Keratosis pilaris vs acne: how to tell them apart

Many people treat small bumps on the upper arms or thighs with acne products. Often the bumps are keratosis pilaris, a common skin condition that the American Academy of Dermatology (AAD) says people often mistake for small pimples. Some people call it "chicken skin", because the AAD says the bumps can look like goosebumps or the skin of a plucked chicken. This guide puts the two side by side, shows which acne medicines appear in keratosis pilaris care, and says what the AAD recommends for it. It is part of Skinli's guide to the types of acne.

If your bumps are on the arms and legs and you also want to rule out folliculitis and hidradenitis suppurativa, read acne on arms and thighs. This page stays on one question: is it keratosis pilaris or acne, and what changes once you know?

Skinli is an education site and is not a doctor. A dermatologist, a doctor who treats skin, can tell the two apart by looking at your skin.

The two side by side

Sign	Keratosis pilaris	Acne
How it feels	Rough and dry, like sandpaper	Oily or greasy skin around the spots
Where it shows up	Upper arms, front of the thighs, buttocks. Cheeks in children	Face, chest and back
What the bumps are	Plugs of dead skin cells in the hair follicles	Follicles blocked with oil and dead skin, often with bacteria
Types of spots	Tiny bumps	A mix: blackheads, whiteheads, red bumps, pus bumps, sometimes deep lumps
Pus	Not part of the condition	Common in pustules
Season	Often worse in winter and in dry air	The sources used here give no seasonal pattern
Family	Thought to run in families	Many causes, including hormone changes

The AAD pages on keratosis pilaris and the NHS pages on keratosis pilaris and acne are the sources for each row. The details follow.

What each one is

The NHS says keratosis pilaris happens when your hair follicles become blocked with a build-up of keratin. Keratin is a protein found in skin, hair and nails. A hair follicle is the small opening in the skin that each hair grows from. The AAD describes the result as "plugs of dead skin cells". Nobody knows exactly why the keratin builds up, the NHS says, but the condition is thought to run in families. It is not infectious.

Acne starts in the same small openings, with a different mix inside. The NHS says acne can happen when hair follicles "become blocked with excess oil and dead skin cells", and that bacteria can grow in those blocked follicles and cause swelling and pus. The NHS lists hormone changes (puberty, periods, pregnancy, menopause), some medicines, and greasy skin or hair products among the causes.

So both conditions involve a plugged follicle. Oil and bacteria are part of acne. The keratosis pilaris pages from the AAD and the NHS describe a dry plug of keratin, and they name no bacteria in its cause. That difference explains most of what follows.

Five ways to tell them apart

1. Touch the skin. The AAD's page on skin conditions that look like acne gives this as the first clue: "Unlike pimples, these bumps feel rough and usually appear on dry skin." Acne-prone skin tends to feel oily, and the NHS lists oily or greasy skin as a symptom of acne.

2. Look at where the bumps are. The AAD says keratosis pilaris bumps appear most often on the upper arms and the front of the thighs. In teens and adults it adds the buttocks. The NHS says acne usually affects the face, chest and back. Keratosis pilaris never appears on the palms or the soles, the AAD says, and some people have so many bumps that they spread to the forearms and lower legs.

3. Check the kinds of spots. Acne comes in several forms at once. The NHS lists whiteheads, blackheads, papules (raised pink, red, brown or purple bumps), pustules (raised bumps filled with pus), and nodules and cysts (larger lumps under the skin that can hurt). Keratosis pilaris makes tiny bumps. The AAD says they can be skin colored, white, red, pinkish purple on fair skin, or brownish black on dark skin.

4. Think about the season. The AAD says many people see the bumps clear in summer and return in winter. People who live in a dry climate or swim often in a pool may have them all year.

5. Look at your family. The AAD says you may notice that family members have the same bumps. The NHS says that if your parents have it, you may get it too.

One point can mislead you. Red keratosis pilaris bumps, or many bumps close together, can look like a rash of pimples. The AAD says some people have only a few bumps, while others have noticeable bumps that look like pimples or a rash. So use all five checks together, and ask a dermatologist when the answer is still unclear.

Keratosis pilaris on the face

Searches for keratosis pilaris on the face and cheeks are common. The AAD says children may have the bumps on their cheeks. For teens and adults, it lists the upper arms, the front of the thighs and the buttocks.

On an adult face, bumps with blackheads, whiteheads or pus fit acne better. Redness that comes and goes, with stinging or burning, fits the AAD's description of rosacea, which Skinli compares with acne in rosacea vs acne. Small white bumps on the face have their own look-alikes, covered in white bumps on the face that are not milia. A dermatologist can confirm which one you have.

