The FDA has two categories that matter for sunscreen actives. Zinc oxide is in the right one.
The FDA regulates sunscreen as an over-the-counter drug. That means every active ingredient — every UV filter — is classified based on available safety and effectiveness data. There are three categories:
- Category I: Generally recognized as safe and effective (GRASE). Approved for use.
- Category II: Not GRASE. Not permitted.
- Category III: Insufficient data to classify. More information required.
Of the 16 UV filters currently used in sunscreens sold in the US, only two are Category I: zinc oxide and titanium dioxide. The other 14 — including oxybenzone, avobenzone, octinoxate, homosalate, and octocrylene — are Category III. The FDA has been requesting safety data on these actives for years. That data has not arrived.
That's not a marketing claim. It's the monograph.
Why Swellies uses zinc oxide as its only active
Zinc oxide is the only single mineral active that covers the full UV spectrum — both UVB and UVA — without needing a secondary active to fill in the gaps. Titanium dioxide covers UVB well but falls short on UVA. Chemical actives are often optimized for one or the other. Zinc oxide does both.
At 21%, Swellies is near the permitted maximum. That concentration is what delivers SPF 46 broad-spectrum protection from one ingredient, without anything else needed to make it work.
Non-nano: what it means and why it matters
Zinc oxide particles come in different sizes. Nano-sized particles are small enough to potentially penetrate the skin barrier. Non-nano particles are too large to do this. They sit on top of the skin and physically deflect UV radiation.
Swellies uses non-nano zinc oxide specifically. No systemic exposure. No chemical reaction on the skin. A clean physical barrier that works from the moment you apply it.
The five-ingredient logic
Most sunscreens have 20 to 30 ingredients because they're solving problems their own formula created. The active ingredients cause grease, so they add silicones. The silicones cause pilling, so they add texture modifiers. The whole formula becomes unstable, so they add preservatives. Every addition creates a new problem that requires another ingredient to solve.
Swellies was built from a different starting point: what is the minimum number of ingredients needed to deliver real SPF 46 protection without white cast, grease, or synthetic junk? The answer was five.
- Zinc Oxide (non-nano) 21% — the active. Full-spectrum UVA and UVB protection.
- Coco Caprylate/Caprate — lightweight plant-derived carrier. Replaces silicones entirely.
- Dextrin Palmitate — plant-derived binder. Provides water resistance and even coverage.
- Polyhydroxystearic Acid — castor oil-derived dispersant. Prevents zinc from clumping. Eliminates white cast.
- Iron Oxides — mineral pigment. Neutralizes residual white tone and blocks HEV (blue light).
No ingredient is there for appearances. Every one has a job.
What about the other 14 actives?
The FDA's position is precise: there is insufficient data to confirm they are safe for long-term use. That's not the same as unsafe — it means the science hasn't been submitted. We chose not to use them. Zinc oxide does the job, it's fully classified, and it's been used safely for decades. When one ingredient does everything you need and carries no open questions, there's no reason to reach for something that does.
Five ingredients. One FDA Category I active. Nothing to hide.