A buttock abscess forms when bacteria invade the skin or deeper tissue and trigger a walled-off pocket of pus. The most common culprit is Staphylococcus aureus, including drug-resistant strains like MRSA, but the buttock region is unusual in how often its abscesses involve multiple bacterial species at once. The reasons a person develops an abscess in this particular spot, rather than elsewhere, have as much to do with the anatomy and daily stresses the area endures as with the bacteria themselves.
Which Bacteria Are Involved
Skin abscesses anywhere on the body are most often caused by staph bacteria that live on the skin’s surface and find a way inside through a hair follicle, a small cut, or a microscopic break you never notice. On the buttocks and in the perianal region, though, the microbial picture is more complicated. A study of wound and abscess cultures found that the buttocks and inguinal area had the highest rates of anaerobic bacteria among all body sites, and that abscesses in these locations were frequently polymicrobial, meaning several species of bacteria were working together rather than a single one acting alone.1JAMA Surgery. Aerobic and Anaerobic Bacteriology of Wounds and Cutaneous Abscesses A review of polymicrobial abscess research confirmed that organisms from the gastrointestinal and cervical flora, including gut-associated bacteria like Bacteroides fragilis, were found most often in buttock and leg abscesses.2Journal of Antimicrobial Chemotherapy. Microbiology of polymicrobial abscesses and implications for therapy
That mix matters because it reflects the buttock’s proximity to the anus and the gastrointestinal tract. Bacteria that normally live harmlessly in the colon can seed an infection if they migrate into a break in the skin or a blocked gland. And MRSA, which has become a major player in skin infections over the past two decades, shows up in perianal abscesses at rates that surprise many clinicians. In one study of patients whose perianal abscesses were cultured at drainage, about a third tested positive for MRSA.3PubMed. MRSA-related perianal abscesses: an underrecognized disease entity That’s a meaningful number because MRSA doesn’t respond to many first-line antibiotics, which can change the treatment plan if antibiotics are needed after drainage.
Why the Buttocks Are Especially Vulnerable
Several features of the buttock region conspire to make abscesses more likely here than on, say, your forearm. The skin sits over a thick layer of fat and spends much of the day compressed against a chair. That sustained pressure and friction can irritate hair follicles and block sweat glands, giving bacteria an entry point. Moisture from sweat gets trapped in the gluteal cleft, creating a warm, damp environment where bacteria thrive. The dense hair that many people have in this area provides additional follicles that can become infected.
Then there’s the proximity to the anorectal canal. Tiny glands located inside the anal canal can become blocked and infected, producing what’s known as a cryptoglandular abscess. The infection starts in the space between the sphincter muscles and can track outward into the surrounding buttock tissue.4Revue Marocaine des Maladies Infections. Cryptoglandular anal abscesses: from diagnosis to treatment This is the most common pathway for perianal abscesses, and it explains why what feels like a painful lump on the outer buttock sometimes originates from deep inside the rectal area.
