Keratosis Pilaris: Causes and How Well Treatment Works, by a Dermatologist
Keratosis pilaris is a condition in which keratin blocks the opening of hair follicles, leaving small firm bumps about 1–2 millimetres wide, packed closely together, with a rough texture like sandpaper or goose bumps. It is most common on the outer upper arms, thighs, buttocks and cheeks. The condition itself is not contagious, not dangerous, and is not caused by poor washing.
The straight answer to the question people search for most: true keratosis pilaris can be treated so the skin becomes smoother, but it does not go away permanently, because it is an inherited trait of the hair follicles. Using a keratin-dissolving medication correctly and consistently for 4–8 weeks makes the skin clearly smoother and less rough, but if you stop, the bumps usually return within 1–3 months. The good news is that keratosis pilaris tends to improve on its own with age, and about half of patients see a marked reduction after age 30.
This article is written by a dermatologist. It separates what Thai people loosely call “khon khut” into what are actually two different conditions, explains how each body area looks one by one, names the actual medications with their concentrations and how long they need to be used, and says plainly what procedures can and cannot do.
What is keratosis pilaris, and what happens in the skin
In normal skin, outer skin cells shed from the follicle opening in a regular cycle. In people with keratosis pilaris, keratin, the structural protein of skin cells, builds up and plugs the follicle opening into a hard plug. Two things follow: the skin becomes raised and rough with small bumps, and the hair inside is trapped and cannot grow out, so it curls up under the plug and shows as a dark dot or a coiled hair inside the bump.
Modern microscope studies suggest the root cause may not start with keratin, but with an abnormality of the hair shaft and the sheath around the hair root, which makes the hair grow in the wrong direction and then disturbs cell shedding at the follicle opening. This explains why scrubbing alone never truly cures it.
Numbers worth knowing
It affects about 50–80% of adolescents and about 40% of adults.
It is inherited in an autosomal dominant pattern, with a family history in about 30–50%.
It usually begins at age 2–10 years and is most noticeable in adolescence.
It often gets worse in winter and in air-conditioned rooms because the skin is drier than usual.
The most common misunderstanding: in Thai, “khon khut” means two different conditions
The problem seen most often in the clinic is patients buying the wrong type of product, because the Thai word “khon khut” is used for both conditions together, even though their mechanism, location and treatment are completely different. Telling them apart is the first step to successful treatment.
Cause — True keratosis pilaris comes from inherited keratin plugging of the follicle opening. Ingrown hairs come from hair tips cut at a sharp angle that pierce back into the skin after shaving, waxing or plucking.
Location — True keratosis pilaris appears on the outer upper arms, thighs, buttocks and cheeks. Ingrown hairs appear in the armpits, groin, shins, beard area and bikini line.
Appearance — True keratosis pilaris is small, firm, even bumps, rough across the whole patch, and painless. Ingrown hairs are red bumps or pustules scattered unevenly, and can be tender.
Visible hair — In true keratosis pilaris you see a coiled hair under the keratin plug. In ingrown hairs you clearly see a curved hair burrowing back into the skin.
Response to keratin-dissolving medication — True keratosis pilaris responds well. Ingrown hairs respond only partly and need the hair removal method fixed at the same time.
Chance of a permanent cure — True keratosis pilaris can be controlled but not cured. Ingrown hairs can clear if you stop the hair removal method that causes them.
A 10-second way to tell at home: Run your hand over the outer upper arms on both sides. If both sides are equally rough and it has been there since childhood, it is true keratosis pilaris. If the bumps appear only where you recently shaved or waxed, and appear after every hair removal, it is ingrown hairs.
True keratosis pilaris — getting to know the condition fully
Appearance Firm bumps 1–2 millimetres wide, skin-coloured or white, arranged in an even patch, with skin as rough as goose bumps and no pain. It may itch slightly when the skin is dry.
Cause Keratin plugging the follicle opening together with an abnormality of the hair shaft. Contributing factors are genetics, dry skin, cold weather and existing atopic dermatitis.
Severity/urgency Not urgent, not contagious, and does not become cancer. The main impact is on confidence and how the skin feels.
When to see a doctor If there is no improvement after using a keratin-dissolving medication continuously for 8 weeks, if there are red inflamed bumps or pus, if it appears on a child's face with pitting or thinning hair, or if the dark marks it leaves bother you.
Ingrown hairs from shaving and waxing (Pseudofolliculitis)
Appearance Raised red bumps or small pustules scattered unevenly, some with a curved hair visible burrowing under the skin, tender to press. They may leave dark spots.
Cause Shaving too close, shaving against the grain, or repeated waxing or plucking leaves hair tips cut to a sharp point that pierce back into the follicle wall. It is more common in people with naturally coarse, curly hair.
Severity/urgency Not dangerous, but if it becomes inflamed repeatedly in the same place it can lead to permanent dark marks and raised scars, especially in the groin and beard area.
When to see a doctor When the bumps become more swollen, red, warm and painful within 2–3 days, pus grows larger, you have a fever, or it recurs every time you remove hair and self-care cannot keep up. In that last case, consider changing to a permanent hair removal method.
Inflamed keratosis pilaris, red type (Keratosis pilaris rubra)
Appearance The same keratin bumps, but with diffuse redness around the bumps, most visible on the upper arms, thighs and cheeks. Some people are so red that it looks like an allergic rash over the whole area, yet it still feels rough and granular to the touch.
Cause Inflammation around the follicle together with dilated capillaries. It is often made worse by hard scrubbing, using acids that are too strong, degreasing soaps and hot water.
Severity/urgency Not dangerous, but harder to treat than the ordinary type, and strong exfoliation must be avoided because it makes the redness worse.
When to see a doctor When the redness is so marked that it cannot be told apart from atopic dermatitis or rosacea, because these use different classes of medication. A wrong diagnosis followed by continued acid creams makes things worse quickly.
Keratosis pilaris on the upper arms — the most common location
Appearance A rough, bumpy rash on the outer upper arms on both sides, clearly symmetrical. This is the classic location for true keratosis pilaris and hardly needs further differential diagnosis.
Cause Almost always true keratosis pilaris. The skin here dries easily and is often neglected when applying cream.
Severity/urgency Low. It responds to treatment best of all locations, because the skin is thick and tolerates higher concentrations of keratin-dissolving medication.
When to see a doctor If urea or lactic acid combined with a moisturiser twice a day for 8 weeks still gives no softening at all, a doctor should assess whether you need to move up to the retinoid group.
Keratosis pilaris on the legs and calves — the location most mixed up with shaving problems
Appearance On the outer and back of the thighs it is usually true keratosis pilaris, while on the shins and calves it is usually ingrown hairs from shaving mixed with fish-scale-like dry skin. Some people have both on the same leg.
Cause True keratosis pilaris plus regular leg shaving. Leg skin is drier than other areas because it has fewer oil glands.
Severity/urgency Low, but this is the location that leaves dark marks most easily in Thai skin, because it is shaved, scrubbed and picked repeatedly.
When to see a doctor When dark spots on the legs keep increasing even though the bumps have flattened. That is post-inflammatory dark marking, which needs a different approach from the keratosis pilaris itself.
Keratosis pilaris on the cheeks and face in children
Appearance Both cheeks look faintly red and finely rough, sometimes spreading to the forehead and outer eyebrows. Parents often think it is baby acne or milk allergy rash.
Cause A subtype called keratosis pilaris faciei, often seen together with atopic dermatitis and a family history of allergy.
Severity/urgency Generally mild and improves with age, but watch for the type that thins the eyebrows and causes permanent pitting (keratosis pilaris atrophicans), which should be assessed early.
When to see a doctor When the outer eyebrows start to thin, when you see pits or small scars on the cheeks, or when the redness is so strong that the child scratches until the skin is broken. A child's facial skin is thinner, and acids or retinoids must not be used without consulting a doctor.
Keratosis pilaris-like bumps in the armpits and groin
Appearance Red bumps and small tender pustules appearing a few days after shaving or waxing, possibly with dark spots mixed in with new bumps.
Cause Almost always ingrown hairs and follicle inflammation from friction, not true keratosis pilaris. The skin here is thin, damp and constantly rubbing.
Severity/urgency Moderate, because there is a higher chance of secondary bacterial infection than at other sites, and this is the location that causes the dark underarms patients worry about a lot.
When to see a doctor When a bump grows into a painful lump under the skin, drains pus, recurs in the same place many times, or has small openings in the skin. This pattern must be distinguished from hidradenitis suppurativa, which is treated completely differently.
Keratosis pilaris on the buttocks and outer thighs
Appearance Rough bumps scattered over the buttocks and outer thighs. Some people have red bumps mixed in from friction with tight clothing and prolonged sitting.
Cause True keratosis pilaris together with pressure and dampness. Common in people who sit for long hours at work and in athletes who wear tight clothing.
Severity/urgency Low, but it is often mistaken for buttock acne and treated with acne spot medicine, which does not match the mechanism.
When to see a doctor When there are several pustules at once, pain, or on-and-off bumps lasting more than 3 months. A doctor should tell whether it is bacterial or fungal folliculitis, which needs anti-infective medication, not a keratin-dissolving one.
Other conditions that look like keratosis pilaris, and how to tell them apart
Folliculitis — Pustules around hairs, tender and soft, appearing quickly in crops, not rough skin that has stayed the same for years.
Miliaria (heat rash) — Small bumps that appear quickly in groups after sweating or a skincare change, usually itchy, and settling on their own within 1–2 weeks.
[Trichostasis spinulosa](https://www.siamdermatology.com/post/siw-sian-trichostasis-spinulosa) — A tuft of several dark hairs in a single follicle, usually on the nose and back, coming out as threads when squeezed.
Atopic dermatitis — Marked itching, red patches of skin with scratch marks, appearing mainly in the skin folds.
Molluscum contagiosum — Clear, shiny bumps with a dimple in the centre, slowly increasing in number and contagious.
Comedonal acne — Blackheads and whiteheads on the face, chest and back, not a symmetrical rough patch on the upper arms.
Can keratosis pilaris point to other diseases
Most of the time, keratosis pilaris is a stand-alone condition that does not signal any disease, but in some contexts a doctor will look for related problems. These include atopic dermatitis and fish-scale dry skin, which are very often found together, overweight and insulin resistance, which have been reported to be related to the severity of keratosis pilaris, and certain medications such as tyrosine kinase inhibitors or other drugs that make the skin very dry.
If keratosis pilaris appears suddenly in an adult who never had it, spreads quickly, or comes with weight loss, hair loss or irregular periods, that is a reason for further tests, not just applying medication.
Does keratosis pilaris go away on its own, and how long does it take
It partly goes away, but over years rather than weeks. The natural course that has been reported is:
It is usually most noticeable in the teens to the early 20s.
About 35–50% of patients improve clearly on their own after reaching age 30 or older.
In young children with it on the cheeks, most fade on their own before adolescence.
It fluctuates with the seasons, worse in winter and better in summer when the skin is better hydrated.
What needs to be understood clearly is that “improves on its own” is not the same as “cured”. The skin becomes less rough and the bumps flatten, but the follicles still tend to block easily as before.
How smooth can treatment make the skin — realistic expectations
This is the part most articles do not say plainly, so here it is in points.
What can really be done Reduce roughness, flatten the bumps, reduce the redness around them and reduce dark marks. The skin feels clearly softer.
Time needed You start to feel it softer at 2–4 weeks, see a clear result at 4–8 weeks, and need to keep applying to maintain it.
What still comes back If you stop the medication, the bumps usually return within 1–3 months, because the genetic mechanism of the follicle has not changed.
What still cannot be done There is currently no method that makes the skin of someone with keratosis pilaris permanently perfectly smooth without ongoing care. Be sceptical of anyone who guarantees a permanent cure.
Keratin-dissolving medications (Keratolytics) — the core of treatment
Apply a thin layer to the affected area once or twice a day, after a shower while the skin is still slightly damp, then layer a moisturiser on top. The medications with supporting evidence and available in Thailand are:
Urea 10–20% — The first choice. It dissolves keratin and holds water in the skin at the same time. It can be used from the upper arms to the legs, applied twice a day for 4–8 weeks. Concentrations of 20% and above dissolve keratin more strongly but sting more easily on thin skin. A sign that it is working is that the skin feels less rough when you stroke it at weeks 2–4.
Ammonium lactate 12% — The formula with the clearest randomised trial support for reducing skin roughness. Apply twice a day, with results in 4–8 weeks.
Lactic acid 5–12% — Gentler, suited to delicate skin and people who sting easily with strong urea.
Salicylic acid 2–6% — Dissolves keratin well in thick bumps, but should not be applied over very large areas in young children because it can be absorbed into the body.
Glycolic acid 5–10% — Similar results to the groups above, but it usually stings more on sensitive skin.
What shows it is not working: After 8 weeks of steady, consistent use the skin is just as rough, or it is red, stinging or peeling so much that you repeatedly have to stop. In both cases a doctor should adjust the plan, rather than you raising the concentration yourself.
Topical retinoids — for thick, resistant bumps
Used when a keratin-dissolving medication alone is not enough. They work by regulating cell shedding at the follicle opening from the start.
Tretinoin 0.025–0.05% or adapalene 0.1%, applied thinly at bedtime, starting 2–3 nights a week and then increasing the frequency as the skin tolerates it.
They must be used continuously for 8–12 weeks before the result can be judged properly.
Common side effects are dryness, peeling, stinging and redness at first, so they must always be applied together with a moisturiser and sunscreen.
Do not use during pregnancy or when planning a pregnancy, and use in children only under a doctor's supervision.
What shows it is working: The bumps flatten and dark marks fade in months 2–3, without ongoing red irritation of the skin.
Choosing which one to use, at what concentration and how often depends on the location, the thickness of the bumps, the state of the skin barrier and the patient's age, so it is a doctor's decision and prescription.
Skin barrier care — the part people skip but is the most necessary
Keratin-dissolving medication works fully only when the skin is not dry. Many people fail because they do not do this part completely.
Shower in lukewarm, not hot, water for no more than 10 minutes. Hot water strips the skin's oils and leaves it drier than before.
Use a gentle, fragrance-free soap or body wash. Avoid soaps that leave the skin squeaky tight.
Pat dry until slightly damp, then apply a moisturiser within 3 minutes while the skin is still moist.
Choose a moisturiser containing ceramides, glycerin or low-concentration urea, applied twice a day.
Use a humidifier, or spend less time in air-conditioned rooms when the skin is very dry.
For more on dry skin care, see the article Dry, cracked skin (Xerosis).
Fix the root cause for ingrown hairs — hair removal methods that really reduce the problem
If the problem is ingrown hairs, medication alone will not keep up. The hair removal method has to be fixed too.
Stop removing hair from that area for 3–4 weeks so that the buried hairs come out on their own. This is the most effective method and costs nothing.
If you must shave, shave with the grain, use a new sharp blade, do not pull the skin taut while shaving, and do not go over the same spot many times.
Always apply shaving cream or gel first, and apply a warm compress for 5 minutes before shaving if your hair is coarse.
Do not use a needle or tweezers to pull hairs out yourself, because this is the number one cause of dark marks and scars in this area.
Laser hair removal is an option with evidence that it reduces recurrent ingrown hairs in people with chronic problems, by reducing the number of hairs that can turn back into the skin in the first place. It takes several sessions spaced in cycles. Results vary from person to person, and it should be assessed and done by a doctor because of the risk of burns and dark marks in darker skin.
