Buttock Acne: What Causes It? A Dermatologist's 9 Types: Folliculitis, Keratosis Pilaris, Boils, Bumps Near the Anus, Which Creams to Use, and Will Dark Buttocks Fade?

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Buttock acne is mostly not true acne like the kind on the face. It is usually folliculitis, an inflammation or infection at the opening of the hair follicle, most often caused by Staphylococcus aureus bacteria together with sweat, trapped moisture, and friction from prolonged sitting or tight clothing. Other bumps on the buttocks are usually keratosis pilaris, fungal acne, boils, or conditions specific to the area, such as hidradenitis suppurativa and pilonidal cysts.

Telling them apart before choosing a treatment matters a great deal, because many facial acne medicines do not help folliculitis or fungal acne, and some bumps on the buttocks or near the anus need a doctor to drain the pus or operate rather than self-applied creams. This article separates buttock bumps into 9 types, with their appearance, causes, urgency, and the medicines doctors usually choose for each.

What Is Buttock Acne, and Why Do Bumps Appear Easily There?

The skin on the buttocks has far fewer oil glands than the face and back, so true acne caused by blocked oil glands is uncommon there. What makes the buttocks prone to bumps is the environment of the skin in this area.

Prolonged sitting and pressure: Sitting 8–10 hours a day at work, driving, or studying keeps the skin pressed and trapped without airflow. Follicle openings swell and block easily. The related search “sitting a long time, acne” has some truth to it.
Sweat, heat, and humidity: Thailand is hot and humid almost all year. Skin that stays damp with sweat for long periods is an environment where bacteria and yeast on the skin multiply easily.
Friction: Tight pants, jeans, synthetic workout wear, underwear with tight elastic edges, and cycling.
Hair removal: Shaving, waxing, or plucking hair on the buttocks and groin causes tiny wounds at the follicle openings and ingrown hairs that curl back into the skin.
Dry, rough skin: Dead skin blocks the follicle openings and causes keratosis pilaris, which is common in people with dry skin or atopic dermatitis.

Quick Check: Which Type Are Your Buttock Bumps Likely to Be?

Look at the bumps against this list before buying a medicine to apply yourself.

Small red bumps or small pus bumps, 2–5 mm, with a hair in the center, slightly painful, appearing from time to time → bacterial folliculitis
Blocked bumps and red bumps only where you sit or where waistbands are tight → pressure and friction acne
Tiny rough bumps, 1–2 mm, skin like goose skin, rarely painful, also on the backs of the thighs and upper arms → keratosis pilaris
Small bumps of equal size that itch, appearing dozens at a time and flaring after sweating → fungal acne
Red itchy bumps appearing 1–2 days after a hot tub or swimming pool → hot tub folliculitis
A very painful, red, hot lump of 1 cm or more with pus in the center → boil
Painful lumps that keep coming back in the buttock crease, groin, or around the anus, with draining tracts and scars that connect → hidradenitis suppurativa
A painful swollen lump in the middle of the buttock crease above the tailbone, possibly with a tiny hole and a hair sticking out → pilonidal cyst
Acne-like bumps at the edge of the anus, itchy, or painful during bowel movements → need to rule out perianal dermatitis, warts, herpes, and perianal abscess

If your bumps fit several items, or you are not sure, treat it as something a doctor should see first, especially items 6–9.

1. Bacterial Folliculitis

This is the most common cause of buttock acne in adults.

Appearance: Small red bumps or pus bumps 2–5 mm, each at a hair follicle and often with a hair visible in the center, scattered across the buttocks and the backs of the thighs. Mildly painful or itchy. Each bump settles in 5–7 days, but new ones appear in their place.

Cause: Staphylococcus aureus living on the skin enters follicles that have been injured by friction, shaving, or moisture. People who carry the bacteria in the nose often have repeated episodes.

Severity/urgency: Low to moderate. Most cases can be managed with topical medicines, but if bumps merge into a large lump it becomes a boil.

