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Why do HS boils smell and keep draining?
Why do HS boils smell and keep draining? Learn what causes the odor, why tunnels under the skin keep leaking, and when to see an HS dermatologist for care.
Key takeaways
The smell from hidradenitis suppurativa (HS) lumps comes from the condition, not from being unclean. Odor is common, and there's no reason to feel embarrassed about seeking care.
A spot in your armpit or groin can look healed on top but still leak from a tunnel under the skin. That can explain why the same place keeps draining and smelling.
Gentle washing, soft dressings and loose clothing can help you stay comfortable day to day. Scrubbing harder or squeezing lumps can make things worse.
Lumps that keep coming back in the same places should be seen by a dermatologist experienced in HS. You can ask about medicine and simple procedures that calm the inflammation and treat tunnels that keep draining.
Get care right away if you have a fever, red streaks from the sore, or a lump filling with a lot of fluid. These can be signs of an infection that needs prompt treatment.
Boils from hidradenitis suppurativa (HS) can smell because pus and bacteria collect inside lumps and tunnels. They can keep draining because HS may form tunnels under the skin that stay inflamed even when the surface looks calm.
Living with HS smell and drainage can leave you worried that other people will notice. That worry is common and understandable. Odor is a symptom of a medical condition, and many people with HS experience it.
You can read more about what hidradenitis suppurativa is on our condition page. This guide explains why HS drainage and smell happen and how to manage them day to day. It also covers which treatments reduce drainage and when to see an HS specialist.
Why HS lumps and boils smell
When an HS lump opens, it releases pus and dead tissue. Bacteria in the lump or tunnel are linked to the smell.
Tunnels can trap debris, such as keratin (a protein in skin and hair) and hair fragments. A 2025 review of HS tunnels in JID Innovations says this debris may help bacteria attach and form biofilm, a sticky layer of germs. The same review notes that tunnels are often linked with pus-like, bad-smelling discharge.
It also notes that Gram-negative anaerobes, a group of bacteria that grow without oxygen, dominate in long-lasting HS lumps and tunnels. These bacteria may add to the smell and the inflammation. HS itself is an inflammatory condition, not an infection.
The smell comes from the disease, not from how often or how well you wash.
Why HS can keep draining after it looks healed
Tunnels, also called sinus tracts, are channels under the skin that can connect lumps and keep leaking fluid. A tunnel sits deep in the skin, so the surface can look calm while the tunnel underneath stays inflamed.
Tunnels tend to form as HS persists or worsens. The NIH overview of HS describes HS as a chronic, noncontagious, inflammatory condition with painful bumps or boils and tunnels in and under the skin. Over time, these bumps can become inflamed areas with chronic drainage.
Draining treats the lump on the surface, but it may not reach a deeper tunnel. Your dermatologist may look for signs like these:
The same spot leaks again and again.
Fluid comes out when your dermatologist presses on nearby skin during an exam. Please don't try this at home.
An opening reappears where a lump had closed.
Rope-like scars form in the area.
Not every lump becomes a tunnel. The NIH describes connected tunnels mainly in more severe cases, and tunnels can drain for a long time once they form.
Gentle washing and dressings can help with drainage and bacteria on the skin, but they aren't designed to treat a tunnel. The American Academy of Dermatology (AAD) advises telling your dermatologist if any wound fails to heal or opens up after healing. Procedures such as deroofing, covered below, are used for tunnels.
Is it a regular boil or HS?
An ordinary boil is an infected hair follicle that usually drains and heals. HS follows a pattern over time.
Feature | Ordinary boil | A pattern that suggests HS |
|---|---|---|
Where it appears | Most common on the face, neck, armpits, buttocks and thighs | Armpits, groin, buttocks, inner thighs or under the breasts |
How often it returns | May happen once, though some people get boils again | Returns in the same areas over months or years |
Whether it refills after draining | Usually heals once it opens and drains, often within about 2 weeks | Often refills or flares again in the same spot |
Tunnels | Not a typical feature | Tunnels can form under the skin |
Scarring | Can occur, but usually less extensive | Can leave significant scarring |
One side vs both sides | Can appear on one or both sides | Often affects both sides of the body |
Response to antibiotics | Often helped by drainage and, when needed, antibiotics | Antibiotics may calm a flare, but lumps can return once the course ends |
If you have had boils that keep coming back, that pattern is worth a closer look. There is no blood or lab test for HS. A dermatologist diagnoses it from your history and a skin exam, so what you describe matters.
On darker skin, inflammation may look purple, gray or brown rather than red. Our guide to how HS looks on darker skin explains what to watch for.
HS also affects the groin, buttocks and the skin under the breasts. If your lumps appear lower on the body, you can learn more about recurring groin and buttock lumps.
Managing odor and drainage day to day
Home care can help keep your skin comfortable between visits. It works best alongside a treatment plan from a dermatologist.
Wash gently, not harder
Wash affected areas gently and pat dry with a soft towel. An antimicrobial wash can reduce bacteria on the skin.
The AAD shares dermatologists' HS self-care tips that name two options. One is an acne wash with benzoyl peroxide, and the other is a soap or shampoo with zinc pyrithione. Your dermatologist may suggest a different antiseptic wash.
Scrubbing can seem like the answer to odor, but it causes inflammation that can make HS worse. The AAD puts it plainly: "You don't have dirty skin. You have a skin condition."
Choose dressings that absorb and protect
Cover draining spots with the dressings your dermatologist recommends and follow your wound-care plan. The AAD says some people need to change dressings several times a day at first.
You can ask your dermatologist which dressings suit your skin and how best to hold them in place. Your dermatologist will consider where your wounds are and how much they leak.
Make clothing and deodorant work for you
These habits can help limit flares and irritation:
Choose looser clothing if tight or form-fitting clothes make HS flare.
Try to avoid sweating and overheating, which can trigger flares.
Choose gentle, hypoallergenic skin products.
For the armpits, choose a mild deodorant or antiperspirant. The AAD says certain ingredients, such as fragrance and alcohol, can irritate skin and lead to a flare-up.
What to skip
Squeezing or popping lumps
Draining lumps at home
Waxing (if you shave, take care to avoid nicks)
Scrubbing
Deodorants or antiperspirants with fragrance, alcohol or other irritating ingredients
Medical treatments that reduce drainage
Treatment aims to reduce lumps, drainage and flare-ups, the things the odor comes from. A dermatologist experienced in HS builds a plan in steps, based on how active and widespread your HS is. You can ask your dermatologist how to track odor and drainage together.
HS can't be cured, but the AAD says a treatment plan can reduce flare-ups and keep the condition from worsening.
Medicines that calm inflammation
Your dermatologist may combine more than one of these, depending on your HS:
Topical treatments, such as antibiotic lotions, for mild HS
Antibiotic pills to calm inflammation and reduce bacteria
Steroid injections for painful lumps that are not infected
Spironolactone, a hormone-related medicine that may help some women
Biologics, injected medicines that target the immune signals behind HS
HS is not an infection, but antibiotics are often prescribed to reduce inflammation and bacteria, as the AAD guide to treatment options dermatologists use explains. As of October 2026, the FDA has approved three biologics for moderate-to-severe HS. Adalimumab and secukinumab are approved for ages 12 and older, and bimekizumab is approved for adults.
In studies, biologics reduced lumps and abscesses and slowed the formation of new draining tunnels in many patients. Results vary, and tunnels that have already formed may still need a procedure.
Procedures for tunnels that keep draining
The new joint HS guidelines from the AAD and the HS Foundation, released in October 2026, list several in-office procedures:
Deroofing, a minor treatment that opens and flattens a tunnel so it can heal from the base
Incision and drainage to treat a painful abscess
Surgical removal for abscesses or tunnels that persist or keep coming back
Laser hair removal can also reduce the number of lumps and pus-filled bumps in some people.
Draining a painful abscess can bring real relief. The tunnel or inflamed follicle underneath may remain, so the lump can return.
The AAD lists a returning lesion as a possible outcome, even after in-office surgery. Draining should be done by a clinician, not at home.
Procedures happen in person. Planning and follow-up can often happen by video.
When to see an HS specialist
Lumps that smell, drain or return to the same places should be seen by a dermatologist, ideally one experienced in HS.
You don't need to know whether it's HS before booking. Simply describe what you're experiencing.
Get care right away for these signs
Get care right away if you notice:
A fever
Feeling generally unwell
Red streaks coming out from the sore
A large build-up of fluid in the area
MedlinePlus lists fever, red streaks and fluid build-up among the signs a boil needs care, and it lists general ill-feeling as a boil symptom. It also advises contacting a medical professional when boils come back after treatment.
Only a clinician can tell whether a sore is infected. Your dermatologist may swab a bit of the fluid so it can be tested.
Bring the odor and drainage into the visit
Odor is worth mentioning, even if it feels hard to say out loud. One study on odor and quality of life of 51 patients with HS described odor as a common symptom. In that study, worse odor was linked to lower quality of life on one questionnaire, the Skindex-29, even after accounting for disease severity.
It helps to bring:
Dated photos taken during flares
A timeline of when lumps started and how often they return
A list of every affected area, including spots that seem healed
What you have tried, such as washes, dressings, drainage or antibiotics
You can describe it in your own words. For example: "One spot under my arm closed weeks ago, but it still leaks and smells."
How Tono's HS specialists can help
Tono's HS specialty program brings together board-certified dermatologists who treat every stage of HS. They handle diagnosis, biologic management, treatment changes over time and coordination of procedures.
HS appointments are available in 2 days or less. No referral is needed, most insurance is accepted, and every visit is led by a specialist. Tono has cared for more than 20,000 patients across a 33-state clinical footprint.
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.
Video visits are one way to reach the right specialist. Diagnosis, medicine and biologic management, and follow-up can often happen virtually. Cultures, biopsies, injections and procedures happen in person, coordinated by your care team.
Dr. Ghias explains more about why virtual-first HS care works.
The smell is a signal, not a verdict
Odor and drainage that persist are information. They can point to tunnels and inflammation, which a dermatologist can assess and treat. Sharing that information at your visit helps your dermatologist build the right plan.
Frequently asked questions
Does HS cause body odor beyond the lumps?
The odor of HS comes from draining lumps and tunnels. If you're worried about body odor beyond these areas, mention it to your dermatologist.
Does a strong smell mean my HS is infected?
Not necessarily. Bad-smelling drainage is a common part of HS, and only a clinician can tell whether a sore is infected. Watch for the warning signs listed earlier and get care if they appear.
Can I still use deodorant if I have HS in my armpits?
Yes. The AAD recommends a mild antiperspirant or deodorant without alcohol, baking soda, parabens, dyes or fragrance. Ask your dermatologist about using it near open skin.
Will the smell go away once I start treatment?
Treatment aims to reduce the draining lumps and tunnels the odor comes from, and timing varies from person to person. Tunnels that keep draining may need a procedure, since the tunnel review notes they can respond less well to medicine, even biologics.
Is HS contagious?
No. HS cannot spread to other people through touch, shared towels or intimacy.
Schedule an in-person or virtual appointment with a Tono Health specialist.