Other procedures for keratosis pilaris — useful, but not the first answer
Medical-strength chemical peels are used as an add-on for very thick bumps, done in cycles 2–4 weeks apart. They must be done by a doctor because of the chance of dark marks in Thai skin.
Vascular laser has data showing it helps reduce the redness around bumps in the predominantly red type, but it does not make the bumps disappear.
Fractional laser has been reported to help roughness and pitting in some cases, but the evidence is still limited and it is not standard treatment.
What to understand about all of them Every procedure is an add-on. It does not replace medication and skin barrier care, and it does not change the genetic tendency of the follicles.
Warning: Procedures to treat skin conditions carry a risk of not giving the expected results, and may cause harm or side effects. Results depend on the individual. They should always be assessed and performed by a doctor.
Things that make it worse the more you do them
Scrubbing hard with coarse-grain scrubs or scrubbing pads damages the skin barrier and makes the bumps redder. This is the most common mistake.
Squeezing, picking or poking the bumps gets a keratin plug out that comes back within days, but the dark marks stay for months.
Very hot and long baths leave the skin drier than before the moment you leave the bathroom.
Applying keratin-dissolving medication without following with a moisturiser makes the skin sting and peel, and you end up stopping the medication halfway.
Changing products every week because you do not see results yet. Keratosis pilaris needs 4–8 weeks. Switching back and forth means no product gets to work a full cycle.
Using steroid creams continuously on your own does not fix the keratin blockage, and with long use makes the skin thin with visible capillaries.
Dark marks and redness after keratosis pilaris — the real problem in Thai skin
In darker skin, what patients worry about more than the bumps themselves is the marks left behind, which come in two kinds and fade at different speeds.
Redness comes from dilated capillaries after inflammation, and usually fades on its own in 1–3 months if it is not provoked again.
Post-inflammatory dark marks (PIH) come from leftover pigment and take much longer, generally 3–12 months, and sun exposure significantly slows the fading.
What really helps is stopping the inflammation at its source, not picking, and applying sunscreen SPF 30 or higher every day on sun-exposed areas. Using pigment-lightening agents should be under a doctor's assessment. More detail is in the article Post-inflammatory hyperpigmentation (PIH).
Keratosis pilaris in children, pregnant women and sensitive skin
Young children Focus mainly on moisturiser and correct bathing. Low-concentration urea is acceptable. Avoid salicylic acid over large areas and do not use retinoids on the face on your own.
Pregnant and breastfeeding women Do not use topical retinoids. Use urea or lactic acid together with a moisturiser instead, and always tell your doctor before starting a new medication.
Sensitive skin and existing atopic dermatitis Get the existing rash calm first, then start a keratin-dissolving medication from a low concentration, applied every other day at first.
People with the predominantly red type Always start by repairing the skin barrier. Starting with a strong acid usually makes the redness worse and forces you to stop partway.
When to see a dermatologist
There is no improvement after 8 weeks of using a keratin-dissolving medication correctly and continuously.
There are pustules, red swelling, pain or fever, which suggest a secondary infection.
It appears on a child's face with thin eyebrows or pitting.
Keratosis pilaris appears suddenly in an adult who never had it, or spreads unusually fast.
There are accumulating dark marks or scars that affect your confidence.
Ingrown hairs recur in the same place every time after hair removal and are starting to become lumps or scars.
In short
True keratosis pilaris is keratin plugging the follicle opening, rough and symmetrical on the upper arms, thighs, buttocks and cheeks, not contagious and not dangerous.
Ingrown hairs are a different condition, appearing only where you shave or wax, with red tender bumps, and need the hair removal method fixed, not just medication.
The main medications are keratin-dissolving ones: urea 10–20%, ammonium lactate 12% or lactic acid 5–12%, applied twice a day together with a moisturiser. Assess the result at 4–8 weeks.
Topical retinoids are used for thick, resistant bumps, need 8–12 weeks, and must not be used in pregnancy.
It cannot be cured, but it can be controlled. It usually comes back within 1–3 months of stopping, and improves on its own with age in about half of patients.
