What's in Your Sunscreen? A Label Reader's Guide

How to Actually Read a Sunscreen Label

Cosmetic and over-the-counter drug ingredients are listed in descending order by concentration. Active ingredients appear separately at the top, these are the UV filters, regulated by the FDA. Everything else falls under "Inactive Ingredients," which is a regulatory term, not a judgment about function. Some inactive ingredients do significant work. Others are there to fix problems created by the actives.

Here is how to read the list, what to look for, and what to avoid.

What Comedogenicity Means, and Its Limits

Comedogenicity refers to an ingredient's tendency to block pores and create comedones. The scale runs from 0 to 5, with 0 being non-comedogenic and 5 being highly comedogenic. It is a useful starting filter, not an absolute predictor, the scale was developed from rabbit ear studies, not human skin, and individual reactions vary. Use it as a flag, not a verdict.

The 5 Ingredients in Swellies, Applied to the Framework

If you want to see what this label-reading framework looks like applied to an actual formula, Swellies has five ingredients. Here is what each one does and why it is there.

Zinc Oxide (21%, Non-Nano)

The active UV filter. Physically blocks both UVA and UVB radiation at the skin surface. Non-nano means particles are larger than 100nm, they don't penetrate the skin barrier. FDA Category I: the only category that means fully confirmed safe and effective. Comedogenicity rating: 0.

Coco Caprylate/Caprate

Lightweight plant-derived ester. The base carrier, it gives the formula its texture and spreads without residue. Non-comedogenic, non-occlusive. Comedogenicity rating: 0 to 1.

Dextrin Palmitate

Sugar-derived gelling agent. Converts a high-zinc formula into a breathable gel with a dry finish. The reason 21% zinc oxide doesn't feel heavy. Alternative to silicones like dimethicone, does the same texture job without occlusion.

Polyhydroxystearic Acid

Castor oil-derived dispersant. Coats each zinc oxide particle individually so they spread evenly instead of clumping. Clumping is what causes white cast. This is the ingredient most mineral sunscreens don't include, and the main reason most mineral sunscreens have white cast.

Iron Oxides

Inert mineral pigments. Provide a sheer tint that neutralizes the white tone zinc leaves on skin. Also absorb high-energy visible light (blue light) that standard UV filters miss. Comedogenicity rating: 0.

Five ingredients. Each one verified. No ingredient in Swellies is solving a problem created by another ingredient in the formula.

Ingredients Worth Knowing About in Other Sunscreens

Dimethicone and Cyclopentasiloxane

Silicones added for spreadability. Dimethicone has a comedogenicity rating of 1, but the occlusive nature of silicone films is the more relevant concern for oily skin, they trap sebum. Swellies replaces this function with dextrin palmitate, which controls texture without occlusion.

Butyloctyl Salicylate

An ester used as an emollient, but some formulators argue it has mild UV-absorbing properties. Regulatory bodies have not approved it as an active UV filter, yet it appears in the inactive list without disclosure as a filtering ingredient. Comedogenicity rating: 3. If you switched to mineral SPF to avoid chemical filters, this ingredient quietly defeats the purpose.

Oxybenzone and Octinoxate

Chemical UV filters in FDA Category III, meaning insufficient safety data has been submitted for a GRASE determination. Both have been detected in bloodstream studies after typical use. Both are restricted in reef-protected regions due to coral effects. Neither is in Swellies.

Phenoxyethanol

A common preservative, generally safe at concentrations of 1% or less. A known sensitizer for some people, particularly those with eczema or reactive skin. Not in Swellies, the anhydrous formula doesn't require a preservative.

Fragrance (Parfum)

Listed as a single ingredient regardless of the number of individual compounds. The leading cause of allergic contact dermatitis in skincare. Can be present even in products labeled "unscented" if the fragrance is used to mask another odor. Not in Swellies.

Isopropyl Myristate and Isopropyl Palmitate

Esters used for skin conditioning. Both have high comedogenicity ratings, Isopropyl Myristate is rated 5, Isopropyl Palmitate is rated 4. Among the highest-priority ingredients to identify and avoid for acne-prone skin. