Hidradenitis suppurativa (HS) is a chronic skin condition that causes painful lumps, abscesses, and tunnels beneath the skin, typically in areas where skin rubs together like the armpits, groin, buttocks, and under the breasts. It affects roughly 1% of the global population and is notoriously under-recognized, with an average delay of 10 years between first symptoms and a correct diagnosis.
What Happens Under the Skin
HS starts in hair follicles, not sweat glands, despite older theories. The process begins when the lining of a hair follicle thickens and plugs the opening. That blockage causes the follicle to swell until it eventually ruptures, spilling its contents (dead skin cells, bacteria, and debris) into the surrounding tissue. Your immune system treats this like an invasion, sending waves of inflammatory cells to the site and forming a painful abscess.
When this cycle repeats in the same area over months and years, the damage becomes structural. The body attempts to heal with scar tissue, but the ongoing inflammation undermines that repair. Tunnels form between abscesses beneath the skin surface, creating interconnected channels that can drain fluid and pus. These tunnels rarely resolve on their own and are one of the hallmarks that distinguishes HS from ordinary boils or ingrown hairs.
Who Gets It and Why
HS typically appears after puberty, most commonly between the late teens and early 30s. Women make up about 56% of cases. The condition has a strong genetic component: roughly 35% of people with HS have a family history of it. Researchers have identified mutations in a group of genes involved in a cellular signaling pathway, with 57 specific mutations documented across three genes so far. These mutations appear to disrupt how skin cells develop and shed, setting the stage for follicular plugging.
Genetics alone don’t tell the whole story. Smoking is one of the strongest modifiable risk factors, with smokers about three times more likely to develop HS than nonsmokers. Obesity roughly doubles the risk, likely because excess weight increases friction and moisture in skin folds while also promoting systemic inflammation. Neither smoking nor weight causes HS on its own, but both can trigger flares and worsen severity in people who are already predisposed.
What Flares Feel and Look Like
The earliest sign is usually a deep, tender lump under the skin that resembles a boil. It may be the size of a pea or grow to the size of a golf ball. These nodules are often hot, red, and painful well before they’re visible on the surface. Some resolve partially on their own, only to recur in the same spot weeks or months later. Others progress to full abscesses that eventually rupture and drain thick, foul-smelling fluid.
Pain is the symptom that dominates daily life for most people with HS. It ranges from a dull throb during quieter periods to sharp, debilitating pain during active flares. Sitting, walking, raising your arms, or wearing fitted clothing can become excruciating depending on where lesions are located. Over time, scarring can limit the range of motion in affected areas, and chronically draining tunnels can stain clothing and carry a persistent odor that many patients describe as one of the most socially isolating aspects of the disease.
How Severity Is Classified
Doctors use the Hurley staging system to describe how far the disease has progressed:
- Stage I: One or more abscesses without tunnels or scarring. Flares come and go with relatively healthy skin in between.
- Stage II: Recurrent abscesses with some tunnel formation and scarring, but the affected areas are still separated by normal skin.
- Stage III: Widespread involvement across an entire region, with multiple interconnected tunnels and abscesses. Large areas of scarring make it difficult to distinguish individual lesions.
Most people are diagnosed at Stage I or II. Progression isn’t inevitable, but without treatment and risk factor management, the disease tends to worsen over time.
Why Diagnosis Takes So Long
The average person with HS waits a full decade from their first symptoms to getting a correct diagnosis. Part of the delay is that early HS looks like common skin problems: boils, ingrown hairs, or infected cysts. Many people treat flares at home for years without seeking medical care, or they see doctors who misdiagnose the condition. There’s no blood test or biopsy that confirms HS. Diagnosis is clinical, based on three criteria: typical appearance (nodules, abscesses, or tunnels), typical location (skin folds), and a pattern of recurrence over at least six months.
If you’ve had recurring painful lumps in your armpits, groin, or under the breasts, and they keep coming back in the same areas, that pattern is worth bringing to a dermatologist’s attention specifically.
