Condition

Hidradenitis Suppurativa

Hidradenitis suppurativa (HS) is a long-term inflammatory skin condition that causes painful, deep lumps in the armpits, groin, under the breasts and around the buttocks. It is not an infection, and it is not caused by poor hygiene.
At a Glance

Hidradenitis suppurativa is an inflammatory condition that starts in the hair follicle. Follicles become blocked and burst under the skin, causing deep, painful lumps that keep coming back in the same skin folds, and that can join up over time into tunnels and thick scars.

It is not an infection, it is not contagious, and it has nothing to do with how clean you are. That matters, because most people with HS are told the opposite for years and handed antibiotic after antibiotic that never holds.

Nothing cures it. Good treatment reduces how often you flare and prevents new scarring, which is a real goal worth chasing. But tunnels and scars that already exist will not close on their own — those need surgery.

Key Facts

How CommonAbout 1 in 100 people. Badly under-diagnosed — most people wait years for the right name.
Who Gets ItUsually starts between the teens and the thirties. More common in women, and more common in Black patients.
Chronic or CurableChronic. It is controlled, not cured. Surgery can clear one area for good, but not the condition.
Rx RequiredYes, for anything past the mildest disease. Two biologics are FDA-approved for HS.
ContagiousNo. You cannot catch it or pass it on.
CostWide range. Antibiotics and washes are cheap. Biologics cost thousands per year at list price, but are usually covered once HS is documented in your notes.

Symptoms

HS almost always starts as a single painful lump that gets called a boil. What sets it apart is not the lump itself — it is that it comes back, and it comes back in the same few places.

What it looks and feels like

Deep, painful lumps — they sit under the skin rather than on it, and they hurt before anything is visible. Many people describe a burning or throbbing that starts a day or two early.
Lumps that open and drain — thick fluid or pus, often with a strong smell. The pain usually eases the moment one drains.
Blackheads in pairs — two or three dark dots close together in an area that has flared. These are a strong clue that it is HS and not a one-off boil.
Tunnels under the skin — narrow channels joining one spot to another, called sinus tracts. They leak on and off for months or years and they do not heal shut by themselves.
Rope-like scarring — thick, ridged scars in areas that have flared repeatedly. Skin can tighten enough to limit how far you lift your arm.
Recurrence in the same spots — this is the single most useful feature. A boil happens once. HS keeps returning to the same fold.

Where it shows up

  • Armpits — the most common site, and often the first.
  • Groin, inner thighs and genital skin.
  • Under the breasts and between them.
  • Buttocks and around the anus.
  • The waistband line, the back of the neck, and behind the ears — less common, but they happen.
  • Skin folds, in short. Places where skin rubs skin.

How it looks on different skin tones

On brown and Black skin the early inflamed lumps may look purple, dark brown or almost the same colour as surrounding skin rather than red, so early HS is easy to miss and easy to dismiss. Healed areas often leave dark patches, and the raised scarring can build into thick keloid-like ridges that are more prominent on darker skin. HS is both more common and often more severe in Black patients, and it is diagnosed later — worth knowing if you are trying to be taken seriously.

Light
Medium
Brown
Deep

HS is mistaken for several other things, and one of them is treated completely differently. See Lookalikes near the bottom of this page.

Causes & Risk Factors

HS is a disease of the hair follicle, not of the sweat glands, and not of dirt. The follicle becomes blocked, swells, and ruptures under the skin. The contents spill into the surrounding tissue, and the immune system reacts hard to something that should never have been there. That reaction is the pain, the swelling and the drainage. Bacteria can move into the damaged tissue afterwards, which is why antibiotics sometimes help for a while, but the bacteria are a passenger rather than the driver. This is why an antibiotic clears things for a few weeks and then it all comes back.

Genetics matter a great deal. About one in three people with HS has a close relative with it, and having a family history often means it starts earlier. On top of that, the immune system in HS is set to overreact, which is why the drugs that work best are the ones that dial down specific parts of it. Hormones play a part too — flares around periods are common, and it usually starts after puberty. Smoking and carrying extra weight are both genuinely linked to more severe HS, and changing either can make a measurable difference. Neither one caused this. Plenty of people with HS have never smoked and are not overweight, and no one develops HS because of something they did wrong.