When to see a doctor: No improvement after 2–3 weeks of the steps below, more than 3 episodes in 6 months, or fever and widening redness.

2. Pressure and Friction Acne (Acne mechanica)

Appearance: Blocked bumps and red bumps at the weight-bearing points when sitting, or along the lines of underwear and tight pants. Usually equal on both sides and clearly better on days off or when posture changes.

Cause: Pressure, heat, and sweat trapped under fabric cause the skin at the follicle openings to thicken and block. Seen in office workers, drivers, cyclists, and wheelchair users.

Severity/urgency: Low, but it will not clear while the cause remains.

When to see a doctor: Still marked after 6–8 weeks of adjusting how you sit and applying treatment, or deep inflamed nodules appear.

3. Keratosis Pilaris on the Buttocks

Appearance: Tiny rough bumps, 1–2 mm, skin-colored or slightly red, feeling like sandpaper, spread across the buttocks, backs of the thighs, and upper arms. Some have a dark ring around them. Rarely painful or itchy.

Cause: Keratin plugs the follicle openings. It is an inherited skin trait, common in teenagers and in people with dry skin or atopic dermatitis, and worse in cool weather or air-conditioned rooms.

Severity/urgency: Harmless and not contagious. No need to hurry.

When to see a doctor: You want treatment for rough skin or dark marks, or pus bumps start to mix in, which means folliculitis has developed on top. Read more at What Causes Keratosis Pilaris.

4. Fungal Acne on the Buttocks (Malassezia folliculitis)

Appearance: Red bumps or pus bumps of almost equal size, 1–2 mm, with clear itching, appearing together in clusters. Often also on the back, chest, and shoulders. No blackheads.

Cause: Malassezia yeast, which lives on everyone's skin, multiplies in the follicles when skin stays wet with sweat, after exercise, or after long courses of antibiotics that reduce the bacteria keeping the yeast in check.

Severity/urgency: Low, but it is often wrongly treated as acne or bacterial folliculitis, and antibiotics make it flare more.

When to see a doctor: No improvement with acne medicine or antibacterial products, or itching so severe it disturbs sleep. To tell fungal acne from heat rash, see What Causes Heat Rash.

5. Hot Tub Folliculitis

Appearance: Itchy red bumps and pus bumps appearing within 8–48 hours after a hot tub, jacuzzi, or an under-chlorinated pool. Worst where the swimsuit covers: the buttocks, hips, and trunk.

Cause: Pseudomonas aeruginosa in poorly maintained warm water. A wet swimsuit held against the skin for a long time helps the bacteria enter the follicles.

Severity/urgency: Low. Most cases clear on their own in 7–14 days.

When to see a doctor: Fever, swollen lymph nodes, breast or eye pain, or a weakened immune system.

6. Boils on the Buttocks (Furuncle / carbuncle)

Appearance: A red, hot, very painful lump of 1–3 cm that becomes soft when pus collects, possibly with a pus head in the center. When several boils join into one large lump with multiple heads it is called a carbuncle.

Cause: Staphylococcus aureus infection that goes deep into the hair root and the tissue beneath, following untreated folliculitis or squeezing acne.

Severity/urgency: Moderate to high, especially in people with diabetes.

When to see a doctor: A lump larger than 1 cm that is soft and full of pus, fever, redness spreading around the lump, or repeated boils. Do not squeeze it yourself. See more at What Causes Boils and Abscesses Under the Skin.

7. Hidradenitis Suppurativa of the Buttocks and Buttock Crease

Appearance: Deep painful lumps that keep coming back in the same place in the buttock crease, under the buttocks, in the groin, or around the anus. Some burst into draining tracts that leak for a long time, smell, and leave bands of scar that connect. Often also in the armpits or under the breasts.

