Skin & hair

Adalimumab, the First HS Biologic

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For years, hidradenitis suppurativa had no biologic medicine developed and tested specifically for it. That changed when two large placebo-controlled trials tested adalimumab in HS and it became the first FDA-approved biologic for the disease. Here is what the drug actually does, how the trial evidence reads, where it fits against topical antibiotics and surgery, and what happens when it stops being enough.

Last updated: July 2026History

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What Hidradenitis Suppurativa Is, and Why It Needed Its Own Biologic

Hidradenitis suppurativa is a chronic inflammatory skin disease that produces painful nodules, abscesses, and draining tunnels under the skin, most often in the armpits, groin, and other skin folds, driven by immune activity around hair follicles rather than by poor hygiene 1. For years, dermatologists managing severe HS reached for biologic drugs built and approved for other diseases; adalimumab became the first biologic to earn an approval specifically for hidradenitis suppurativa, on the strength of two large randomized trials designed around this disease 2. Severity is typically staged by how much skin is involved, whether tunnels have formed under the surface, and how the lesions are distributed and connected to one another — the framework that determines when a case has moved past topical and oral treatment and into biologic territory 3. That staging system groups disease into broad categories, from isolated abscesses without tunnels at the milder end to widespread, interconnected tunnels across an entire region at the more severe end, and it is the same framework clinicians use to decide whether medical treatment alone is still reasonable or whether a procedure needs to happen alongside it 3.

How Adalimumab Works

Adalimumab is a TNF-alpha inhibitor: it binds and neutralizes tumor necrosis factor-alpha, a signaling protein that drives much of the inflammation in HS lesions, rather than suppressing the immune system broadly 1. TNF-alpha (tumor necrosis factor-alpha) is an inflammatory signaling protein that adalimumab blocks. Blocking that signal does not reverse tunnels or scarring that have already formed; it mainly reduces how many new, actively inflamed nodules and abscesses appear going forward. The same drug class also includes tnf inhibitors for psoriasis, since TNF-alpha drives inflammation in several chronic skin diseases beyond HS — but each disease needed its own trial evidence, and a drug working well for psoriasis was not itself proof it would work as well for HS, which is exactly why dedicated hidradenitis trials were needed before adalimumab could be approved for it.

What the PIONEER Trials Actually Showed

Adalimumab's HS approval rests on two identically designed, placebo-controlled trials, called PIONEER I and PIONEER II, that enrolled adults with moderate-to-severe hidradenitis suppurativa and measured how many reached a meaningful drop in inflamed lesions by week twelve 2. Significantly more people on adalimumab reached that response than people on placebo — the finding regulators relied on to approve the drug. Running the same trial design twice, independently, and getting the same answer both times is part of why the result was convincing: a single positive trial can be a statistical fluke, but two separate trials pointing the same direction is much harder to explain away. As with any biologic, not everyone who starts adalimumab reaches that treatment response, which is why response is usually checked at a defined point rather than assumed.

Where Adalimumab Sits on the HS Treatment Ladder

Adalimumab is rarely a first treatment. The hs treatment ladder typically starts with antiseptic washes plus clindamycin for hs applied topically for limited, milder disease, moves through hs oral antibiotics such as combined regimens for more active disease, and considers hormonal treatment for hidradenitis in some patients before reaching for a biologic 3. Adalimumab generally enters the picture at more extensive disease — multiple interconnected lesions or early tunnels — or when those earlier steps haven't brought the disease under control. Staging isn't just paperwork: it's what tells a clinician and patient whether the next reasonable step is a stronger antibiotic course, a biologic, or hs surgery for tunnels that have already formed and won't respond to any drug alone.

What a Biologic Doesn't Treat

Hidradenitis suppurativa carries comorbidities that a biologic like adalimumab doesn't address by itself — smoking and obesity are both strongly associated with the disease and with how severe it runs, and metabolic conditions cluster with HS more than they do in the general population 1. None of that means a biologic is pointless if those factors are present; it means adalimumab is one part of managing a disease that usually has more than one lever working on it at once. Wound care, smoking and weight counseling, and treating any coexisting conditions tend to move alongside drug therapy rather than being replaced by it, and a dermatology team managing HS well is usually coordinating more than the injection alone.

What Happens When Adalimumab Isn't Enough

Not everyone who starts adalimumab reaches or keeps a meaningful response, and HS can break through a biologic that worked initially 2. When that happens, the newer biologics reaching for hs — drugs targeting a different inflammatory pathway, IL-17, rather than TNF-alpha — are an option clinicians now have that didn't exist when adalimumab was the only approved biologic for the disease. Switching drug classes rather than simply stopping treatment is often the more useful move, since a drug that fails on one inflammatory pathway doesn't predict failure on a different one. Tunnels that have already formed are a separate problem from active inflammation, and no biologic, adalimumab included, reliably closes them once they exist — that is a mechanical problem a drug alone doesn't fix.