What Hurts and What Helps

What Makes It Worse

  • Friction. Skin rubbing on skin, or tight clothing rubbing on skin. Waistbands, bra bands, tight jeans and seams that sit in a fold are common culprits.
  • Heat and sweat. Most people flare in summer and after exercise, especially when sweat is left to dry in a fold.
  • Smoking. This is the strongest modifiable factor in HS. Smokers have more flares and more severe disease, and quitting improves things for many people over months. This is not a moral point and it is not the reason you have HS.
  • Extra weight, for some people. More skin folds means more friction, and fat tissue itself is inflammatory. Weight loss reduces severity for a lot of people, though not for everyone, and some people with HS are thin.
  • Shaving and waxing the affected areas. Both irritate the follicle, which is where the whole problem starts.
  • Hormonal shifts. Many women flare in the week before a period.
  • Squeezing or lancing a lump at home. It empties for a day and comes back angrier, and it adds scarring.
  • Stress and poor sleep, which lower the threshold for a flare in most inflammatory skin conditions.

Daily Habits That Help

  • Loose, breathable clothing, especially in the areas that flare. Cotton next to the skin, and nothing with a seam sitting in a fold.
  • Washing with a gentle, fragrance-free cleanser. Scrubbing does not help and makes the skin sorer. HS is not a hygiene problem, so there is no amount of washing that fixes it.
  • A warm compress on a painful lump. It takes the edge off and sometimes helps one drain on its own, which is far better than opening it yourself.
  • Absorbent dressings over draining spots. They protect clothes, cut down friction and make the day easier. Plain gauze or a period pad works.
  • Stopping smoking. It is the single change with the biggest effect on the course of the disease.
  • Losing weight where that is realistic and wanted. It reduces flares for many people. It is one lever among several, not a condition of being treated.
  • Getting on treatment early. The scarring and the tunnels are the part that cannot be undone, so the value of treatment is largely in what it prevents. Waiting costs you skin.
  • Tracking your flares. Knowing your pattern makes it much easier to argue for stepping treatment up.

Try at Home

None of this treats the underlying inflammation, but it makes daily life with HS considerably easier and can reduce how often mild disease flares. Nothing here is a substitute for getting on prescription treatment.

Always
HS is not a hygiene problem, so washing is not treatment — but a mild, fragrance-free cleanser keeps sore folds comfortable without adding irritation. Skip scrubs, antibacterial bars and anything perfumed.
Loose clothing and less friction
Always
Friction sets off flares. Cotton next to the skin, nothing tight over the armpits, groin or under the breasts, and no seams or waistbands sitting in a fold. It costs nothing and most people notice the difference.
Stopping smoking
Always
Smoking does not cause HS, and it is not why you have it. But it is the strongest thing you can change: smokers flare more often and end up with more severe disease, and quitting improves things for many people over months rather than weeks.
Weight and metabolic health
Always
Carrying extra weight is linked to more severe HS, partly through friction in folds and partly because fat tissue is itself inflammatory. Losing some weight reduces flares for many people. Plenty of people with HS are thin, this is not the cause, and it is never a condition of being treated.
Limited evidence
An antibacterial wash used a few times a week on the affected folds. It may cut down on surface bacteria and reduce smell. The evidence in HS is thin, and it will not stop lumps forming — treat it as a cheap add-on, not a plan. It bleaches towels and dark clothing.
Limited evidence
An antiseptic wash used as an alternative to benzoyl peroxide, and it does not bleach fabric. Same honest limits: it reduces bacteria on the skin surface and does nothing about the inflammation driving the disease. Keep it away from the eyes and ears.
A warm compress
A clean flannel wrung out in warm water, held on a painful lump for ten minutes a few times a day. It eases the throbbing and sometimes helps a lump drain on its own, which is far better than opening it yourself. It will not shorten the flare.

When to See a Dermatologist

If you have had more than one painful lump in the same fold, book an appointment. Do not wait for it to get worse, and do not accept "a boil" as an answer for the third time.

