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Allen KamravaMD · MBA · FACS · FASCRS

Why do I get pimples on my butt?

In otherwise healthy people, what are the causes of recurrent papules and pustules on the buttocks (e.g., folliculitis, acne mechanica, keratosis pilaris), and how do their clinical features and risk factors differ?

How people search for this, in their own words

  • “why do i get pimples on my butt”
  • “why do i keep getting pimples on my butt”
  • “why do i have so many pimples on my butt”
  • “can you get a pimple in your butt crack”

Evidence review in plain language · compiled 2026-10-26 · checked 2026-10-26 · next 2026-11-26 · automated review, how it works

What the evidence says

Bottom line

Why pimples appear on the buttocks has barely been studied, but the few studies available point to two distinct, unrelated causes: a bacterial folliculitis linked to contaminated pool or hot-tub water, and keratosis pilaris, a common condition in which hair follicles get clogged with skin cells.

In one outbreak investigation, 25 of 40 adults who swam or soaked in under-chlorinated pool or whirlpool water developed itchy, pus-filled bumps on the buttocks (and armpits and limbs) within 2-4 days, and cultures grew Pseudomonas bacteria; this describes a specific contaminated-water exposure, not buttock pimples in general. Separately, case reports and a dermatologist survey describe keratosis pilaris, a harmless hereditary condition, as commonly affecting the buttocks with small rough bumps. The rest of the available evidence is single case reports of rare look-alike skin diseases, so this page cannot say how often each cause explains buttock pimples overall.

How well studied

Some evidence

Answered by 1 study following patients over time, of limited size or quality.

This question asks why something happens, not whether a treatment works, so there is no benefit-or-harm verdict. What can be shown is how well it has been studied.

answers it directly
1answers it directly
studies found
10studies found
randomised trials
0randomised trials
people studied
49people studied
years covered
2012–2024years covered

What the research shows

  • Proportion of cases due to bacterial folliculitis vs fungal folliculitis vs acne mechanica vs keratosis pilaris

    No study compared these causes side by side in a group of people with buttock pimples. The evidence is a mix of case reports of individual rare conditions and one survey about keratosis pilaris, which cannot show how common each cause is.[1,2,3,4,5,6,7,8,9]

    Too little evidence

  • Association with sweating, friction, tight clothing, or prolonged sitting

    None of the identified studies measured whether sweat, friction, tight clothes, or sitting for long periods made buttock pimples more likely.

    Not studied

  • Recurrence rate over time

    The one study that followed more than one person tracked symptoms only for days after pool exposure, not long-term recurrence. A separate case series noted no recurrence in three tumor-like lesions after removal, but this does not describe ordinary pimples.[1,2]

    Too little evidence

  • Response to topical antibacterial or antifungal treatment as a diagnostic clue

    No study tested whether a bump clearing up with antibacterial or antifungal cream could help tell apart the different causes.

    Not studied

  • Association with shaving or hair removal of the area

    No study looked at whether shaving or other hair removal of the buttock area was linked to developing these bumps.

    Not studied

What the studies found

  • In an outbreak investigation, 25 of 40 people exposed to under-chlorinated pool or whirlpool water developed itchy, pus-filled bumps on the buttocks, armpits, and limbs; skin cultures confirmed a bacterial infection called Pseudomonas folliculitis.[1]
  • Keratosis pilaris, a common and usually harmless condition caused by clogged hair follicles, is well documented as a cause of small rough bumps on the buttocks in both a dermatologist survey and individual case reports.[1,2]
  • Case reports show that persistent bumps that look like pimples but don't resolve can sometimes turn out to be rarer skin conditions (such as porokeratosis ptychotropica, Kyrle disease, or a benign follicular tumor), which were only correctly identified after a skin biopsy.[1,2,3,4,5,6,7]

Important limitations

  • Only one study looked at more than a single person — a 40-person outbreak report — and it was a descriptive investigation, not a study designed to compare causes.[1]
  • Eight of the ten studies found are single-patient case reports of rare conditions, which can tell us these conditions exist but cannot say how often they explain buttock pimples in otherwise healthy people.[1,2,3,4,5,6,7,8]

What kind of studies

  • Case series8 · 80%
  • Retrospective2 · 20%

The key studies

  • Huang et al. 2024

    Proliferating inverted follicular keratosis of genital skin: Case series of a challenging variant

    Describes a rare benign tumor, not ordinary pimplesCase seriesLow qualityRelated question

    4 people2024

    The lesions were a benign variant of a follicular tumor (proliferating inverted follicular keratosis), not squamous cell carcinoma, based on tissue and lab testing, and none recurred in the three cases with follow-up.