Cause: Chronic blockage and inflammation of follicles in skin-fold areas. It is not an ordinary infection and is not caused by poor hygiene. It is linked to genetics, body weight, smoking, and hormones, and usually starts between ages 20 and 40.

Severity/urgency: Moderate to high. If left alone it spreads into tunnels under the skin and permanent scarring.

When to see a doctor: A painful lump in the same place more than 2 times in 6 months, or draining tracts. Read on at Hidradenitis Suppurativa.

8. Pilonidal Cyst and Lumps Under the Skin of the Buttocks (Pilonidal disease / epidermoid cyst)

Appearance: A pilonidal cyst is a swollen painful lump along the middle of the buttock crease above the tailbone. It may have a tiny hole of 1–2 mm with a hair sticking out, and when inflamed it drains pus. An epidermoid cyst under the skin is a round raised lump that moves when pressed, with a small opening in the center, growing slowly over months.

Cause: A pilonidal cyst forms when hairs pierce the skin in the buttock crease and create a cavity. It is seen in men aged 15–30 who are hairy and sit for long periods. An epidermoid cyst forms when skin lining ends up under the skin and builds up keratin.

Severity/urgency: A pilonidal cyst that is inflamed and full of pus is urgent. The pus needs to be drained, and surgery is often needed to keep it from coming back.

When to see a doctor: Every time there is a lump in the middle of the buttock crease. Acne medicine does not help this group. See more at Pilonidal Disease.

9. Acne-Like Bumps at the Anus, Itchy or Painful, Not Buttock Acne

A common related search is “acne-like bump at the anus, itchy.” Bumps at the edge of the anus are almost never acne, and need to be told apart from the following conditions.

Appearance: An itchy red rash around the anus with soggy or thickened skin is usually perianal dermatitis. Pink or skin-colored bumps with a rough, cauliflower-like surface are usually genital warts. Clusters of tiny clear blisters on a red, burning base are usually herpes. A red, hot, painful lump beside the anus that hurts when sitting or passing stool is usually a perianal abscess. A soft lump that protrudes during bowel movements with bright red blood is hemorrhoids.

Cause: Dermatitis is usually caused by moisture, vigorous wiping, soap, or scented tissue. Warts are caused by HPV and herpes by HSV, and both can be passed on through sex. A perianal abscess is caused by a blocked, infected gland inside the anus.

Severity/urgency: A perianal abscess is urgent and needs to be drained by a doctor within 24–48 hours, especially if there is fever.

When to see a doctor: Every time the bumps are at the anus. Do not apply steroid creams yourself for long, because they make warts and fungal infections worse. See more at Perianal Rash and What Causes Genital Warts.

Is Buttock Acne Different From Acne on the Hips?

Acne on the sides of the hips and waist usually has the same cause as buttock acne: folliculitis from waistbands and belts rubbing, as well as fungal acne spreading from the back. Bumps in the fold between the buttocks and thighs, or in the groin, point more toward hidradenitis suppurativa, intertrigo, and groin fungal infection. The location of the bumps tells you as much as how they look. If the rash in a fold is a red patch with a clear edge and itches, see What Causes Ringworm of the Groin and Intertrigo.

How Does a Doctor Diagnose Buttock Acne?

Most of the time a dermatologist can diagnose it by looking at the bumps and taking a history, which usually covers hours spent sitting, type of clothing, hair removal, exercise, current medicines, and how often it comes back. Additional tests that may be used:

Skin scraping for fungus (KOH): separates fungal acne from bacterial folliculitis within minutes.
Pus culture: used when boils keep coming back or treatment does not work, to look for resistant bacteria such as MRSA.
Blood sugar test: in people with frequent boils, because undiagnosed diabetes is a possible cause.
Testing for sexually transmitted infections: when the bumps are around the anus or groin.
Skin biopsy: only in cases that are unclear or do not respond to treatment.

Medicines for Buttock Acne: Which One, and for How Long?

