Bumps on Your Bottom: Folliculitis or Keratosis Pilaris?

“Butt acne” is the popular name, and it sends people straight to the acne aisle. Two other conditions are common on the buttocks, and they need different care.

The two usual suspects

	Folliculitis	Keratosis pilaris (KP)
What it is	An inflamed hair follicle: a tender red spot, often with a pus-filled tip1	Plugs of skin protein in the follicles, the “chicken skin” bumps2
Feel	Tender or sore1	Rough and dry, sometimes itchy2
Color	Red, with pustules1	Skin-colored, red or brown2
Where else	Chest, back, arms, legs1	Mostly the upper arms and thighs2
On the buttocks	“Quite common” in men and women1	30% of people in one survey3

Folliculitis on the buttocks

It comes in two speeds. Acute buttock folliculitis is usually bacterial, like boils: red, painful bumps and pustules that clear with antibiotics.¹ Chronic folliculitis causes few symptoms but can last a long time.¹

Common triggers:

• Hair regrowing after shaving, waxing or plucking.¹
• Thick ointments and moisturizers, which can block follicles; an oil-free moisturizer is less likely to.¹

For persistent cases on hairy skin, permanent hair reduction with laser or IPL may be the best option, since regrowth can make it worse.¹

Keratosis pilaris on the buttocks

In a survey of 49 people with KP, 30% had it on the buttocks, and 80% noticed it changed with the seasons, often worse in winter.³ Moisturizers with urea, salicylic acid or lactic acid help loosen the plugs.² See the harsh-scrub myth.

Sorting your own bumps

• Rough, painless, there for years, worse in winter: leans KP.²³
• Sore, red, pus-filled, came on fast: leans acute folliculitis; see a clinician.¹
• Started after you began shaving or waxing there: leans folliculitis from regrowth.¹
• Same-sized, itchy bumps on the back and chest too: see fungal folliculitis.

On brown and black skin, inflamed bumps may look brown or purple rather than red.

Try: “I’ve had rough bumps on my bottom for years that get worse every winter, and lately a few are sore. Is this KP, folliculitis, or both?”

Skin, Head to Toe covers this in Chapter 6, “Bumps, Backs and Bottoms,” in a section called “The Bottom Line on Butt Bumps.” Its Skin Sort puts painful, pus-filled bumps in the Clue box and rough, painless KP in Normal or Try. See the book.