Butt acne: what causes it and what helps

Bumps on the buttocks are common, and they come from several conditions. Three are usually harmless: folliculitis, keratosis pilaris and true acne. A fourth, hidradenitis suppurativa, needs a doctor. Each one has its own fix. This guide explains how to tell them apart, what helps, and when to see a doctor. It is part of Skinli's guide to the types of acne.

Four causes of bumps on the buttocks

Condition	What it looks like	What helps
Folliculitis	Looks like a sudden acne breakout, with a red ring around each spot; may itch or hurt	Stopping the cause, warm compresses, sometimes an antibiotic from a doctor
Keratosis pilaris	Small, rough bumps, skin-colored or red, often worse in winter	Moisturizer, mild soap, no harsh scrubs
Acne	Blackheads, whiteheads, red bumps, pus-filled bumps	Acne products, loose clothes, time
Hidradenitis suppurativa	Deep, painful lumps where skin touches skin, often coming back in the same spot	A dermatologist, early

The sources for each row are the American Academy of Dermatology (AAD) and the NHS, as set out below.

Folliculitis: infected hair follicles

Folliculitis is an infection of the hair follicles, the small tubes in the skin that each hold a hair. The AAD calls it a common skin infection that usually looks like a sudden acne breakout. Each spot may have a red ring around it, which is a sign of the infection. It may itch, hurt, or cause no feeling at all.

It starts when hair follicles are damaged and germs get in. The AAD says a common source is Staph aureus, a bacterium found on the skin. It lists these ways to damage the follicles:

• Touching or rubbing the skin often
• Wearing tight clothing
• Skin rubbing against skin
• Shaving, plucking or waxing

Heat and damp make it worse. The AAD says follicles are easier to damage when skin is hot and damp, such as tight clothing rubbing during a bike ride on a hot day. The AAD's page on bumps in children says folliculitis bumps tend to form on skin covered by clothing, such as the buttocks or thighs, and that in children the cause is often tight clothing.

Hot tub folliculitis

The AAD describes a version that follows a hot tub or whirlpool that is not well maintained. The bumps tend to appear on skin that was covered by a swimsuit, 12 to 48 hours after using the hot tub. It is common enough to have its own name: hot tub folliculitis.

What helps folliculitis

The AAD says the bumps tend to go away on their own if you have a healthy immune system and stop doing what caused them. To heal faster and feel better, it recommends a warm compress:

1. Apply a warm compress at least 3 to 4 times a day.
2. Leave it on for 15 to 20 minutes each time.
3. You can use it more often if it makes you more comfortable.

If shaving, plucking or waxing caused it, the AAD suggests stopping for 30 days. It says some people need medicine, such as an antibiotic, and that a dermatologist can confirm whether the bumps are folliculitis, since infected follicles can look like acne.

Keratosis pilaris: rough, harmless bumps

The NHS describes keratosis pilaris as a common, harmless condition that causes patches of small bumps, usually on the arms, thighs or bottom. The bumps are usually skin-colored, and can be red on white skin or darker on brown or black skin. The skin can feel rough and itchy, and is often better in summer and worse in winter.

The AAD says the bumps are plugs of dead skin cells, and that people often mistake them for small pimples. The NHS says they happen when hair follicles are blocked with keratin, a substance found in skin, hair and nails, and that the condition tends to run in families. It is not infectious.

The NHS advice:

• Moisturize the skin, and ask a pharmacist what suits you.
• Use mild, unperfumed soaps.
• Have cool or lukewarm showers.
• Avoid harsh scrubs, which can make it worse, and do not scratch or pick.

True acne on the buttocks

Ordinary acne can appear on the buttocks too. MedlinePlus says acne commonly appears on the face and shoulders and may also occur on the trunk, arms, legs and buttocks. The AAD says severe acne sometimes develops on the buttocks.

Acne there follows the same rules as anywhere else. The AAD recommends benzoyl peroxide or salicylic acid products for red and pus-filled bumps, and a retinoid for blackheads and whiteheads. It says to give a product 6 to 8 weeks. Benzoyl peroxide bleaches fabric, so the AAD's back acne advice to rinse it off after a few minutes also protects underwear and sheets. The back acne and chest acne guides cover body acne treatment step by step.

Hidradenitis suppurativa: the one that needs a doctor early

Hidradenitis suppurativa (HS) is a long-term skin condition that can look like acne or boils at first. The AAD says its first sign is often a painful spot that looks like a deep pimple, acne cyst or boil, usually in the armpit or groin. Some people get it on the buttocks or inner thigh.

The AAD's stubborn acne page gives the main clue: pimple-like bumps or deep, acne-like cysts in places where skin touches skin, such as the underarm, groin, buttocks or upper thighs. The NHS says the lumps can leak pus, form channels under the skin, and leave scars. It also says HS could be mistaken for acne or ingrown hairs, and that it is not infectious and not linked to poor hygiene.

The AAD says the breakouts often clear for a while and then come back in the same area, sometimes in exactly the same spot. It says treatment can stop HS from getting worse, which is why early diagnosis matters. The NHS says the same: it is important to recognise the condition early.

Boils

A boil is a hard, painful lump that fills with pus, the NHS says. Most go away on their own. The NHS suggests holding a clean cloth soaked in warm water against the boil for 10 minutes, 4 times a day, and says never to pick, squeeze or pierce it. See a GP if a boil lasts 2 weeks or you keep getting them.

How to tell them apart at home

A few questions point toward one cause or another. A doctor's exam confirms the cause. These questions help you describe the bumps at the appointment:

• Did the bumps appear suddenly, after a hot tub, a long ride, a new pair of tight trousers, or shaving? The AAD links all of these to folliculitis.
• Do the bumps feel rough, like sandpaper, and appear on the thighs and upper arms too? The AAD and the NHS describe keratosis pilaris this way.
• Do you also have blackheads and whiteheads, and acne on your back or chest? That pattern fits ordinary acne.
• Are there deep, sore lumps in the fold of the buttocks, the groin or the armpits, which come back in the same place? The AAD and the NHS describe hidradenitis suppurativa this way, and it needs a doctor.

Everyday habits that help

The AAD's advice for preventing folliculitis fits most butt bumps:

• Wear loose clothing when it is hot and humid.
• Change out of tight workout clothes and shower right after exercise.
• Wash your swimsuit or wetsuit after each use and let it dry fully.
• Use hot tubs that are well maintained.
• Shave with care, or take a break from shaving.

Two more come from the AAD's acne tips: keep your hands off the bumps, since picking makes acne slower to clear and raises the risk of scars and dark spots, and choose body products labeled "non-comedogenic" or "won't clog pores".

When to see a doctor

See a doctor or dermatologist if:

• The lumps are deep and painful, or keep returning in the same place. The AAD says this pattern in skin folds can be HS.
• A boil lasts 2 weeks, or you keep getting boils, as the NHS advises.
• A lump comes with hot, swollen skin, or you feel hot, cold or shivery. The NHS says to ask for an urgent appointment in that case.
• You have pimple-like bumps in unusual places, such as the armpit, groin or thighs. The AAD lists this as a reason to see a dermatologist.
• Warm compresses and a break from the cause have not helped.

A dermatologist can tell folliculitis, keratosis pilaris, acne and HS apart by looking, and can test the skin when needed. Some itchy bumps on the body are fungal acne, which needs antifungal treatment. For daily care of the rest of your skin, see the complete acne skincare routine and how to patch test a new skincare product before trying anything new on sensitive skin.