Managing Pain During Flares
Pain management in HS depends on the severity of the flare. For mild episodes, over-the-counter anti-inflammatory medications like ibuprofen or naproxen can take the edge off. Topical pain relievers also help: lidocaine cream applied directly to the skin numbs the surface, and topical anti-inflammatory gels can reduce swelling at the site.
For more intense flares, a dermatologist can inject a small dose of a steroid directly into an inflamed nodule or abscess, which often shrinks it and relieves pressure within a day or two. Incision and drainage of an acute abscess provides immediate relief but is considered a short-term measure since the underlying problem remains. Menthol-based creams can provide a cooling sensation that some patients find helpful between medical visits.
Long-Term Treatment Options
Treating HS is about reducing flare frequency, preventing new tunnels from forming, and managing inflammation over the long haul. For mild disease, topical antibiotics applied directly to affected skin can help control bacterial overgrowth that fuels inflammation. Oral antibiotics taken for longer courses (weeks to months) are commonly used for moderate disease, though they work more as anti-inflammatory agents than infection fighters in this context.
For moderate to severe HS, biologic therapy is the most significant treatment advance in recent years. A biologic that blocks a key inflammatory protein called TNF-alpha is the only FDA-approved medication specifically for HS, available for adults and adolescents 12 and older. In clinical trials, 42% to 59% of patients on this treatment achieved a meaningful reduction in abscesses and inflammatory nodules within 12 weeks, compared to 26% to 28% on placebo. That means it doesn’t work for everyone, but for those who respond, it can substantially reduce flare frequency and pain.
When Surgery Is Needed
Surgery enters the picture when tunnels and scarring don’t respond to medications. Two main approaches exist, each suited to different situations.
Deroofing is a less invasive procedure where the roof of a tunnel is removed, leaving the base to heal from the bottom up. It works well for individual tunnels and has a recurrence rate of about 27%. Recovery is relatively straightforward, and the procedure can often be done under local anesthesia.
Wide local excision is reserved for advanced disease, particularly Hurley Stage III, where large areas of skin are riddled with interconnected tunnels. The surgeon removes all affected tissue down to the deep layer beneath the fat, with margins extending beyond the visible disease. This is a more involved surgery with a longer recovery, but recurrence rates are lower at around 13%. How the wound is closed matters: skin grafts and flaps have the lowest recurrence rates (6% to 8%), while direct closure carries a slightly higher chance of the disease returning.
Related Health Conditions
HS doesn’t exist in isolation. The chronic inflammation driving the skin disease appears to raise the risk of several other conditions. Crohn’s disease is one of the most well-documented associations. In one large study, 38% of HS patients also had a Crohn’s disease diagnosis, a striking overlap that suggests shared inflammatory pathways between the gut and skin.
Diabetes, metabolic syndrome, and cardiovascular disease also occur at higher rates in people with HS. Some of this connection is mediated through shared risk factors like obesity, but the systemic inflammation of HS itself likely contributes independently. Other associated conditions include certain types of inflammatory arthritis and a rare syndrome involving joint inflammation, bone lesions, and severe acne.
One common assumption is that HS is linked to polycystic ovary syndrome (PCOS), but research has not supported this. Studies have found that acne, excess hair growth, and irregular periods are no more common in people with HS than in the general population.
Lifestyle Changes That Help
Because smoking and obesity are the two strongest modifiable risk factors, addressing them can meaningfully change the course of the disease. Quitting smoking won’t cure HS, but many patients report fewer and less severe flares after stopping. Weight loss reduces friction in skin folds and lowers the systemic inflammatory load that drives the disease.
Practical daily measures include wearing loose, breathable clothing to minimize friction, using gentle cleansers rather than harsh scrubs on affected areas, and avoiding shaving in regions prone to flares. Warm compresses can help bring a developing nodule to a head or ease discomfort. Some people find that certain foods trigger flares, though this varies widely and no single diet has been proven effective for HS as a whole.