    Who was studied
    young women with a single lesion on the vulva, perineum, or inner buttock
    Main outcome
    whether these genital/buttock skin lesions were a benign tumor or skin cancer
    Quality
    This is a tiny case series of only 4 patients describing a rare benign tumor, not a study of common buttock pimples, so it offers very limited and indirect evidence for the question asked.
    Limitations
    Only 4 cases, no comparison group, describes a rare distinct tumor rather than typical acne-like pimples, and findings may not generalize to common causes of buttock pimples.

    Taken word for word from the abstract

    • population All patients were young women who presented with a solitary 0.5-1.0 cm lesion on the vulva, perineum, or inner buttock.
    • primaryOutcome with some characteristics of IFK but also atypical features, raising concern for squamous cell carcinoma (SCC)
    • result The absence of infiltrative growth or significant pleomorphism, the presence of numerous squamous eddies, the reassuring immunoprofile, and the lack of evidence of recurrence support a variant of IFK and speak against SCC.
    • n Four such tumors were identified in our database.

    J Cutan Pathol · PMID 38736174 · Read it on PubMed ↗

  • Greenzaid et al. 2023

    Keratosis Pilaris: Treatment Practices of Board-Certified Dermatologists

    Clogged, inflamed hair follicles cause itRetrospectiveLow qualityRelated question

    size not given2023

    The abstract describes keratosis pilaris as a chronic disorder of clogged, inflamed hair follicles with perifollicular redness, causing papules on the arms, upper legs, and buttocks; the rest of the study reports on dermatologists' treatment habits rather than the cause itself

    Who was studied
    Dermatologists surveyed about patients with keratosis pilaris, a condition causing small bumps on the arms, legs, and buttocks
    Main outcome
    What causes the bumps of keratosis pilaris and where they occur
    Quality
    This is a survey of dermatologists about which treatments they use, not a study designed to investigate why these bumps occur on the buttocks.
    Limitations
    It is a physician opinion survey about treatment practices, not a study of disease cause, lesion biopsy, or patient-level data; no participant count is given.

    Taken word for word from the abstract

    • population lesions affecting the extensor surfaces of arms, upper legs, and buttocks
    • result Keratosis pilaris (KP) is a chronic disorder of follicular hyperkeratinization and perifollicular erythema with lesions affecting the extensor surfaces of arms, upper legs, and buttocks.
    • primaryOutcome Keratosis pilaris (KP) is a chronic disorder of follicular hyperkeratinization and perifollicular erythema with lesions affecting the extensor surfaces of arms, upper legs, and buttocks.

    J Drugs Dermatol · PMID 37801530 · Read it on PubMed ↗

  • Hoang et al. 2020

    Porokeratosis ptychotropica: a rare variant that is commonly misdiagnosed

    Rare mimic condition, often misdiagnosed as pimplesCase seriesVery low qualityRelated question

    size not given2020

    The bumps were actually a rare skin condition called porokeratosis ptychotropica, which looks like pimples or other common skin problems but is often misdiagnosed for years

    Who was studied
    A person with itchy, scaly bumps and patches on the skin around the anus and buttock crease
    Main outcome
    What causes these perianal/gluteal bumps and why they are misdiagnosed
    Quality
    This is a single case report, so it cannot show how common this cause of buttock bumps actually is.
    Limitations
    Only one patient described; no information on how frequently this condition explains buttock pimples in the general population.

    Taken word for word from the abstract

    • population characterized by pruritic, scaly papules and plaques localized to the perianal and gluteal cleft regions
    • primaryOutcome Clinically, PP resembles other common disorders, resulting in frequent misdiagnosis
    • result We report a case of PP diagnosed at an early stage.
    • n We report a case of PP diagnosed at an early stage.

