Zinc Oxide in Cosmetics: INCI, CAS, and When It Becomes a Drug

Zinc oxide sits in this odd middle ground where the exact same white powder can be a perfectly ordinary cosmetic ingredient in one product and a regulated drug active in another, purely based on what you say it does. That distinction catches a surprising number of small makers, especially anyone building a mineral makeup or barrier cream line who reaches for zinc oxide without thinking through the claims angle.

The basics

Zinc oxide's INCI name is simply Zinc Oxide, and its CAS number is 1314-13-2. It's a white, insoluble mineral powder used widely across cosmetics for a few different jobs:

• Pigment and opacifying agent in mineral makeup, powders, and some skin tints, where it contributes coverage and a matte finish.
• Skin protectant function in barrier-type products, where it can help form a physical layer, which is part of why it's such a common ingredient in diaper rash creams and similar products.
• UV filter when the claim and formulation are built to make it function as sunscreen.

That last use is where things change.

Where the line actually sits

In the United States, sunscreen is regulated as an OTC drug, not a cosmetic, regardless of what the active ingredient is made of. Zinc oxide is one of the ingredients recognized for sunscreen use, but the moment you formulate a product and market it with an SPF claim, or otherwise claim it protects against sun damage, you've stepped into drug territory. That triggers a completely different regulatory pathway than a standard cosmetic notification or listing, with its own testing, labeling, and manufacturing expectations.

This same logic, that the claim determines the category more than the ingredient does, shows up again and again across cosmetic regulation generally. A soap made from alkali salts of fatty acids can be sold as "true soap" with only a cleansing claim and treated differently from a cosmetic. The instant that same bar claims to moisturize, fight acne, or soften skin, it's a cosmetic, full stop, subject to cosmetic notification and labeling rules. Zinc oxide follows the same pattern, just crossing into drug territory instead of cosmetic territory.

Practical claim boundaries for zinc oxide products

Product framing	Regulatory category	Why
"Mineral pigment for natural coverage"	Cosmetic	Claim describes appearance, not protection or treatment
"Soothing barrier cream"	Cosmetic	Claim describes a cosmetic-level physical effect
"Broad spectrum SPF 30"	OTC drug	Explicit sunscreen/SPF claim
"Provides sun protection"	OTC drug	Implied sun protection claim, even without a stated SPF number
"Helps calm diaper rash"	Likely drug territory	Treatment-style claim, worth specific regulatory review

If your product description reads anything like "protects from sun" or references SPF, UVA, or UVB, treat that as a hard signal you're in OTC drug territory and need to work through that pathway rather than a standard cosmetic filing, even if zinc oxide is your only active ingredient of concern.

Filing zinc oxide as a cosmetic ingredient

Assuming your claims stay squarely cosmetic (a mineral powder foundation, for instance), zinc oxide gets listed on a Canadian Cosmetic Notification Form by its INCI name, Zinc Oxide, with the concentration or range you're using, same as any other ingredient. It's not something makers typically need to second-guess against the Hotlist at normal cosmetic pigment or barrier-function levels, but always worth confirming against the current Hotlist if your concentration is unusually high or your product type is unusual.

The takeaway for anyone reformulating

If you're adjusting a formula's zinc oxide level or adding it to a new product, pause and ask what claim you're actually planning to make before you touch the percentage. The ingredient itself doesn't change, but your regulatory obligations swing hard depending on whether you're marketing coverage and barrier support or marketing sun protection.

Cosmetic Comply's ingredient matching flags zinc oxide correctly by INCI and CAS number as part of a standard Canadian filing, and part of what a good compliance review should catch is exactly this kind of claim-versus-ingredient mismatch before it becomes a bigger problem down the line.