a fever or chills.
What's the difference between a boil and an HS abscess?
A boil is a bacterial infection of a hair follicle that usually drains and heals. An HS abscess (a painful, pus-filled lump) sits deeper and tends to come back.
MedlinePlus, which explains how boils form and heal, says boils usually need to open and drain to heal, most often within 2 weeks. They are most often caused by Staphylococcus aureus bacteria.
HS lumps follow a different course. They tend to return in the same place or nearby, and they often appear in more than one skin fold. Over time, HS can leave scars and tunnels under the skin.
A single boil is common and usually heals once it drains. Boils that keep returning in the same folds are worth showing to a dermatologist. Our article on boils that keep coming back explains what repeat boils can mean and who to see.
Whatever the cause, don't squeeze or cut lumps at home. Squeezing a boil can spread the infection.
Why antibiotics can help for a while without stopping HS
A course of antibiotics that calms a flare, followed by lumps that come back, is a common pattern with HS. It makes sense once you know what antibiotics can do in HS.
Antibiotics are a real part of HS treatment. Some antibiotics help calm inflammation and reduce the skin bacteria that add to it. They can also treat a secondary infection when one is present.
The American Academy of Dermatology and the HS Foundation released new HS treatment guidelines in October 2026. The guidelines conditionally recommend systemic antibiotics, which work throughout the body to decrease symptoms and improve quality of life. Options named include doxycycline, tetracycline, clindamycin combined with rifampin, and ertapenem.
HS, though, is a long-term inflammatory condition. A short course of antibiotics for a presumed infection may quiet one flare. Meanwhile, the underlying inflammation can keep producing new lumps.
That's why HS care is usually a longer-term plan that a dermatologist builds and adjusts with you. It may include medicines applied to the skin, pills, and procedures. It may also include biologic medicines, which are injections or infusions that target specific sources of inflammation.
Feeling better on antibiotics doesn't by itself show whether a lump was an infection or HS. Your dermatologist looks at the whole pattern to decide.
Why does my skin keep breaking open in the same spot?
In HS, inflammation weakens the hair follicle until it breaks open under the skin. The body responds with more inflammation, a painful lump forms, and it may drain pus or fluid.
As the lump heals, it can leave a scar, and new lumps tend to form in the same area. The AAD's guide to HS notes that you may develop more abscesses in the same area. If abscesses and scars keep appearing, pus-filled tunnels can form under the skin.
Mayo Clinic notes that these tunnels can connect lumps under the skin. That is one reason drainage may keep returning to the same area.
Drainage and odor are common with HS, and they aren't a sign of poor hygiene. It's understandable if they feel embarrassing.
Patterns that suggest HS include:
Lumps in the same skin folds, such as the armpits, groin, buttocks, or under the breasts
Lumps that heal, scar, and come back
Our article on lumps under the breasts that scar explains why HS inflammation can sit deeper than drainage reaches.
How a dermatologist diagnoses HS
There's no single blood test or skin test for HS. A dermatologist makes the diagnosis by looking at the type of lumps, where they appear, and how they've come and gone over months.
Your history matters as much as the exam. Specialized training gives dermatologists deep expertise in diagnosing skin conditions, including ones that closely resemble each other.
Your dermatologist may take a swab to check for infection. A biopsy (a small skin sample) is occasionally used when the picture is unclear or to rule out other conditions.
Early HS can look like boils or acne, so getting the right name for it can take time. A StatPearls clinical review of HS, hosted by the National Library of Medicine, notes that diagnosis is often delayed by an average of 7 years. It links that delay to how closely HS resembles other conditions.
A few things can make your visit more useful:
Photos of flares, since a lump may look different by the day of your visit
A simple log of where and when lumps appear
A list of past treatments and how each one worked
You don't need medical terms to explain what's going on. You might say, "I keep getting painful lumps in my armpits and groin. Antibiotics help for a few weeks, then they come back in the same places."
When to see an HS specialist, and when to get care right away
You don't need to be sure it's HS to book a visit. Describing what you've noticed is enough for a dermatologist to start sorting it out.
Consider seeing a dermatologist experienced in HS if you notice:
Lumps that keep returning in the same folds
Lumps in more than one area of the body
Lumps that come back within weeks of treatment
Scars or tunnels under the skin
Pain that limits movement or daily life
Seeing a dermatologist earlier may reduce flare-ups and help keep HS from worsening.
Get care right away at an urgent care clinic or emergency department if redness spreads quickly or you develop a fever or chills. These signs need prompt attention whether or not you have HS.
At Tono, our dedicated HS specialty program covers diagnosis, biologic management, and stepping up treatment when needed. It also includes long-term follow-up and coordination of procedural care.
Every visit is led by a specialist. Visits can take place by video or in person, and procedural care, such as drainage or surgery, is coordinated in person when needed.
Tono's co-founder and Chief Medical Officer is Dr. Mondana Ghias, a board-certified dermatologist and recognized authority in HS who has authored more than two dozen peer-reviewed publications, including award-recognized research advancing the treatment of the disease. Tono has cared for more than 20,000 patients across a 33-state clinical footprint.
Frequently asked questions
Is HS a sexually transmitted infection?
No. HS can appear in the groin and genital area, but it isn't sexually transmitted and can't be passed to a partner.
Can a boil turn into HS?
A boil and HS are different conditions, but boil-like lumps that keep coming back may be HS from the start. The American Academy of Dermatology notes that lumps like these, when they return often and repeatedly, could be HS. A dermatologist can help you check.
Is HS the same as acne?
No. According to the American Academy of Dermatology, HS can look like pimples and acne cysts, but it is not acne. HS is sometimes called acne inversa, and it forms deeper, in skin folds.
Is there a cure for HS?
There's no cure for HS yet, but treatment can help. The American Academy of Dermatology notes that treatment can help prevent new lumps, treat existing ones, and ease pain.
Can I see an HS specialist by video?
Yes, for many visits. By video, a dermatologist can review your history and photos, explain what may be happening, and manage your treatment over time.
Getting answers about recurring lumps
Lumps that keep coming back in the same places form a pattern worth naming. Once HS has a name, you and your dermatologist can focus on treatment designed for HS rather than one flare at a time.
If this sounds familiar, you can schedule an in-person or virtual appointment with a Tono Health specialist. Appointments are often available within days, most insurance is accepted, and no referral is needed.
You can review our insurance and access details before you book. When you're ready, find an HS specialist and choose the visit type that works for you.