    Dermatol Online J · PMID 32815698 · Read it on PubMed ↗

  • Zhu et al. 2014

    Unilateral generalized keratosis pilaris following pregnancy

    Clogged hair follicles (keratosis pilaris), not infection.Case seriesVery low qualityRelated question

    1 people2014

    The bumps were caused by keratosis pilaris, a common inherited hair-follicle condition that can appear on the buttocks, and in this case may have been worsened by pregnancy hormones and a genetic mutation.

    Who was studied
    a 29-year-old pregnant woman with a generalized skin condition
    Main outcome
    cause of small raised bumps on the buttocks and other areas
    Quality
    This is a single case report of one person, so it cannot show how common this cause is in general.
    Limitations
    Only one patient was studied, and the case involved an unusual pregnancy-related, one-sided presentation rather than typical buttock pimples.

    Taken word for word from the abstract

    • population a 29-year-old woman with unilateral generalized KP in the second month of her second pregnancy
    • primaryOutcome small folliculocentric keratotic papules that may have surrounding erythema
    • intervention The extensor surfaces of the upper arms, thighs, and buttocks commonly are affected
    • result Both a genetic mutation and pregnancy-induced hormonal changes played possible roles in the development and progress of unilateral generalized KP in this patient.
    • n a 29-year-old woman

    Cutis · PMID 25372256 · Read it on PubMed ↗

  • Cohen-Dar et al. 2012

    [Pseudomonas folliculitis outbreaks associated with swimming pools or whirlpools in two guest-room sites in the northern region of Israel]

    Pimples from contaminated pool/whirlpool water.RetrospectiveLow quality

    40 people2012

    Of 40 bathers exposed to under-chlorinated pools/whirlpools, 25 (62.5%) developed Pseudomonas folliculitis 2-4 days later, with the rash typically starting as itchy red papules on the buttocks, armpits and limbs, along with fever, swollen glands and outer ear infection; cultures of the pustules grew Pseudomonas aeruginosa

    Who was studied
    Adults who swam in or used whirlpools/swimming pools at guest-room sites
    Main outcome
    Development of itchy pimple-like rash (folliculitis) after pool/whirlpool exposure
    Quality
    This is a descriptive outbreak investigation without a control group, so it shows an association but cannot rule out other contributing factors.
    Limitations
    Descriptive outbreak report, no comparison group, relies on exposure history and culture results from two specific outbreak sites.

    Taken word for word from the abstract

    • population Of 40 bathers, 25 (62.5%) developed Pseudomonas folliculitis 2-4 days after exposure.
    • primaryOutcome Typically the rash began as a pruritic erythematous papule on the buttocks, axilla, and extremities, with fever, adenopathy and otitis externa.
    • result In the culture of the pustules and bacterial examination grew Pseudomonas aeroginosa.
    • result The source of the infection was traced to the swimming pools or whirlpools, which had not been chlorinated and monitored routinely.
    • n Of 40 bathers, 25 (62.5%) developed Pseudomonas folliculitis 2-4 days after exposure.

    Harefuah · PMID 23002686 · Read it on PubMed ↗

All 10 studiesEvery study that answered the question, with its design, size and result.
The other 5 studiesEverything else the search returned, including anything retracted.

  • Brusasco et al. 2024

    A Case of Noonan Syndrome and Kyrle's Disease: Coincidence or Causality?

    Rare disease, not typical pimples.Case seriesVery low qualityRelated question

    1 people2024

    The lesions were diagnosed as Kyrle's disease, a rare perforating skin disorder usually linked to chronic kidney failure or diabetes, with lesions typically appearing on the limbs and buttocks; in this patient no such disease was found, and it may instead be related to her genetic syndrome

    Who was studied
    a 39-year-old woman with Noonan Syndrome, not the general population of adolescents/adults without immunosuppression
    Main outcome
    identifying the cause of umbilicated, keratotic papules (a condition called Kyrle's disease)
    Quality
    This is a single case report about a rare genetic syndrome, not a representative study of why healthy people get buttock pimples.
    Limitations
    Single patient case report; the patient has a rare genetic condition (Noonan Syndrome) and her lesions were on the limbs, not the buttocks; this does not describe typical pimples in healthy adolescents/adults.