The medicines below are common generic drugs dermatologists often choose. Strength, duration, and combinations depend on the type of bump and its severity, which a doctor assesses and prescribes.

Benzoyl Peroxide Wash

Used for bacterial folliculitis and friction acne. The form that suits the buttocks is a wash gel or foam at 4–10% (5% is common). Lather onto wet skin, leave on for 2–5 minutes, then rinse off, once a day. Results usually show in 4–6 weeks. Good to know: benzoyl peroxide bleaches fabric, so towels and dark underwear will be stained. Use white ones. It may also cause dryness and stinging in the first week.

Clindamycin 1%

A topical antibiotic in lotion or gel form, applied twice a day on inflamed bumps for 2–4 weeks. Doctors often have it used together with benzoyl peroxide to reduce resistance. A topical antibiotic should not be used alone, continuously, for months.

Mupirocin 2% or Fusidic Acid 2%

Antibiotic cream or ointment for a few scattered bumps, applied 3 times a day for 5–10 days. Not suitable for large areas or longer use.

Salicylic Acid and Urea

For keratosis pilaris and blocked bumps from pressure, use urea cream 10–20% or lactic acid 12% once or twice a day after bathing, or salicylic acid 2% soap or lotion. Results show in 4–8 weeks, and it needs to be applied continuously as long-term care, because keratosis pilaris can return once you stop.

Adapalene 0.1%

A retinoid, applied in a thin layer at night. It helps blocked bumps from friction and keratosis pilaris that has not responded to the medicines above. It may irritate in the first 2 weeks, so start every other night. Do not use during pregnancy.

Ketoconazole 2% Shampoo

For fungal acne, use the shampoo in place of soap on the buttocks and back. Lather on wet skin, leave on for 5 minutes, then rinse off, every day for 2–4 weeks, then 1–2 times a week to prevent it coming back. A topical antifungal cream may be added.

Oral Medicines for Buttock Acne: When Are They Needed?

Oral medicines are not the first step. A doctor considers them when bumps are widespread, deep, or boils, or when topical treatment has not worked.

Widespread folliculitis or boils: antibiotics such as cephalexin 500 mg four times a day, or dicloxacillin, for 7–10 days. For chronic acne-like inflamed bumps, doxycycline 100 mg once or twice a day for 6–12 weeks may be used. This medicine makes skin sensitive to sun, and must be taken with plenty of water and not just before lying down.
Widespread fungal acne: a short course of oral antifungals such as itraconazole or fluconazole. The doctor must check your other medicines, because these interact with many drugs.
Recurrent boils from carrying the bacteria: the doctor may have mupirocin applied inside the nostrils twice a day for 5 days, together with periodic washing with 4% chlorhexidine, to reduce bacteria on the body.
Hidradenitis suppurativa: topical clindamycin, oral doxycycline for 12 weeks, and in moderate to severe cases the doctor may consider a biologic such as adalimumab together with targeted surgery.

How Is a Buttock Boil Treated? Does It Need Lancing?

For a small boil that is still firm, apply a warm compress for 10–15 minutes, 3–4 times a day, so the pus collects and drains on its own. When the lump is soft with clear pus, a doctor will lance and drain it under local anesthetic, which is the main treatment for boils. Oral antibiotics are used when redness spreads around the lump, there is fever, there are several lumps, or the person has diabetes or a weakened immune system. Squeezing a boil yourself pushes the bacteria deeper and can lead to spreading soft-tissue infection (cellulitis).

Self-Care for Buttock Acne

Get up and change position every 45–60 minutes: reduces constant pressure on the skin. If you must sit for long periods, use a breathable cushion.
Shower right after sweating: after exercise or walking in the sun. Do not stay in sweat-soaked clothes or a wet swimsuit.
Choose cotton and loose pants: wear cotton underwear and change it daily. Wear workout pants only while exercising.
Pat dry: do not rub hard, and do not use scrubbing pads or coarse scrubs, because they injure the follicles.
Shave or wax less: if you need to remove hair, trim it short instead of shaving close, or ask a doctor about methods that cause less injury.
Do not squeeze or pick: lowers the chance of boils and of dark marks on the buttocks.
Apply fragrance-free moisturizer: important for people with keratosis pilaris or dry skin.

