Urea

Happy 250th birthday, urea—an ingredient which is sorely misunderstood, though to those who know of its powers, would be sorely missed if by some cruel twist of fate or supply chain disruption, it were to ever disappear. A tiny molecule with huge moisture-retaining and exfoliating benefits, it might be the most under-appreciated skincare ingredient out there. Let's change that. Today, we honor you…ree-uh.

This natural compound is most commonly known for its unglamorous origin story: It was discovered in pee in 1773.¹ In the body, the liver converts toxic ammonia into urea, which is then filtered out by the kidneys as urine. Because urea is highly water soluble and absorbent—and because we create a lot of it every day—it concentrates in your pee so you can get rid of large quantities of it without having to use the bathroom constantly.

In skincare, it’s known for being an effective humectant, an ingredient that helps the skin retain moisture. But to answer your next question: No, the urea used in skincare products is not derived from urine, and hasn't been for two centuries. Synthetic urea was first created by chemist Friedrich Wöhler in 1828, a discovery that helped define the field of organic chemistry as we know it. It was the very first organic compound to be synthesized from an inorganic source, meaning no living organisms were required to make it. Wöhler’s ureic legacy was so renowned that his death was commemorated with a German postal stamp featuring the molecular structure of urea—a major upgrade in its relationship with household paper goods.²

Urea is also hygroscopic, which means it has a powerful ability not just to moisturize the skin, but to penetrate the skin barrier and hold onto water. It helps keep the skin hydrated over time. Water-attracting materials like hyaluronic acid, glycerin, and aloe vera (which have had more successful PR campaigns than urea) function similarly, attracting moisture and retaining it within skin cells.⁴

What makes urea unique is that, at certain concentrations, it also exfoliates and softens the skin as a keratolytic agent. Other keratolytic ingredients you might be familiar with are salicylic acid, lactic acid, and glycolic acid. This category of molecules loosen dead skin cells on the outer layer of your epidermis (the stratum corneum), allowing for them to easily be buffed or washed away, leaving a smoother surface. And because urea is a familiar compound in the body, it’s less likely to irritate the skin in the process, making it a reliable exfoliant choice for dry and sensitive skin.^5,6

That said, the quantity of urea in a skincare product changes its function. Some lotions and creams contain a small percentage of urea to enhance their moisturizing and softening ability. Higher percentages increase the exfoliant, or keratolytic, effects.^4,5

- 2% — 12% urea improves water retention in skin and loosens dead skin cells.

- 20% — 30% urea significantly improves skin barrier function and reduces tough, callused skin.

- 40% — 50% urea is used for targeted spot treatments (often for feet) to reduce hard calluses, corns, and extra thick, dry, cracked skin.