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Urea

Also known as: carbamide

Urea is a water-binding molecule naturally present in skin's natural moisturising factor. Topical preparations use it for hydration and, in more concentrated formulations, softening thickened keratin. Its role depends on the finished product, the skin condition and the intended site.

In plain English — Urea helps the outer skin hold water. It is used in moisturisers for dry skin and in stronger preparations that soften thickened skin. Some particular urea-containing creams also have clinical evidence in eczema care.

Evidence status

Moderate

Urea has established moisturising and keratolytic uses. Controlled human studies support specific formulations in barrier-related measurements and eczema maintenance, with results determined by the comparator, formulation and clinical population.

What urea is, and the types available#

Urea, also called carbamide, is a small water-binding molecule. It occurs naturally in the outer skin as part of natural moisturising factor, the mixture of substances involved in retaining water within the stratum corneum. Topically applied urea can increase its water-holding capacity.[1, 4]

Its formulation range spans moisturisers and more concentrated keratolytic preparations. Creams and lotions are common vehicles; specialist uses include thickened skin and nail preparations. The useful distinction is the intended function — hydration, softening excessive keratin or an adjunct within treatment of a diagnosed disorder.[1]

The subject here is urea and its preparations. Stratum corneum explains the anatomy, skin barrier the function and TEWL the water-loss measurement.

Use of urea in aesthetic practice#

For a skincare professional, the main role is selecting supportive care for dry or rough skin. Urea offers a water-binding ingredient within an emollient; texture, tolerance and site remain important practical features of the complete product.[1][5]

Medicinal preparations also exist. For example, Balneum Plus combines urea with lauromacrogols for itchy, eczematous and scaling skin conditions requiring hydration or an antipruritic effect. Its indication belongs to that named medicine.[4] Aesthetic consultation can identify relevant products already in use and direct persistent symptoms to appropriate clinical assessment.[6]

Contraindications and cautions#

Consult the particular preparation’s product information. Balneum Plus excludes known ingredient hypersensitivity and acute inflammatory, oozing or infected lesions; it warns that broken or inflamed skin may burn. Eye and mucosal contact should be avoided for that preparation.[4]

Urea can increase penetration of other topical medicines. A client using a corticosteroid, dithranol or fluorouracil needs the relevant prescriber or pharmacist’s advice about combinations, rather than an assumption that any moisturiser is interchangeable.[4]

Pregnancy and breastfeeding wording is also preparation-specific. The Balneum Plus SmPC states that exposed-pregnancy clinical data are unavailable, while imposing no specific pregnancy restriction; it excludes breast application immediately before breastfeeding. This is label guidance for that combination, not a claim of pregnancy-trial evidence for the ingredient class.[4]

Clinical uses and the evidence behind them#

Dryness and experimental barrier response

A Perrigo-sponsored, observer-blinded study enrolled 49 adults with a recent history of atopic dermatitis. All completed four weeks of treatment on forearm areas that were clear of eczema at baseline. The within-person comparison included a cream containing 2% urea and 20% glycerol, a glycerol cream, a paraffin cream and an untreated site.[2]

After a standardised sodium lauryl sulphate challenge, the urea/glycerol cream produced a smaller increase in TEWL than no treatment: the between-condition difference was −9.0 g/m²/h, with a 95% confidence interval of −12.56 to −5.49. Hydration and clinical dryness also improved relative to selected comparators. These results describe adult forearm response following experimental irritation. Perrigo manufactured the two humectant creams and employed three coauthors.[2]

Maintaining improvement in atopic eczema

Åkerström and colleagues randomised 172 adults aged 18–82 after their eczema had cleared or almost cleared with initial treatment. Previously affected body areas were followed for relapse for up to 180 days. A 5% urea cream, Canoderm, was compared with a reference cream made without glycerol; the formulas differed in several other constituents too.[3]

The adjusted hazard ratio for relapse was 0.634, with a 95% confidence interval of 0.446–0.901. Median time to relapse was 22 days with the test cream and 15 days with the reference. This supports that preparation’s maintenance role after control of inflammation. ACO Hud Nordic sponsored the trial, contributed to its design and data collection, and employed several authors; the Swedish Knowledge Foundation provided part funding.[3]

Thickened and scaling skin

Urea also has an established keratolytic role in dermatology. More concentrated preparations are used to soften excessive keratin, including in selected palmoplantar and nail conditions. Diagnosis, site and the intended product govern that use.[1] These specialist applications are distinct from choosing a routine facial moisturiser.