What to Expect Starting Adalimumab

Because adalimumab works on an immune pathway rather than treating symptoms directly, response is usually judged at a defined checkpoint rather than day to day — in the trials that led to approval, that checkpoint was twelve weeks 2. A dermatologist experienced with HS is the one who weighs whether the disease has calmed enough to continue, whether the treatment plan needs to change, and whether any tunnels that have already formed still need a procedural or surgical fix that a biologic alone won't provide 3. Bloodwork and infection screening before and during treatment are standard practice for this drug class generally, and the specifics are worth asking your prescriber about directly rather than assuming they're identical for everyone.

Common questions

No. It's typically considered after topical and oral treatments — antiseptic washes, topical or oral antibiotics, and sometimes hormonal therapy — haven't controlled the disease, or when HS is more extensive from the start. Staging guides that decision; adalimumab generally enters the picture for more extensive disease rather than the mildest cases.

In the trials that led to its approval, significantly more people on adalimumab had a meaningful drop in inflamed lesions by twelve weeks than people on placebo. Not everyone who tries it responds, and response is typically judged at a defined checkpoint rather than assumed, which is why follow-up with a dermatologist matters as much as starting the drug itself.

Not on its own. Adalimumab works on active inflammation — new nodules and abscesses — rather than reversing tunnels or scarring that have already built up under the skin. Established tunnels more often need a procedural or surgical approach, sometimes alongside a biologic rather than instead of one.

HS can break through a biologic that worked initially, or someone may not respond to begin with. Newer biologics targeting a different inflammatory pathway are now an option that didn't exist when adalimumab was the only approved HS biologic, and switching drug classes is often more useful than simply stopping treatment.

No — adalimumab is a TNF-alpha inhibitor also used for psoriasis and other inflammatory conditions. It was approved for HS specifically only after its own dedicated trials, since a drug's success treating one inflammatory disease doesn't automatically predict success in another.

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When Hidradenitis Suppurativa Needs Prompt Attention

  • —Spreading redness, warmth, or fever around an HS lesion, which can signal a deeper bacterial infection rather than a typical flare
  • —A lesion that is rapidly swelling, intensely painful, or draining foul-smelling pus alongside chills
  • —New joint pain or swelling while on a biologic, which is worth reporting promptly rather than waiting for the next scheduled visit
  • —Any sign of a serious infection while on a biologic, such as a persistent fever or an infection that isn't improving

Spreading redness with fever, or any sign of a serious infection while on a biologic, warrants same-day medical attention — urgent care, or the ER if symptoms are severe or rapidly worsening.

This article is general health information, not medical advice. It cannot tell you whether adalimumab is right for your HS or replace an in-person evaluation by a dermatologist. Decisions about starting, continuing, or switching a biologic should be made with the clinician managing your care.

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References

  1. 1.Sabat R, Jemec GBE, Matusiak Ł, et al. (2020). Hidradenitis suppurativa. Nature Reviews Disease Primers. doi:10.1038/s41572-020-0149-1 ✓Hidradenitis suppurativa is a chronic inflammatory disease with follicular/immune pathophysiology producing nodules, abscesses, and tunnels, driven by immune activity rather than hygiene; background for TNF-alpha's role as an inflammatory mediator in the disease.
  2. 2.Kimball AB, Okun MM, Williams DA, et al. (2016). Two Phase 3 Trials of Adalimumab for Hidradenitis Suppurativa. New England Journal of Medicine. doi:10.1056/NEJMoa1504370The PIONEER I and II phase 3 placebo-controlled trials found weekly adalimumab significantly increased clinical response at week 12 in moderate-to-severe hidradenitis suppurativa, forming the basis for the first biologic indication in HS.
  3. 3.Alikhan A, Sayed C, Alavi A, et al. (2019). North American clinical management guidelines for hidradenitis suppurativa: Part I: Diagnosis, evaluation, and the use of complementary and procedural management. Journal of the American Academy of Dermatology. doi:10.1016/j.jaad.2019.02.067North American HS guideline on severity staging and evaluation, and on complementary/procedural (surgical) management for tunnels and disease not controlled by medical therapy alone.

3 sources, numbered by first appearance. General health information, not medical advice. AI-assisted editorial content — citations link their sources. Editorial policy

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