Risk Factors That Raise Your Chances
Anyone can develop a buttock abscess, but certain conditions tilt the odds. Diabetes is one of the most consistent risk factors. Poor blood sugar control weakens the immune response and slows wound healing, making it easier for small infections to escalate. Research tracking patients with type 1 and type 2 diabetes found that the risk of developing a perianal abscess climbed as blood sugar control worsened. Patients with diabetes-related complications like ketoacidosis had more than double the odds of developing one compared to people without diabetes.5PubMed Central. Risk for developing perianal abscess in type 1 and type 2 diabetes and the impact of poor glycemic control
Immunosuppression from any cause raises the risk. People taking immunosuppressive drugs for autoimmune diseases, organ transplant recipients, and those with blood disorders like myelodysplastic syndrome are all more susceptible to soft tissue infections. In immunocompromised patients, even organisms that rarely cause trouble in healthy people can form abscesses. One case involved a large subcutaneous abscess on the buttock caused by Trichophyton rubrum, a common fungus that usually causes nothing worse than athlete’s foot, but in a patient on long-term immunosuppressants it grew into a 15-centimeter cyst that had to be surgically removed.6Medical Mycology Journal. A Giant Dermatophyte Abscess Caused by Trichophyton rubrum in an Immunocompromised Patient Similarly, infections from atypical mycobacteria, organisms related to the tuberculosis germ, can present as nodules on the buttocks in otherwise healthy children.7PubMed. A pediatric case of atypical Mycobacterium avium infection of the skin
Immunocompromised patients also face the complication that their infections can mimic other conditions. A bruise from a simple intramuscular injection can become infected, and the resulting abscess can look like a soft tissue tumor on imaging. Pyomyositis, an infection of the muscle itself, is also more common in people with weakened immune systems or diabetes.8PubMed Central. Lesion mimicking perianal abscess in an immunocompromised patient: Report of a case
Other everyday risk factors include obesity, which increases skin friction and moisture; inflammatory bowel disease, particularly Crohn’s disease, which can cause perianal abscesses as a direct complication; and shaving or waxing the buttock area, which irritates hair follicles.
Abscesses Caused by Injections
Intramuscular injections in the buttock are a well-recognized cause of gluteal abscesses, and they deserve their own mention because they’re entirely preventable. The traditional dorsogluteal site (the upper outer quadrant of the buttock) has a thick fat pad, and if the needle is too short to reach muscle tissue, the medication is deposited into the fat layer instead. There it can irritate the tissue or create a sterile pocket that later becomes infected. A retrospective study of post-injection gluteal abscesses pointed to improper injection technique, inadequate aseptic precautions, and the mismatch between needle length and the patient’s fat pad as the primary contributors. Patient comorbidities like diabetes and immunosuppression compounded the risk.9Journal of Medical Sciences SKIMS. Gluteal abscess post intramuscular Injection: A Retrospective Study
This is one reason many healthcare guidelines now favor the ventrogluteal site (the side of the hip) over the dorsogluteal site for intramuscular injections. The ventrogluteal area has less subcutaneous fat, fewer major nerves and blood vessels, and a more predictable anatomy. If you’re receiving regular injections and they’re going into the upper buttock, it’s worth asking your provider about the injection site.
How Doctors Tell It’s an Abscess
Most buttock abscesses are diagnosed by physical examination alone. You’ll typically see a firm, swollen, red, and exquisitely tender lump. The skin over it may feel warm, and if it’s close to the surface, you might notice a soft spot or a yellowish point where pus is close to breaking through.
When the diagnosis is less clear, particularly if the lump is deep or the patient has unusual symptoms, bedside ultrasound is the go-to tool. Ultrasound can differentiate between an abscess that needs drainage and simple cellulitis (a diffuse skin infection) that may respond to antibiotics alone.10PubMed. Ultrasound features of purulent skin and soft tissue infection without abscess On ultrasound, an abscess shows up as a dark, fluid-filled pocket, sometimes with visible internal debris or gas. Pressing the probe against the area can make the fluid swirl, confirming that it’s liquid pus rather than solid tissue.11Journal of Education and Teaching in Emergency Medicine. Point-of-care Ultrasound for the Diagnosis of a Gluteal Abscess In a pediatric emergency department study, bedside ultrasound performed by trained physicians detected abscesses with a sensitivity of about 97%, meaning it catches nearly all of them.12PubMed. The effect of bedside ultrasound on diagnosis and management of soft tissue infections in a pediatric ED
For deeper abscesses, particularly perianal ones that may extend into the spaces around the rectum, CT or MRI can map the full extent of the infection. This matters because an abscess that tunnels through muscle planes can form connections to the anal canal, which affects the surgical approach.