Selecting a urea-containing preparation#

Begin with the problem being addressed: straightforward dryness, symptomatic eczema under treatment, or a thickened lesion requiring diagnosis. Then consider the formulation’s intended site, vehicle, acceptability and other active ingredients. Emollient selection often depends on which preparation is comfortable enough for the individual to use consistently.[1][5]

For a disease-related claim, the most useful evidence identifies a comparable patient group and a comparable finished preparation. For a cosmetic product, selection should follow its intended use. Concentrations reported here describe studies and products; they do not supply an escalation schedule.[2, 3]i[4]

Adverse effects and their management#

Burning, irritation or a new eruption requires reassessment of the product and the skin condition. The Balneum Plus information lists local reactions including burning and erythema; any reaction could concern the combination or its excipients, rather than proving urea allergy.[4] Persistent stinging or a rash with an emollient warrants advice from a pharmacist, nurse or doctor.[5]

Stop exposure to a suspected cause of contact dermatitis while arranging appropriate advice. Record the complete product, site and timing. Medical assessment is needed when symptoms are severe, recurrent or persistent.[6]

The usual emollient fire precaution applies: product residue in clothing, dressings and bedding can make fabrics ignite more readily, including with paraffin-free formulations. Keep contaminated fabrics away from smoking and flames; laundering does not completely remove the risk.[5]

Referral and scope boundaries#

Persistent inflammatory or scaling disease needs diagnosis rather than a succession of stronger products. NHS advice recommends medical assessment for recurrent, persistent or severe dermatitis.[6] An infected or oozing lesion is outside the intended use of the named medicine described here.[4]

Clinical management of eczema, nail disease and substantial hyperkeratosis belongs within the relevant professional’s competence. The positive eczema maintenance trial began after treatment of inflammation; it describes an adjunctive care setting.[3] No instructions are supplied here for treating a lesion, removing a nail or combining urea with a prescription medicine.

Mechanism of action#

The moisturising role follows urea’s affinity for water and its presence within natural moisturising factor. Applied urea can increase the stratum corneum’s ability to hold water.[1, 4]At greater concentrations, changes in keratin’s hydrogen bonding and protein structure contribute to softening and keratolysis.[1]

The formulation determines how these properties are delivered alongside its other components. For example, the forearm study assessed a urea/glycerol cream that also contained additional emollient ingredients. The measured changes in water loss and hydration describe the behaviour of the skin after that complete treatment.[2] The general mechanistic review is manufacturer-authored, with ISDIN employment, consultancy and publication-fee support disclosed.[1]

Commonly misstated claims#

Complete formulations and ingredient effects

Claim heard:“A urea cream trial proves the benefit comes from urea alone”

Literature finding:The forearm trial’s test cream contained glycerol and other ingredients. The eczema maintenance trial compared different complete formulas, not the same base with and without urea.[2, 3]i

Supported statement:These trials support their tested formulations; they do not isolate every ingredient’s contribution.

Relative relapse hazards

Claim heard:“A 37% reduction means 37 more people out of 100 stay eczema-free”

Literature finding:The maintenance study’s headline reduction comes from the hazard ratio, describing relative relapse rates over follow-up. It is not a 37-percentage-point absolute benefit. The reported hazard ratio was 0.634, with 95% CI 0.446–0.901.[3]i

Supported statement: Report the relative hazard, its confidence interval and comparator, rather than recasting it as an absolute success rate.

Barrier measurements and eczema outcomes

Claim heard:“Lower TEWL after an irritant challenge proves fewer eczema flares”

Literature finding: The forearm experiment measured response to a detergent challenge. Time to clinical eczema relapse was assessed in a different trial, with a different cream and population.[2, 3]i

Supported statement: Barrier-related measurements and clinical relapse outcomes are useful but distinct evidence.