    Taken word for word from the abstract

    • n A 39-year-old Caucasian woman affected by Noonan Syndrome (NS) mutated in RAF1 was referred to us
    • population A 39-year-old Caucasian woman affected by Noonan Syndrome (NS) mutated in RAF1 was referred to us with itchy lesions on her limbs
    • primaryOutcome A final diagnosis of Kyrle's disease (KD) was established.
    • result The typical skin manifestation of KD is an eruption of dome-shaped papules and nodules with a whitish central keratotic plug, mainly localized on the extremities and the buttocks.
    • result KD is frequently associated with systemic diseases, especially chronic renal failure and diabetes mellitus.
    • result In our patient, we ruled out all the causes commonly associated with KD.

    Acta Dermatovenerol Croat · PMID 38946190 · Read it on PubMed ↗

  • Brusasco et al. 2023

    A Case of Noonan Syndrome and Kyrle Disease: Casualty or Causality?

    Rare disease, not a typical cause.Case seriesVery low qualityRelated question

    1 people2023

    This case report describes 'Kyrle disease,' a rare skin condition causing umbilicated papules with a hard central plug, typically linked to diabetes or kidney failure; it is usually found on the limbs and buttocks, but in this specific patient the lesions were only on the arms and legs, not the buttocks. The authors speculate a possible link to her underlying Noonan Syndrome.

    Who was studied
    A 39-year-old woman with Noonan Syndrome (a rare genetic condition), not the general population of adolescents/adults asked about
    Main outcome
    Cause of skin bumps/pimple-like lesions and their treatment
    Quality
    A single rare case report cannot establish why typical pimples occur on the buttocks in the general population.
    Limitations
    Only one patient, with a rare genetic syndrome, and the lesions described were not actually located on the buttocks in this case; causation with Noonan Syndrome is speculative.

    Taken word for word from the abstract

    • n A 39-year-old Caucasian woman affected by Noonan Syndrome (NS) mutated in RAF1 was referred to us with itchy lesions on her limbs that had appeared two months earlier.
    • population A 39-year-old Caucasian woman affected by Noonan Syndrome (NS) mutated in RAF1
    • primaryOutcome A final diagnosis of Kyrle disease (KD) was established.
    • result The typical skin manifestation of KD is an eruption of dome-shaped papules and nodules, with a whitish central keratotic plug, mainly localized on the extremities and the buttocks.
    • result Clinically, there were multiple umbilicated papules with a hyperkeratotic central plug, localized on the upper and lower limbs
    • result it will be necessary to collect additional data to confirm this hypothesis

    Acta Dermatovenerol Croat · PMID 38439730 · Read it on PubMed ↗

  • Xiao et al. 2022

    An unusual case report of porokeratosis ptychotropica on the buttocks

    Rare skin disease mimicking pimplesCase seriesVery low qualityRelated question

    1 people7 years (duration of symptoms before diagnosis)

    The bumps were actually a rare skin condition called porokeratosis ptychotropica, not ordinary pimples, confirmed by skin exam and biopsy

    Who was studied
    A 33-year-old man with itching papules and plaques on the buttocks for 7 years
    Main outcome
    What is causing the pimple-like bumps on the buttocks
    Quality
    This is a single patient case report, so it cannot tell us how common this cause is or whether it applies to most people with buttock pimples.
    Limitations
    Only one patient; this is a rare, specific skin disease rather than the common cause of pimples on the buttocks; findings may not generalize.

    Taken word for word from the abstract

    • population A 33-year-old man, who complained of itching papules and plaques in the gluteal cleft and the buttocks for the last 7 years.
    • primaryOutcome he was diagnosed with porokeratosis ptychotropica
    • result Dermoscopy and histopathological findings were consistent with porokeratosis.
    • n A 33-year-old man

    Medicine (Baltimore) · PMID 36451470 · Read it on PubMed ↗

  • Dogan et al. 2017

    Childhood-Onset Keratosis Lichenoides Chronica Accompanied by Severe Hair Loss

    Rare skin disease, not ordinary pimplesCase seriesVery low qualityRelated question

    1 people2017

    The buttock lesions were flat-topped, purple-to-brown hyperkeratotic lichenoid papules and linear plaques that were part of a rare condition called keratosis lichenoides chronica, confirmed by skin biopsy, not ordinary acne-type pimples

    Who was studied
    A 37-year-old woman with lifelong skin changes, not the typical adolescent/adult population with ordinary buttock pimples
    Main outcome
    What skin condition was causing hyperkeratotic papules and plaques, including on the buttocks
    Quality
    This is a single unusual case report of a rare disease, so it tells us almost nothing about why typical people get pimples on the buttocks.
    Limitations
    Single case report of a rare genodermatosis (keratosis lichenoides chronica) with associated hair loss, not representative of common causes of buttock pimples in otherwise healthy people.