Acne medicines and keratosis pilaris

Acne products aim at acne's causes. The AAD recommends a benzoyl peroxide wash for acne because it "can help get rid of the excess P. acnes bacteria on your skin". Keratosis pilaris has no bacteria in its cause in the AAD and NHS pages, and benzoyl peroxide is absent from every AAD list of ingredients for keratosis pilaris. More on the wash itself is in Skinli's benzoyl peroxide guide.

Here are the acne medicines people ask about most, and what the sources say for keratosis pilaris:

Medicine	What the source says about acne	Keratosis pilaris
Benzoyl peroxide	AAD: a wash helps remove excess acne bacteria	Not on the AAD's keratosis pilaris lists
Adapalene (a retinoid)	AAD: dermatologists recommend a retinoid to unclog pores	On the AAD's keratosis pilaris lists
Azelaic acid	FDA label (Azelex): for mild to moderate inflammatory acne (red, swollen spots)	Not on the AAD's lists. The label lists reddening, described as signs of keratosis pilaris, among rare reported side effects
Isotretinoin (Accutane)	FDA label (Amnesteem): for severe nodular acne after other treatment fails	Not on the label and not on the AAD's treatment page

Adapalene is the one overlap. The AAD lists retinoids, including adapalene, retinol, tazarotene and tretinoin, as products that remove the dead skin cells that plug the follicles in keratosis pilaris. It is also one of the two treatment gels in Skinli's acne plan, at 0.1 percent, together with benzoyl peroxide at 2.5 percent. Skinli's plan uses them on facial acne, and skin needs 8 to 12 weeks to show change. Using adapalene on keratosis pilaris on the arms is a separate decision to make with a dermatologist or pharmacist.

Azelaic acid comes up often in searches about keratosis pilaris. The AAD's keratosis pilaris pages do not include it in their ingredient lists, and the drug label mentions keratosis pilaris only among rare side effects. For what azelaic acid does on acne, see azelaic acid for acne.

What the AAD says helps keratosis pilaris

The AAD says you do not have to treat keratosis pilaris. Treatment helps if the itch, the dryness or the look of the bumps bothers you. The care it describes centers on dry skin.

• Moisturize often. The AAD says most creams used for keratosis pilaris contain urea or lactic acid. Put the cream on damp skin within 5 minutes of a bath or shower, and at least 2 or 3 times a day. The AAD prefers a thick, oil-free cream or an ointment for this.
• Remove dead skin gently. A loofah or washcloth is enough, the AAD says. It warns that scrubbing irritates the skin and makes keratosis pilaris worse. The NHS also says not to use harsh scrubs.
• Add a keratolytic if needed. A keratolytic is a product that loosens dead skin cells. The AAD lists alpha hydroxy acids such as glycolic and lactic acid, retinoids, salicylic acid and urea. Use it exactly as the directions say, and stop for a few days if the skin gets dry or irritated.
• Keep baths short and warm. The AAD says 20 minutes or less, once a day, with warm water. The NHS says to avoid hot baths and showers.
• Use a mild cleanser. The AAD says bar soap can dry the skin. The NHS says to avoid perfumed soaps.
• Leave the bumps alone. The NHS says not to scratch, pick or rub the skin.

The AAD adds that shaving or waxing can cause more bumps, that self-tanner makes the bumps more obvious, and that a humidifier helps when the air is dry. For the full step-by-step home plan, see acne on arms and thighs.

The AAD says treatment cannot cure keratosis pilaris, so people need a maintenance plan to keep the bumps under control, which may mean using the product twice a week instead of every day. It also says that for many people, keratosis pilaris goes away over many years, even without treatment.

If you have both

Acne on the face and keratosis pilaris on the arms can happen at the same time. In that case, treat them as two separate problems with two sets of products. Keep the acne routine on the areas with acne. Care for the arms and thighs with the moisturizer and gentle washing above, because the AAD says keratosis pilaris often flares when skin gets dry.

Skinli's free acne plan reads a photo of your face and builds an acne routine from it. It is made for facial acne and cannot assess bumps on the arms or legs.

When to see a dermatologist

The AAD says a dermatologist diagnoses keratosis pilaris by looking closely at the skin. See one if:

• You have followed a keratosis pilaris plan for 4 to 6 weeks and see no change. The AAD says to tell your dermatologist then, and that some people need to try a few treatments before one works.
• The bumps are painful, leak pus or keep coming back in the same spot. Those signs point away from keratosis pilaris.
• Your skin becomes itchy or inflamed. The NHS says to speak to a pharmacist in that case, and a pharmacist can tell you if you need a doctor.
• You are not sure whether a child's rash is keratosis pilaris.

A dermatologist can also offer treatments you cannot buy in a shop. The AAD lists prescription creams that remove dead skin, a corticosteroid cream to soften the bumps and reduce redness, and laser or light treatment when moisturizer and medicine fail. The NHS says steroid creams and laser treatment for keratosis pilaris are not usually available on the NHS, because they have not been proven to work and can be expensive to pay for privately.