Areas of remaining uncertainty#

  • Site-specific choice: adult forearm findings and maintenance care of previously affected body areas leave further questions about the best vehicles for particular sites. Product selection should match the intended site and skin presentation.[2, 3]i
  • Acceptability over time: the relationship between comfort, texture preference and sustained use deserves attention alongside clinical endpoints. A preparation that is unsuitable for the individual should be reassessed rather than selected solely from an efficacy result.[3][5]
  • Broader populations:the maintenance trial enrolled adults and excluded pregnancy and breastfeeding. Evidence transfer to those settings requires population-appropriate guidance, with the named product’s information checked.[3][4]

Frequently asked questions#

Why do some urea products moisturise while others soften thick skin?

Both functions relate to the molecule’s interaction with water and keratin. Concentration and the rest of the formulation affect the intended role.[1]

Is urea found naturally in skin?

Yes. It is present in skin and contributes to water retention in the outer layer.[1, 4]

Where does this fit beside panthenol and ceramides?

These are separate ingredient entries that address different formulation components. See panthenol for that humectant and ceramides for the lipid family. Selection of a complete moisturiser also considers vehicle and individual tolerance.[5]

References#

Each source is graded by evidence tier. Tier 4 material (manufacturer documents, expert consensus, practitioner experience) is useful for protocol and context, and is never presented as equivalent to independent clinical evidence.

  1. Piquero-Casals J, Morgado-Carrasco D, Granger C, Trullàs C, Jesús-Silva A, Krutmann J. Urea in Dermatology: A Review of its Emollient, Moisturizing, Keratolytic, Skin Barrier Enhancing and Antimicrobial Properties. Dermatol Ther (Heidelb). 2021;11(6):1905–1915. doi:10.1007/s13555-021-00611-y. PMID:34596890.Tier 4Supports: Ingredient identity, water-binding and keratolytic roles, formulation types and dermatological context.Funding / interest: Manufacturer-authored: Granger and Trullàs employed by ISDIN; Piquero-Casals, Morgado-Carrasco and Krutmann received ISDIN consultant fees. ISDIN supported the journal's Rapid Service Fee. Narrative review, not a systematic review or direct clinical experiment.
  2. Danby SG, Andrew PV, Taylor RN, et al. Different types of emollient cream exhibit diverse physiological effects on the skin barrier in adults with atopic dermatitis. Clin Exp Dermatol. 2022;47(6):1154–1164. doi:10.1111/ced.15141. PMID:35167133.Tier 2Supports: Four-week within-person forearm comparison and response to experimental SLS challenge.Funding / interest: Sponsored and funded by Perrigo Nordic, manufacturer of the urea/glycerol and glycerol creams. Fasth, Carlander and Holm were employees; Danby and Cork disclosed multiple industry relationships, including Perrigo. Full XML retrieved through Europe PMC.
  3. Åkerström U, Reitamo S, Langeland T, et al. Comparison of Moisturizing Creams for the Prevention of Atopic Dermatitis Relapse: A Randomized Double-blind Controlled Multicentre Clinical Trial. Acta Derm Venereol. 2015;95(5):587–592. doi:10.2340/00015555-2051. PMID:25594845.Tier 2Supports: Adult eczema maintenance trial with product-specific hazard ratio and confidence interval.Funding / interest: Sponsored by ACO Hud Nordic and partly funded by the Knowledge Foundation, Sweden. Åkerström, Wirén and Skare were ACO employees; Grände was an employee during the study. Sponsor responsible for design, coordination and data collection; other ACO consulting/lecture/research relationships disclosed. Original article retrieved from Lund University.
  4. Almirall. Balneum Plus Cream: Summary of Product Characteristics. Text revised 23 September 2019. Sections 2, 4.1, 4.3–4.6, 4.8 and 5.1. Accessed 16 September 2026.Tier 1Supports: Named medicine's composition, indication, contraindications, interactions and pregnancy wording.Funding / interest: Manufacturer's approved product information; not independent class-wide clinical evidence.
  5. NHS. Emollients. Public patient guidance. Accessed 16 September 2026.Tier 4Supports: Vehicle selection, reactions, clinical advice and emollient fire risk.Funding / interest: NHS public guidance, not an ingredient-sponsored study.
  6. NHS. Contact dermatitis. Reviewed 3 May 2023. Accessed 16 September 2026.Tier 4Supports: Medical assessment for persistent, recurrent or severe dermatitis.Funding / interest: NHS public guidance, not an ingredient-sponsored study.