Urea: Humectant at Low Levels, Keratolytic at High Levels

Urea is one of those ingredients where the percentage on your formula sheet quietly decides what kind of product you're making. At a couple percent, it's a humectant doing the same basic job as glycerin: pulling moisture into skin. Push it up toward the higher end of what's used in intensive foot creams and callus treatments, and it's functioning as a keratolytic, actively helping break down and soften thickened, hardened skin. Same INCI name, same CAS number, very different regulatory posture depending on what you say about it and how much you use.

The basics

Urea's INCI name is simply Urea, CAS number 57-13-6. It's a small, well-characterized molecule, not a botanical extract or a supplier blend, so there's no expansion math needed here the way there is with a fragrance or a proprietary complex. What you put on your ingredient list is exactly what's in the jar.

Why concentration changes everything

At the humectant end, urea behaves like any other moisturizing ingredient on a cosmetic label, and the claims you'd make (moisturizes, softens, hydrates) sit comfortably in cosmetic territory.

At the higher, keratolytic end, the function shifts toward actively altering the skin's structure rather than just supporting its surface hydration. This is where you want to be careful with claims. "Softens rough, dry skin" is a very different statement from "treats" or "removes" calluses. The latter starts to read as a drug-type claim (treating a condition) rather than a cosmetic claim (improving appearance or texture), and that distinction is exactly the line that separates a cosmetic from a drug in most markets. Sunscreen, anti-acne, and antiperspirant products are familiar examples of formulas that cross fully into drug territory because of what they claim to do, and an aggressive keratolytic claim can push a urea product toward that same boundary depending on the market and the specific wording used.

What this means for your notification

When you file a Cosmetic Notification Form listing urea, the ingredient itself isn't the complicated part, it's a known, permitted ingredient at typical cosmetic concentrations. What deserves your attention is:

1. Match your concentration to your claims. If you're at a humectant-level percentage, keep your marketing language in humectant territory. Don't borrow "callus removal" language for a light everyday lotion just because it sounds stronger.
2. Double check higher-concentration foot and heel products against drug/cosmetic boundaries. If a product is functioning as a keratolytic and the claims describe treating a skin condition rather than just softening texture, it's worth a second look at whether it's still squarely a cosmetic in your target market, since that line isn't the same everywhere.
3. Keep your formulation notes. If you ever need to explain why a product sits at a particular concentration, having that rationale (moisturizing support versus intensive softening) on hand is useful, especially if you sell the same brand at two different strengths for two different use cases.

A practical example

Say you sell a daily hand lotion and a separate heel balm, both listing urea. The hand lotion sits at a modest percentage aimed at daily comfort, no unusual claims. The heel balm sits meaningfully higher, marketed for cracked heels and rough patches. These are two different products with two different risk profiles even though the ingredient list overlaps heavily, and they're worth treating as genuinely separate filings with claims language reviewed separately, not just a single formula note with two SKUs attached.

Urea is a good reminder that INCI names and CAS numbers tell you what's in the bottle, but concentration and claims are what actually determine your regulatory category. Cosmetic Comply's ingredient screening carries your stated concentrations through the check against the current Hotlist and flags where an ingredient's use level or your claim language might need a closer look before the notification goes in, so this kind of concentration-driven distinction doesn't get missed on a busy product line.