  • Two or more painful lumps in the same area, ever.
  • Lumps in the armpit, groin, under the breasts or on the buttocks that keep coming back.
  • Anything that drains, or any spot that has stayed open.
  • Repeated courses of antibiotics that work for a few weeks and then stop.
  • Pain that limits how you move, sit, work or sleep.

What the visit gets you: a name, which is the part most people have been waiting years for. Then a stage, which decides what is worth trying. Then an actual plan — a wash and a topical for mild disease, a longer antibiotic course or a hormonal option for moderate disease, and a biologic for anything more than that. A dermatologist can also drain a lump properly under local anaesthetic, inject a steroid into a painful one for fast relief, and refer for surgery on tunnels that will never settle.

Go the same day, or to urgent care, if an area is spreading fast, hot and hard with a fever. That suggests infection spreading in the skin, which is different from an HS flare and needs treating quickly.

What Happens at the Dermatologist?+

HS is diagnosed by looking and by history. There is no blood test or scan for it, and no test is needed to make the diagnosis.

Swabs are the test you will most likely be offered, and they are usually not helpful. A swab of draining fluid often grows normal skin bacteria, or grows nothing at all. Neither result changes the diagnosis. HS is not an infection, so a swab that comes back clear does not mean nothing is wrong with you, and a swab that grows something does not mean you simply have a skin infection. A swab is genuinely useful in one situation: when an area looks infected on top of the HS and your doctor needs to know which antibiotic will work.

A few other tests come up:

  • Blood tests are used to check for the conditions that travel with HS rather than to diagnose it — blood sugar and cholesterol, and sometimes thyroid or hormone levels if there are other signs. They are also required before starting some medications.
  • Imaging (ultrasound or MRI) is used before surgery, to map how far the tunnels run under the skin. What you can see on the surface is usually less than what is underneath.
  • A biopsy is uncommon. It is done when the diagnosis genuinely does not fit, not to confirm typical HS.

If you are asked to keep coming back for repeat swabs and repeat antibiotics with no plan beyond that, it is fair to ask what the result would change.

Prescription Treatments

What you are offered depends on your stage. Mild disease starts with a topical and a wash, moderate disease usually means a longer antibiotic course or a hormonal option, and anything beyond that is where the biologics come in. Two are FDA-approved specifically for HS.

Topical prescriptions
Moderate evidence
The standard first prescription for mild HS. Applied twice a day to the affected folds, it reduces the number of inflamed spots. It works on the surface only, so it does nothing for deep lumps or tunnels, and it is usually paired with a benzoyl peroxide wash to slow resistance.
Topical prescriptions
Limited evidence
A peeling cream applied to a lump at the first sign of a flare. Many people find it shortens how long a painful lump lasts. It is a compounded product, so not every pharmacy makes it, and it commonly causes peeling and a brownish discolouration of the treated skin.
Pills and injections
Moderate evidence
Usually the first tablet tried, taken for about three months. In HS it is used for its anti-inflammatory effect rather than to kill an infection. It helps a lot of people with mild to moderate disease, and it commonly stops holding — that is expected, and it means moving up rather than repeating the course forever.
Pills and injections
Moderate evidence
Two antibiotics taken together for about ten weeks, the standard next step when doxycycline is not enough. It works for many people with moderate HS. Rifampin turns urine, tears and sweat orange, can stain contact lenses, and makes hormonal birth control less reliable — use a backup method.
Pills and injections
Limited evidence
A hormone-blocking tablet, useful for women whose flares track with their periods. It takes about three months to judge. Evidence in HS is mostly from case series rather than trials, and it is not used in men because of breast tenderness and enlargement.
Pills and injections
Limited evidence
A diabetes tablet sometimes added in HS, particularly alongside polycystic ovary syndrome or insulin resistance. Small studies suggest fewer flares. The evidence is weak, it is a slow one to judge, and stomach upset in the first few weeks is common.
Pills and injections
Strong evidence
The first biologic FDA-approved for HS, and the usual choice for moderate to severe disease. It is an injection you give yourself, and it blocks a specific inflammatory signal rather than killing bacteria. Expect to judge it at 12 weeks. Roughly half of people get a clear benefit, and it does not close tunnels that already exist.
Pills and injections
Strong evidence
The second biologic approved for HS, and a genuine option if adalimumab did not work or stopped working. Also a self-given injection, blocking a different inflammatory signal. Same honest framing: it reduces new flares, it takes about three months to judge, and it will not clear existing tunnels.

In-Office Treatments

Procedures do the job medication cannot: emptying a painful lump now, and removing tunnels and scarring that will never close on their own. Surgery is a normal part of HS care, not a last resort or a failure.

Moderate evidence
A tiny amount of steroid injected straight into an inflamed lump. It is the fastest relief available for a single bad spot, often settling it within a day or two. It treats that one lump and nothing else, and repeated injections in the same place can thin the skin.
Limited evidence
Opening a swollen lump under local anaesthetic to let it empty. The relief is immediate and real. The honest catch is that in HS it almost always refills, because the lining stays behind — it is pain relief, not treatment, and repeated draining adds scarring. Deroofing is the version that lasts.
Moderate evidence
The roof of a tunnel is removed under local anaesthetic and the base is left open to heal from the bottom up. It is the treatment for a tunnel that keeps leaking, and the treated spot usually stays clear for good. Healing is slow and needs dressing for a few weeks, and new spots can still appear elsewhere.
Moderate evidence
Removing a whole affected area, used for advanced disease where a fold is full of tunnels and scarring. It is the closest thing to a permanent fix for that area. It is real surgery with a long recovery, sometimes needing a skin graft, and HS can still start in a different fold afterwards.
Moderate evidence
Because HS starts in the hair follicle, destroying follicles in an affected fold can reduce flares. The Nd:YAG laser is the one studied in HS and is safe on darker skin. It suits mild to moderate disease, needs several sessions, and is often not covered by insurance.

What to Expect

Step 1
Understanding the stages
  • Doctors sort HS into three stages, and the stage decides what is worth trying.
  • Stage 1: one or a few lumps, no tunnels, no scarring. Most people are here for years.
  • Stage 2: repeated lumps in more than one area, with some tunnels and scarring, but separated by normal skin.
  • Stage 3: whole areas involved, with tunnels joining up across a fold. This is the stage biologics and surgery are aimed at.
Step 2
The first few months of treatment

Pain and new lumps usually settle before anything looks better. Judge a treatment by how often you are flaring, not by whether the old scarring has changed.

Step 3
On a biologic

Most people who respond notice fewer new lumps within 12 weeks. If nothing has moved by then, it is reasonable to switch rather than wait it out. Around half of people get a meaningful response, which means this is worth trying and also worth having a second option ready.

Step 4
After surgery

Deroofing and excision heal slowly and are often left open to heal from the base up, which can take weeks. The area that was operated on usually stays clear. New spots can still appear elsewhere, because the surgery treated the damage, not the disease.

Step 5
The honest long view

HS is a lifelong condition that runs in flares. Nothing available now cures it. Treatment aims at fewer and shorter flares, less pain, and no new tunnels. Existing tunnels and scars will not close on their own no matter how good the medication is — that is a separate job. Many people find it quietens down over the years, and some women find it settles after menopause.

Complications

HS is not dangerous in the short term, but it is a condition where waiting costs something real, because the damage is what does not reverse.

Scarring and tunnels
Repeated flares in one spot leave thick, ridged scars and sinus tracts. These are permanent without surgery. This is the main reason to treat early rather than ride it out.
Restricted movement
Heavy scarring in the armpit or groin can tighten enough to limit how far you lift your arm or how comfortably you walk.
Infections on top
Damaged skin can get genuinely infected. Spreading redness, heat, hardness and fever are the signs, and that needs same-day care.
Lymphoedema
Long-standing inflammation in the groin can block lymph drainage and cause persistent swelling of the genital skin or leg.
Anaemia and low mood from chronic pain
Long-term inflammation and ongoing drainage take a physical toll, and constant pain and unpredictable flares take a mental one. Depression and anxiety are more common in HS than in most skin conditions, and that is a reasonable thing to raise at an appointment.
Other conditions that travel with it
HS is linked to higher rates of diabetes, high cholesterol, polycystic ovary syndrome and inflammatory bowel disease. This is why blood tests get checked, and it is worth knowing rather than worrying about.
Skin cancer, rarely
Squamous cell carcinoma can develop in areas that have been inflamed and scarred for decades, most often on the buttocks in men. It is uncommon, but it is the reason a long-standing area that changes, hardens or will not heal should be looked at.

Lookalikes

HS is misdiagnosed constantly, usually as one of these. The detail that separates them is almost always whether it comes back in the same place.

  • A boil (furuncle) — a single painful lump from an infected follicle. It comes to a head, drains, heals, and that is the end of it. HS is the one that returns to the same fold again and again. If you have been told "boils" more than twice, that word is probably wrong. See boil vs abscess.
  • An abscess — a walled-off pocket of pus, usually a one-off, and it settles for good once drained. HS lumps refill. See abscess vs cyst.
  • Epidermoid cysts — smooth, firm, often painless lumps with a single central dot, and they do not come in clusters in a fold. They only hurt if they rupture.
  • Folliculitis — small, shallow, whitehead-like spots at hair follicles. It sits on the surface, HS sits deep.
  • Ingrown hairs and razor bumps — appear after shaving or waxing, in the shaved area, and settle when you stop. Confusingly, shaving also triggers HS, so the two can overlap.
  • Acne — HS is sometimes called acne inversa, and both start in the follicle. But acne is on the face, chest and back, not in the folds, and it does not tunnel.
  • Crohn's disease of the skin — can cause tunnels and open sores around the anus and groin that look very like HS, and the two occur together. Bowel symptoms are the clue, and worth mentioning if you have them.
  • Pilonidal disease — a tunnel and opening at the top of the buttock crease only. If that is the sole site, it is more likely pilonidal than HS.
FAQ+
Is hidradenitis suppurativa caused by poor hygiene?No. This is the most damaging myth about HS and it is simply wrong. HS is an inflammatory condition of the hair follicle. No amount of washing prevents it, and scrubbing makes sore skin sorer. People with HS often wash more than average, not less.
Is it contagious?No. You cannot catch it or give it to anyone, including through sex or shared towels.
Is HS an infection?No. Bacteria can settle into skin that is already damaged, which is why antibiotics sometimes help for a while, but they are not the cause. This is why antibiotic after antibiotic stops working.
Why did it take so long to get diagnosed?Most people wait years and see several doctors first. The early lumps look like boils, they are in places people are reluctant to show, and HS is not well taught. The delay is common and it is not your fault. Saying "these keep coming back in the same place" is the phrase most likely to get you taken seriously.
Can hidradenitis suppurativa be cured?No. Treatment reduces flares and prevents new damage. Surgery can clear one area permanently, but the condition can still appear elsewhere.
Will the tunnels close if I take the medication?No. Tunnels and scars are structural damage. Medication stops new ones forming and calms the inflammation, but existing tunnels need deroofing or surgery to go.
Should I pop or lance a lump at home?No. It gives a day of relief, comes back worse, and adds scarring. A dermatologist can drain one properly, or inject a steroid into it, which usually settles a painful lump in a day or two.
Does losing weight cure it?No, but it helps many people flare less. Weight is one factor among several, and plenty of people with HS are not overweight. It is worth doing if you can, and it is not a condition of getting treatment.
Does quitting smoking really make a difference?Yes. It is the change with the strongest effect on how severe HS becomes. Improvement takes months rather than weeks.
Does diet cause HS?No diet causes it. Some people report fewer flares cutting back on dairy or on brewer's yeast, and the evidence for that is weak. It is reasonable to try if you want to, and not something to feel guilty about skipping.
Is HS linked to other conditions?Yes. Diabetes, high cholesterol, polycystic ovary syndrome and inflammatory bowel disease are all more common in people with HS, which is why blood tests get checked.
What is the best treatment for severe HS?A biologic — adalimumab (Humira) or secukinumab (Cosentyx) are both FDA-approved — usually combined with surgery for tunnels that will not settle. Around half of people respond well to a given biologic, so a second option often gets tried.