    Taken word for word from the abstract

    • population A 37-year-old woman attended the dermatology outpatient clinic because of recent hair loss from the eyebrows and axillae.
    • n A 37-year-old woman attended the dermatology outpatient clinic
    • primaryOutcome Clinicopathologic correlation of the case was consistent with keratosis lichenoides chronica (KLC).
    • result flat-topped, purple to brown hyperkeratotic lichenoid papules and linear plaques on the elbows, trunk, and buttocks

    Skinmed · PMID 28705285 · Read it on PubMed ↗

  • Cabete et al. 2015

    Porokeratosis ptychotropica of the scrotum: dermoscopic evaluation of an atypical presentation

    Rare skin condition, not common pimples.Case seriesVery low qualityRelated question

    size not given2015

    This case describes porokeratosis ptychotropica, a rare skin condition usually found on the buttocks and perianal area, which can look unusual when it extends to the genitals; dermoscopy helps tell it apart from other genital skin problems, but biopsy showing specific tissue changes (cornoid lamellae) remains the definitive way to diagnose it

    Who was studied
    A person with an unusual case of a skin condition on the scrotum (porokeratosis ptychotropica), a rare variant typically affecting the buttock and perianal area
    Main outcome
    What this bump-like skin condition is and how to recognize it using skin examination tools (dermoscopy) versus tissue biopsy
    Quality
    This is a single case report, which only describes one unusual instance and cannot show how common or typical this cause of buttock bumps is.
    Limitations
    Single case report of an atypical presentation; findings may not generalize to typical buttock pimples, and the case focuses on the scrotum rather than the buttocks themselves.

    Taken word for word from the abstract

    • population Porokeratosis ptychotropica is a rare variant of porokeratosis that is classically located on the gluteal and perianal regions, seldom extending to the genitalia.
    • primaryOutcome discuss the use of dermoscopy in evaluating this dermatosis
    • result Dermoscopic findings, although not specific to this variant of porokeratosis, are helpful in the differential diagnosis of other genital disorders. Histopathology, through the visualization of multiple cornoid lamellae, prevails as the gold standard for the definite diagnosis of porokeratosis ptychotropica.

    An Bras Dermatol · PMID 26312713 · Read it on PubMed ↗

How we searchedThe exact query, the date it ran, and what came back — so you can run it yourself.
Searched
PubMed · ClinicalTrials.gov · Crossref on 2026-10-26
The exact search — paste this into PubMed to repeat it
("Folliculitis"[Mesh] OR "Furunculosis"[Mesh] OR "Acne Vulgaris"[Mesh] OR "Keratosis"[Mesh] OR "Hidradenitis Suppurativa"[Mesh]) AND (buttock*[tiab] OR gluteal[tiab] OR gluteus[tiab])
PubMed expanded that to: ("Folliculitis"[MeSH Terms] OR "Furunculosis"[MeSH Terms] OR "Acne Vulgaris"[MeSH Terms] OR "Keratosis"[MeSH Terms] OR "Hidradenitis Suppurativa"[MeSH Terms]) AND ("buttock*"[Title/Abstract] OR "gluteal"[Title/Abstract] OR "gluteus"[Title/Abstract])
What came back
315 records found · 200 read · 10 answered the question
Included
  • Human, animal or laboratory studies reporting an outcome relevant to the question
Excluded
  • Records about a different condition or intervention
  • Studies mainly about Hidradenitis suppurativa (recurrent abscesses in skin folds)
  • Studies mainly about Pilonidal cyst/sinus (midline sacrococcygeal cyst)
  • Studies mainly about Genital herpes (vesicular lesions)
  • Studies mainly about Molluscum contagiosum
  • Studies mainly about Scabies
  • Studies mainly about Boils from MRSA skin infection
  • Records reporting no outcome
  • Retracted publications, which are listed but excluded from every count
Limits
  • Details were read from abstracts, not full papers, so anything reported only in a paper's methods section is not captured here.
  • Fields were read from abstracts, not full text, so detail reported only in a paper's methods section is not captured.
  • Evidence strength is adapted from the GRADE framework. It is not a GRADE assessment and was not produced by a GRADE panel.