Treatment and What to Expect
The core treatment for any abscess is drainage. Antibiotics alone can’t reliably clear a walled-off collection of pus because the drug can’t penetrate the abscess cavity well enough. The standard procedure, called incision and drainage, involves numbing the area with local anesthesia, making a cut, evacuating the pus, and sometimes packing the wound with gauze to keep it open so it can heal from the inside out.
Whether you also need antibiotics after drainage depends on the situation. For a straightforward, small abscess in an otherwise healthy person, drainage alone is often sufficient. But evidence suggests that oral antibiotics after drainage can improve outcomes in certain cases, particularly when the surrounding skin is significantly inflamed, when the patient has a fever or other systemic signs, or when MRSA is suspected or confirmed.13PubMed. Abscess Management: An Evidence-Based Review for Emergency Medicine Clinicians The decision to prescribe antibiotics involves weighing the benefit against risks like antibiotic side effects and the promotion of resistant bacteria.
After drainage, you’ll typically need to keep the wound clean, change dressings regularly, and may need follow-up visits. Perianal abscesses that are deep or complex often require drainage under general anesthesia in an operating room rather than a bedside procedure.
When an Abscess Leads to More Problems
An abscess that isn’t drained promptly, or one that drains but doesn’t fully resolve, can cause complications. Prolonged infection weakens the surrounding muscle through inflammatory swelling and can allow the infection to spread into the subcutaneous tissue of the buttock. In perianal cases, this process can lead to the formation of an anal fistula, an abnormal tunnel connecting the inside of the anal canal to the skin surface.14PubMed Central. Extrasphincteric anal fistula with gluteal extension: A case report and literature review Fistulas are notoriously difficult to treat and often require specialized surgery. Roughly a third or more of perianal abscesses go on to develop a fistula, which is one reason surgeons take these infections seriously even when the abscess itself seems small.
In rare cases, especially in immunocompromised patients, an untreated buttock abscess can spread to deeper compartments, potentially reaching the pelvic floor or causing sepsis. These severe complications are uncommon with timely treatment but underscore why you shouldn’t try to wait out a painful, enlarging lump on your buttock.
Why Some People Keep Getting Them
Recurrence is frustratingly common with buttock abscesses. Part of the problem is Staphylococcus aureus colonization. Many people carry staph bacteria in their nostrils, on their skin, or in the groin without any symptoms. This colonization acts as a reservoir, and decolonization (using nasal antibiotic ointment and antiseptic body washes) is often recommended for people with recurrent skin infections. Critically, staph infections tend to cluster within households, and household members who are asymptomatic carriers can keep re-introducing the bacteria. Research suggests that a household-wide approach to decolonization is more effective than having only the affected person do it.15PubMed Central. Prevention of Recurrent Staphylococcal Skin Infections
The evidence on decolonization’s long-term effectiveness is mixed, however. A review of recurrence strategies found that MRSA decolonization showed some benefit but also long-term loss of effectiveness and possible side effects.16PubMed Central. Recurrence of skin and soft tissue infections: identifying risk factors and treatment strategies And a pediatric study looking specifically at MRSA abscess recurrence found that patients who underwent decolonization protocols did not have lower recurrence rates than those who didn’t, even in high-risk groups like those with a personal or family history of MRSA infection.17PubMed Central. Impact of Decolonization Protocols and Recurrence in Pediatric MRSA Skin and Soft-Tissue Infections
So decolonization is reasonable to try, especially when infections are bouncing around a household, but it’s not a guaranteed fix. Addressing modifiable risk factors like blood sugar control in diabetes, weight management, and hygiene practices in the gluteal area may be just as important for breaking the cycle.
Conditions That Look Like an Abscess but Aren’t Quite
Not every painful lump on the buttock is a straightforward bacterial abscess. Several other conditions can produce swelling, redness, and even draining pus in the same area, and getting the diagnosis wrong can lead to the wrong treatment.