Why Won't My Buttock Acne Go Away?

Wrong type of medicine: using facial spot treatment on fungal acne, or antibiotics on keratosis pilaris, which do not match the cause.
The cause is still there: still sitting for long hours every day or still wearing tight, sweaty pants.
Not using the medicine long enough: most medicines need at least 4–8 weeks before you can judge whether they work.
Carrying staph bacteria: boils or folliculitis keep coming back until the bacteria in the nostrils and on the skin are reduced.
Applying steroid creams yourself: makes fungal acne, folliculitis, and groin fungal infection spread more.
It was never acne: for example hidradenitis suppurativa or a pilonidal cyst, which need a different kind of treatment.

Dark Buttocks From Acne: Will They Fade, and How Are They Treated?

Dark buttocks after acne are mostly post-inflammatory hyperpigmentation, which is common in brown skin tones like those of Thai people. These marks fade gradually on their own in 3–12 months if no new inflamed bumps keep coming. So the first step is to stop new bumps.

Topical medicines for dark marks that a doctor may use: azelaic acid 15–20%, niacinamide 4–5%, or hydroquinone 2–4%, which must be used under a doctor's supervision and should not be used continuously for more than 3 months.
Stop scrubbing: scrubbing or rubbing hard inflames the skin and makes it darker.
Tell it apart from friction darkening: darkness across the whole sitting area without ever having had bumps is usually from chronic pressure and friction. Thick, velvety dark skin in the groin or neck points toward insulin resistance. See more at Treating Dark Groin and Dark Thighs and Post-Inflammatory Hyperpigmentation (PIH).

Warning Signs: See a Doctor Right Away

Fever, chills, or redness around a bump that widens within 24 hours, which may be cellulitis
A red, hot, painful lump larger than 1 cm that is soft with pus or has several heads
A painful lump at the edge of the anus, with pain when sitting or passing stool
A swollen painful lump in the middle of the buttock crease above the tailbone
Chronically draining tracts or connected scars in the buttock crease and groin
Having diabetes, being on dialysis, taking immunosuppressants, or receiving chemotherapy, and developing a boil or pus bumps
More than 3 boils in 6 months

Common Myths About Buttock Acne

“Buttock acne is from being unclean”: Not entirely true. Scrubbing hard several times a day actually makes the follicles more inflamed.
“I can use facial acne spot treatment too”: Only certain kinds work. Spot treatments do not help keratosis pilaris, fungal acne, or pilonidal cysts. For help choosing ingredients, see Which Acne Spot Treatments Really Work.
“Squeezing the pus out makes it heal faster”: Squeezing it yourself causes deeper boils and leaves dark marks that last longer.
“Scrubbing often makes buttocks smooth”: Coarse scrubbing injures the skin, causing folliculitis and dark buttocks.
“A bump at the anus is ordinary acne”: Bumps there must always be told apart from warts, herpes, dermatitis, and perianal abscess.

In Brief

Most buttock acne is folliculitis, not true acne, caused by prolonged sitting, sweat, and friction.
Tiny rough painless bumps are keratosis pilaris, equal-sized very itchy bumps are fungal acne, and a red hot lump over 1 cm is a boil.
Commonly used medicines are benzoyl peroxide wash 4–10% left on for 2–5 minutes and clindamycin 1% twice a day, while fungal acne uses ketoconazole 2% left on for 5 minutes.
Lumps that keep coming back in the buttock crease, groin, or around the anus are not acne and need a doctor's examination.
Dark buttocks from acne can fade in 3–12 months once new bumps have stopped.
If there is no improvement after 2–3 weeks of treatment matched to the type, or if there is fever, see a dermatologist.

