TL;DR
Keratosis pilaris is caused by keratin building up and plugging hair follicles, mostly because of genetics. Dry skin, eczema, allergies and cold weather make it worse, while hygiene has nothing to do with it. You cannot prevent it, but moisturizer, gentle exfoliation and a retinoid can keep the bumps in check.
What causes keratosis pilaris? In plain terms, your skin makes too much keratin (a hard protein that protects skin) and it clogs the openings of your hair follicles. That is the whole mechanism. The rough, sandpapery bumps are tiny keratin plugs with a hair sometimes trapped underneath.
The harder question is why your follicles do that. Here is what researchers and dermatologists know, and what is still guesswork.
Is keratosis pilaris genetic?
Mostly, yes. KP often runs in families, and if one parent has it, you are much more likely to have it too. Studies suggest it can follow a dominant pattern in some families, which means one copy of the responsible gene can be enough.
One genetic link that scientists have studied is the filaggrin gene (FLG), which helps build the skin barrier. Variants in this gene are connected to dry skin, eczema and some forms of KP. That helps explain why these conditions travel together.
The practical takeaway: you did not cause it, and nothing you did as a kid brought it on.
Why does keratin build up in the follicle?
The exact trigger is not fully understood. The leading idea is that the skin's lining of the follicle sheds in a thicker, stickier way than normal, so dead cells clump together instead of sloughing off. They form a plug that traps the hair.
Inflammation around the plug explains the pink or red halo many people see. In deeper skin tones, the same inflammation can leave a brownish tint.
What makes keratosis pilaris worse?
You cannot change your genes, but you can change what aggravates them. These are the usual culprits.
| Trigger | Why it matters | What to do |
|---|---|---|
| Dry air and winter | Low humidity dries out skin and thickens keratin | Humidifier, thicker moisturizer |
| Hot, long showers | Strips oils, worsens dryness | Lukewarm water, 10 minutes or less |
| Harsh soaps | Disrupt the skin barrier | Fragrance-free gentle cleanser |
| Scrubbing and friction | Inflames follicles | Soft washcloth, no loofah |
| Shaving and waxing | Irritates plugged follicles | Sharp blade, shave cream, gentle technique |
| Eczema or allergies | Skin barrier is already weak | Treat the eczema; see your doctor |
Who gets keratosis pilaris?
KP is very common. It tends to start in childhood, peak in adolescence and often improves in adulthood. Some surveys put it at around four in ten adults, and higher in teens, though the numbers vary between studies.
It is more common in people with:
- A family history of KP.
- Dry skin or ichthyosis vulgaris (a very dry skin condition).
- Eczema (atopic dermatitis), asthma or hay fever.
- Overweight, in some studies.
- Fair skin, where the redness shows more, though it affects all skin tones.
Hormones may play a role too. Many people notice flares during puberty and sometimes during pregnancy, while others see it improve.
Does keratosis pilaris come from something you eat or do?
No credible research shows that a food causes KP. Some online posts blame gluten, dairy or vitamin A, but those claims are weak. Severe vitamin A deficiency can cause a different follicular skin problem, but it is rare in people with normal diets. We go deeper in keratosis pilaris and diet.
Poor hygiene does not cause KP either. Over-washing, in fact, tends to make it worse by drying the skin.
Myth check: KP is not an infection, not contagious and not caused by clogged pores from dirt. It is a quirk of how your skin sheds.
How do you tell keratosis pilaris from other bumps?
KP bumps are small, uniform and rough, usually on the outer arms and thighs, and not painful. Other conditions to rule out include folliculitis (sore, pus-filled bumps), eczema (itchy, scaly patches) and acne. These comparisons can help:
If you are unsure, a doctor can usually diagnose KP by looking at it.
Why is keratosis pilaris worse on some body parts?
KP favors the outer upper arms, the front and sides of the thighs, the buttocks and, in some people, the cheeks. These areas have many fine hair follicles and tend to be dry. Elbows, forearms and the backs of the calves are less typical but still possible.
Friction and shaving can make a given spot more obvious. If you want area-specific advice, see keratosis pilaris on arms and keratosis pilaris on legs and thighs.
Does sun exposure or climate change KP?
Many people find KP calmer in summer and rougher in winter. Warm, humid air keeps skin hydrated, and a little sun can make bumps less noticeable. Dry indoor heating and cold wind do the opposite. This seasonal swing is one of the clearest clues that moisture plays a big role, even though it is not the root cause.
Can you treat what causes keratosis pilaris?
You cannot fix the genetics, but you can treat the keratin build-up. That is what the effective ingredients do.
- Urea and lactic acid: Hydrate and loosen keratin. See urea cream for keratosis pilaris.
- Salicylic acid: Dissolves plugs within the follicle. See salicylic acid for keratosis pilaris.
- Retinoids: Normalize how skin cells shed so plugs form less often. See tretinoin for keratosis pilaris.
The ranked version, with honest pros and cons, is in our guide to the best keratosis pilaris treatments.
What should you buy if the cause is keratin and you want it gone?
For mild cases, start with a urea or lactic acid moisturizer. If it has been 8 to 12 weeks and the bumps are still there, you are in prescription territory, because the problem is plug formation, not just dryness.
Vuret KP Flare Control Cream targets each part of the cause in one compounded cream: urea 20%, lactic acid 10%, salicylic acid 2% and tretinoin 0.025%. A U.S.-licensed physician reviews a short online visit and prescribes it only if appropriate, and you pay for medication only if approved. Compounded medications are not FDA-approved, tretinoin is not for pregnancy, and the cream is prescribed to adults.
See a doctor in person if your skin is painful, infected or changing quickly. For further reading, see the AAD overview of keratosis pilaris and DermNet.
If you are ready to treat the cause, you can start an online visit for KP Flare Control Cream.
KP Flare Control Cream: Urea 20% + Lactic Acid 10% + Salicylic Acid 2% + Tretinoin 0.025%
Urea 20%, lactic acid and salicylic acid dissolve the plugs while tretinoin keeps follicles clear. Prescribed online by a U.S.-licensed physician only if it is right for you. Compounded medications are not FDA-approved.
See KP Flare Control CreamFrequently asked questions
What is the main cause of keratosis pilaris?
Keratin builds up and plugs hair follicles. Genetics is the biggest driver, with dry skin and eczema making it more likely.
Is keratosis pilaris caused by poor hygiene?
No. KP has nothing to do with cleanliness, and over-washing or scrubbing can actually make it worse.
Is keratosis pilaris hereditary?
Often. It commonly runs in families, and having a parent with KP raises your chance of having it.
Does a vitamin deficiency cause keratosis pilaris?
There is no good evidence that common vitamin shortfalls cause typical KP. Severe vitamin A deficiency can cause a related follicle problem, but that is rare and different.
Why did my keratosis pilaris start suddenly?
It often becomes more noticeable at puberty, with dry weather or after skin irritation. If bumps appeared suddenly, are painful or spread quickly, see a doctor to rule out other conditions.