Hidradenitis suppurativa is the most important mimic. It’s a chronic inflammatory disease that targets areas with apocrine sweat glands, including the buttocks, groin, and armpits. It produces recurrent painful nodules and abscesses that can rupture, form tunnels beneath the skin (sinus tracts), and leave scarring.18PubMed Central. Magnetic Resonance Imaging of Hidradenitis Suppurativa: A Focus on the Anoperineal Location The underlying problem in hidradenitis suppurativa is occlusion and inflammation of the apocrine glands, not a primary bacterial infection, though bacteria often colonize the lesions secondarily.19PubMed Central. Gluteal and perianal hidradenitis suppurativa associated with tuberulosis If you’ve had multiple “abscesses” in the groin, buttocks, or underarms that keep coming back despite proper drainage, hidradenitis suppurativa is worth discussing with a dermatologist. The treatment is fundamentally different, relying on immunomodulators, biologics, or specialized surgery rather than simple incision and drainage.
Long-standing hidradenitis suppurativa also carries a rare but real risk of malignant transformation. Patients who have had the disease for a decade or longer can develop tumors in the affected tissue, most commonly squamous cell carcinoma but occasionally mucinous adenocarcinoma.20PubMed Central. Mucinous adenocarcinoma of the buttock associated with hidradenitis: A case report These tumors can masquerade as yet another flare-up of the underlying disease, which is one reason chronic or changing lesions should be evaluated carefully.
Pyoderma gangrenosum is another condition that can be misdiagnosed as an abscess. It causes painful, rapidly enlarging ulcers that look infected but are actually driven by a dysfunctional immune response. Surgery makes it worse rather than better. In a case series of 12 patients with pyoderma gangrenosum, five underwent surgical procedures before the correct diagnosis was made, and all five experienced prolonged worsening of their disease before eventually responding to appropriate medical treatment.21The American Surgeon™. A Retrospective Study of 12 Cases of Pyoderma Gangrenosion: Why We Should Avoid Surgical Intervention and What Therapy to Apply The lesson is that a wound on the buttock that keeps getting worse after drainage, or that doesn’t behave like a typical healing abscess, deserves a second look from a specialist.
Pilonidal Disease
One of the most common reasons young adults end up in the emergency room with a buttock abscess is pilonidal disease. A pilonidal cyst forms in the natal cleft (the crease between the buttocks), usually at or just above the tailbone. The prevailing theory is that loose hairs get driven into the skin by friction and pressure, creating a foreign-body reaction that can become infected. When that happens, the result is a pilonidal abscess: a hot, swollen, intensely painful lump right at the top of the gluteal cleft.
Pilonidal disease is especially common in young men with coarse body hair and in people who spend long periods sitting. It was famously called “jeep driver’s disease” during World War II because of how often it appeared in soldiers who bounced around in military vehicles for hours. The acute abscess is treated with drainage, but the underlying cyst tends to recur unless the sinus tract and any associated pits in the skin are addressed. Treatment options range from simple excision to more elaborate surgical techniques like cleft-lift procedures that reshape the natal cleft to reduce recurrence.
Pilonidal abscesses are distinct from the other causes discussed above in that the infection is driven by trapped hair and debris rather than by a nearby body flora or a blocked gland. That said, once a pilonidal sinus becomes infected, the same bacteria show up: staph, strep, and often the anaerobic gut organisms that colonize the area.
When to Seek Medical Attention
Small boils on the buttock sometimes resolve on their own or with warm compresses. But you should see a clinician if the lump is larger than a couple of centimeters, is growing rapidly, comes with fever or chills, or causes pain severe enough to interfere with sitting. A lump near the anus that is accompanied by pain during bowel movements may be a perianal abscess extending into deeper spaces, and these almost always require professional drainage.
You should also seek evaluation if you notice a pattern. A single abscess is common and usually uncomplicated. But recurring lumps in the buttock, groin, or armpit area may point to an underlying condition like hidradenitis suppurativa, uncontrolled diabetes, or chronic staph carriage that needs a broader treatment strategy rather than repeated trips to the emergency department for drainage.