Automated evidence review — PubMed, ClinicalTrials.gov, Crossref. Search strategy, grading rules and the checks that must pass before anything publishes were written by Allen Kamrava, MD, MBA, FACS, FASCRS, colon & rectal surgery, Beverly Hills. The pages themselves are compiled by software running that method and are not read one by one before publication — saying otherwise would be the one claim here that could not be checked.

How we grade evidence →

  1. 315records came back from the search
  2. 200were read
  3. 10actually answered the question
Risks and safetyReported side effects and who should be careful.
  • In the pool and whirlpool outbreak, the folliculitis sometimes came with fever, swollen glands, and an outer-ear infection, meaning the infection was not always limited to the skin.
  • One of the rarer look-alike conditions, porokeratosis ptychotropica, is described in case reports as easily confused with other common skin problems and often misdiagnosed; in one case the correct diagnosis wasn't reached until after 7 years of symptoms, when a skin exam and biopsy confirmed it.
Why people askWhat brings people to this question.
  • Bumps on the buttocks are embarrassing and easy to mistake for facial acne, so people look for a quick explanation.
  • The bumps often keep coming back despite normal skincare, which is frustrating and makes people search for a specific cause.
  • Tight clothing, gym gear, and long periods of sitting are widely assumed culprits, so people want to know if that's really why.
  • After using a hot tub, pool, or sauna, a sudden breakout raises worry about hygiene or infection.
  • Itching or bumps near the buttock crease can raise worry about something more serious, prompting a search for reassurance.
Common questionsShort answers, drawn from the same studies.
Why do I get pimples on my butt?
The research found two main documented causes: a bacterial skin infection called folliculitis (sometimes linked to hot tubs or pools) and keratosis pilaris, a common harmless condition where hair follicles get clogged. Rare skin conditions can also look like pimples, but these are uncommon and need a skin exam to confirm.
Why do I keep getting pimples on my butt?
No study directly measured how often buttock pimples come back over time in otherwise healthy people. Conditions like keratosis pilaris are known to be chronic and can persist for years, which may explain repeated bumps, but this wasn't formally tracked in the studies found.
Why do I have so many pimples on my butt?
One documented cause of a sudden cluster of bumps is exposure to under-chlorinated pool or whirlpool water, which caused a bacterial folliculitis outbreak in most bathers exposed. No study looked at what causes many bumps to appear without that kind of exposure.
Can you get a pimple in your butt crack?
Yes — case reports describe pimple-like bumps occurring in the buttock crease and perianal area, though in some cases biopsy showed they were actually rare conditions rather than ordinary pimples. This has not been studied in large numbers of people.
When should I see a doctor about pimples on my butt?
See a doctor if the bumps come with fever or swollen glands, as seen in the pool-outbreak study, or if they don't go away, look unusual, or keep recurring despite basic care. Several case reports found that persistent bumps turned out to be other skin conditions only after a biopsy.
What has changedEvery re-check, and whether it changed the answer.

  1. 2026-10-26

    Clear the 'Under re-review' backlog: rebuild every remaining first-method (ev-1) page under the current method. 5 new studies · 115 no longer retrieved · evidence strength very low → low · conclusion signal of harm → not applicable.

    How certain we are changed. The conclusion changed.

This is information, not advice

This page summarises published research. It cannot tell you what is happening in your own body, and evidence changes. If something is bleeding, painful, or new, it is worth being looked at — that is a different question from the one on this page, and a better one to bring to a consultation.

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Automated evidence review — PubMed, ClinicalTrials.gov, Crossref. Search strategy, grading rules and the checks that must pass before anything publishes were written by Allen Kamrava, MD, MBA, FACS, FASCRS, colon & rectal surgery, Beverly Hills. The pages themselves are compiled by software running that method and are not read one by one before publication — saying otherwise would be the one claim here that could not be checked.

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