Urea is a highly versatile and clinically effective ingredient in the topical management of psoriasis. It is not merely an inert moisturizer; it is a naturally occurring component of the skin’s own moisturizing system and possesses powerful properties that directly address the core symptoms of psoriatic plaques: dryness, scaling, and thickening.
1. The Humectant Role: Deep Hydration
One of the defining features of psoriatic skin is a compromised skin barrier and significantly reduced levels of natural moisturizing factors (NMFs)—of which urea is a key component. This leads to profound dryness, cracking, and flaking.
- Attracting and Retaining Water: Urea is a potent humectant. It is highly hygroscopic, meaning it has the ability to attract and hold water molecules from the deeper layers of the skin (dermis) and the environment, drawing them into the outermost layer (stratum corneum).
- Restoring the Barrier: By increasing the water content of the skin, urea restores flexibility and integrity to the skin barrier. This alleviates the uncomfortable dryness and tightness associated with psoriatic plaques and can help to reduce associated itchiness (antipruritic effect).
This moisturizing effect is most prominent at lower concentrations (typically 2% to 10%).
2. The Keratolytic Action: Scale Removal
The excessive, rapid turnover of skin cells in psoriasis leads to the buildup of thick, stubborn scales. This phenomenon is known as hyperkeratosis.
- Softening the Keratin: At higher concentrations (typically 10% to 40%), urea acts as a keratolytic agent. It works by gently disrupting the hydrogen bonds within the protein keratin, which forms the structure of the skin. This effectively “dissolves” the cellular cement holding the dead, scaly cells together.
- Shedding the Plaques: The result is the softening and shedding of thick psoriatic scales and rough patches, visibly reducing the thickness of the plaques and improving skin texture.
For moderate to severe scaling in psoriasis, formulations containing 20% or more are often required to achieve a strong keratolytic effect.
3. Enhancing Therapeutic Penetration
Like salicylic acid, urea is highly valued for its ability to act as a penetration enhancer.
- Optimizing Combination Therapy: By first softening and removing the thick, dry scales, urea creates a clearer pathway for other prescribed topical medications—such as corticosteroids or vitamin D analogues—to penetrate deeper into the skin where inflammation is active. This synergistic action can significantly boost the overall efficacy of a psoriasis treatment regimen.
Using Urea in Psoriasis Care
Urea is incorporated into a wide range of topical products, including creams, lotions, and ointments.
| Concentration Range | Primary Action | Clinical Use in Psoriasis |
| 2% – 10% | Humectant / Moisturizer | Daily maintenance, general dryness, and skin barrier support. |
| 10% – 30% | Keratolytic (Scale Removal) & Humectant | Treatment of hyperkeratotic plaques and severe scaling. |
| > 30% | Strong Keratolytic / Proteolytic | Severe, localized thickening (e.g., palms, soles, nails). |
Note on Tolerance: While generally well-tolerated, higher concentrations of urea may sometimes cause a mild, temporary stinging or burning sensation, especially on sensitive or broken skin. Patients should consult their dermatologist to determine the appropriate concentration and usage schedule for their specific condition.
In essence, urea offers a two-pronged attack against psoriasis: it fixes the underlying dryness common in psoriatic skin while simultaneously breaking down the hallmark scaling, making it an indispensable component of comprehensive topical psoriasis care.