What makes it worse is hard scrubbing and picking, not poor washing.
If you remember only one thing after reading: apply urea 10–20% followed by a moisturiser every day after your shower, for 8 weeks in a row, before deciding whether it works.
Frequently asked questions about keratosis pilaris
How do I get rid of keratosis pilaris?
The method with the clearest supporting evidence is a keratin-dissolving medication used consistently together with a moisturiser. The ones that are actually used are urea 10–20%, ammonium lactate 12% or lactic acid 5–12%, applied twice a day on skin that is still damp after a shower, then layered with a moisturiser. Give it at least 4–8 weeks before judging the result. If the bumps are still thick and resistant, a doctor may add a topical retinoid such as tretinoin or adapalene at bedtime. What needs to be understood is that “gone” in this condition means smoother, softer skin, not a permanent cure, because if you stop caring for it the bumps usually return within 1–3 months.
How many days does keratosis pilaris take to go away?
It is not a condition measured in days. If you start a keratin-dissolving medication correctly, you will begin to feel the skin less rough in about 2–4 weeks and see a clear result at 4–8 weeks. Red bumps or dark marks left from scratching and picking take much longer, with redness usually fading in 1–3 months and dark marks taking 3–12 months. In the long term, keratosis pilaris tends to improve on its own with age, with about 35–50% of patients clearly better after age 30. But if you have applied medication continuously for 8 weeks and see no difference at all, a doctor should assess whether it really is keratosis pilaris or another condition.
Do I need to pull keratosis pilaris bumps out?
No. Poking with a needle, pulling with tweezers or squeezing out the keratin plug and hair only works for a few days, because the same follicle builds a new plug by the same mechanism. What remains is inflammation and dark marks that take months to fade, and in some cases permanent scars, especially in the armpits, groin and shins. The right way is to soften the keratin plug so it comes away by itself with a keratin-dissolving medication, which does not injure the skin. If a coiled hair is clearly visible under the skin and inflamed, a doctor should remove it with sterile instruments.
Can I apply oil to keratosis pilaris?
You can, but it does not help fully. Oils form a coating that reduces water loss, so they can make the skin softer and reduce the rough feeling somewhat, but they do not dissolve the keratin plug blocking the follicle, which is the real cause of the bumps. If you use one, use it as an add-on after a keratin-dissolving medication such as urea or lactic acid, not as a replacement, and choose a fragrance-free type, because fragrance is a common cause of contact dermatitis. For people who also have pustules or inflamed follicles, some oils may make things worse, so consult a doctor first.
What is the difference between keratosis pilaris and ingrown hairs, and can I tell them apart myself?
In most cases you can. Look at three things. First, location: true keratosis pilaris is on the outer upper arms, thighs, buttocks and cheeks, symmetrically on both sides, while ingrown hairs appear only where you shave or wax, such as the armpits, groin and shins. Second, feel: keratosis pilaris is evenly rough and painless, while ingrown hairs usually have tender red bumps and some pustules. Third, history: keratosis pilaris has usually been there since childhood and runs in the family, while ingrown hairs appear after every hair removal. Telling them apart matters a lot, because ingrown hairs need the hair removal method fixed, while true keratosis pilaris needs continuous medication.
Can laser really treat keratosis pilaris?
It depends on which of two cases. If the problem is ingrown hairs from shaving or waxing, laser hair removal has evidence that it genuinely reduces recurrence, because it reduces the number of hairs that can turn back into the skin from the start, but it takes several sessions in cycles and results vary from person to person. If it is true keratosis pilaris, laser does not fix the keratin blockage, which is the root cause, so it is not the main treatment. Its only role is as an add-on, with vascular laser helping reduce redness around the bumps in the predominantly red type. In every case there is a risk of burns and dark marks, especially in darker skin, so it should be assessed and done by a doctor only.
Written by Dr. Patara Voravutinon, Dermatologist · Last reviewed 17 September 2026
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