Frequently Asked Questions About Buttock Acne

What causes buttock acne?

Most buttock acne is caused by folliculitis, a Staphylococcus bacterial infection at the follicle opening, together with triggers such as prolonged sitting on the area, sweat and moisture, tight pants, and shaving or waxing. Other causes include keratosis pilaris, which is tiny rough painless bumps; fungal acne, which is equal-sized bumps that itch a lot; boils, which are red, hot, painful lumps; and conditions specific to the area such as hidradenitis suppurativa and pilonidal cysts. Treatment therefore differs by type of bump, and the type should be identified before choosing a medicine.

Does sitting a long time really cause buttock acne?

Yes. Sitting continuously for many hours presses, heats, and traps sweat on the skin of the buttocks, so follicle openings swell and block easily, causing pressure acne and folliculitis. It is common in office workers, drivers, and students. To reduce it, get up and change position every 45–60 minutes, use a breathable cushion, wear loose cotton pants, and shower after sweating, together with a benzoyl peroxide wash as a doctor advises. If there is no improvement after 6–8 weeks of adjusting, a doctor should check whether it is another type.

What causes an itchy acne-like bump at the anus?

An itchy bump at the edge of the anus is almost never acne. A common cause is perianal dermatitis from moisture, vigorous wiping, or scented soap and tissue, which usually appears as an itchy red rash. Rough skin-colored bumps are usually genital warts, and clusters of clear burning blisters are usually herpes, both of which can be passed on through sex. A red, hot, painful lump that hurts when sitting or passing stool may be a perianal abscess, which a doctor must drain. Do not apply steroid creams yourself for long. See a doctor every time.

Is acne on the hips different from buttock acne?

Mostly it is the same condition. Acne on the sides of the hips and waist is usually folliculitis from waistbands or belts rubbing, or fungal acne spreading from the back and waist. Care is therefore similar: reduce friction, shower after sweating, and use medicine matched to the type of bump. Be careful with bumps in the fold between the buttocks and thighs or in the groin, because they may be hidradenitis suppurativa, intertrigo, or groin fungal infection, which use different medicines from acne. If you are unsure, have a dermatologist look at the location and the appearance of the bumps.

What should I apply for buttock acne?

It depends on the type of bump. Bacterial folliculitis usually uses benzoyl peroxide wash gel 4–10% left on for 2–5 minutes and then rinsed off, once a day, together with clindamycin 1% twice a day for 2–4 weeks. Keratosis pilaris uses urea cream 10–20% or salicylic acid. Fungal acne uses ketoconazole 2% shampoo lathered on and left for 5 minutes. For just a few bumps, mupirocin or fusidic acid 2% may be applied 3 times a day for 5–10 days. The choice of medicine and its duration should be assessed by a doctor.

Will dark buttocks from acne go away?

They can. Dark buttocks after acne are mostly post-inflammatory hyperpigmentation, which fades gradually on its own in 3–12 months if no new bumps appear. The most important thing is therefore to get the bumps to stop first, and to avoid scrubbing or rubbing hard. A doctor may use topical medicines for dark marks such as azelaic acid, niacinamide, or hydroquinone for a short period under supervision. If the buttocks are dark across the whole sitting area without ever having had acne, it is usually chronic friction, which also needs a change in sitting and clothing.

If bumps also appear on the back or neck, see What Causes Back Acne and What Causes Neck Acne. For details on folliculitis, read What Causes Folliculitis, and for other skin disease articles, see All Skin Disease Articles.

Written by Dr. Patara Voravutinon, Dermatologist · Last reviewed October 28, 2026

The information in this article is general knowledge and is not a diagnosis or an individual prescription. Many kinds of buttock bumps look alike and need to be examined by a doctor. The choice of medicine, dose, and length of treatment is the doctor's decision. Results vary from person to person.