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Urea

Urea in skincare: Humectant below 10%, keratolytic above. What it does on skin, how strong the evidence behind the claim actually is, the concentrations in normal use, who reacts to it, and where it stands in pregnancy and sunlight. On a label it appears as Urea.

Hydration, emollients and barrier repairHumectant below 10%, keratolytic aboveEvidence: Strong

On the label: Urea. Also called: Carbamide.

This is an ingredient reference, not a diagnosis and not a treatment plan. It describes what substances are and what the published evidence supports; it does not tell you what your skin has or what to put on it. A rash that spreads, hurts, weeps, does not settle, or comes with feeling unwell is a reason to see a doctor or pharmacist, not to change serum.

What it is

A small molecule that is part of the skin's own natural moisturising factor, and one of the few ingredients whose behaviour changes completely with concentration. Cosmetic and pharmaceutical urea is synthesised industrially from ammonia and carbon dioxide; it is not collected from anything, which is worth stating plainly because the name puts people off.

What it does on skin

Below about 10% it acts as a humectant, binding water inside the outer layer and increasing its flexibility. At 10% and above it becomes keratolytic: it breaks down the keratin holding thickened, hardened skin together. That is why heel balms run at 20-40% and why 40% preparations are used to soften nails and thick calluses. One ingredient, two jobs, and the percentage tells you which one you bought.

What the evidence is worth

Evidence: Strong

Strong and long-standing in dermatology for dry, scaly and thickened skin, including the inherited scaling disorders and the rough bumps of keratosis pilaris. It is one of the ingredients where the clinical literature is older and deeper than the cosmetic marketing around it.

How it is used

A 5-10% cream for generally dry skin on body or face; 20-40% on heels, elbows and calluses, applied at night, ideally under a cotton sock. It works markedly better on skin that is still damp. For thickened heels, urea plus a pumice or foot file after a few days does more than either alone.

Typical concentration in normal use: 5% face and body, 20-40% feet. That is a description of the market, not a recommendation, and it is not a dose.

Who reacts to it

It stings sharply on fissured, cracked or inflamed skin — the deep cracks in a heel are exactly where people apply it and exactly where it burns. High-strength products are not for the face. On broken skin, heal the crack first with a plain ointment, then start urea.

Pregnancy and breastfeeding

Generally considered fine

No pregnancy concerns at cosmetic strengths. High-strength keratolytic preparations are worth mentioning to your midwife simply because they are closer to a medicine than a moisturiser.

Sunlight

No change

No effect on light sensitivity.

Rules and labelling

Permitted in cosmetics; the high-strength preparations for nails and calluses are often sold as medical devices or medicines rather than cosmetics, depending on the claim.

What it goes with, and what it does not

Urea and lactic acid together in a body lotion is one of the best-supported combinations for rough, dry skin. Under an occlusive layer or an overnight sock, effectiveness on heels roughly doubles for no extra cost.

One thing people get wrong

The myth is about where it comes from — the word alone convinces people it is an animal by-product. It is made from ammonia and carbon dioxide in a chemical plant, in the same process that makes agricultural fertiliser. The second and more useful correction: a 5% cream and a 40% heel balm are not strong and stronger versions of the same product, they do different things.

Sources: EU Cosmetics Regulation (EC) No 1223/2009 and its annexes, as published in the European Commission's CosIng database, for every statement about what is permitted, restricted or banned · opinions of the Scientific Committee on Consumer Safety (SCCS) and safety assessments of the Cosmetic Ingredient Review (CIR) for the concentration positions · standard dermatology reference material for mechanism, tolerability and contact-allergy patterns · checked 2026-09-06. Deep links are deliberately omitted where a stable public URL could not be confirmed.

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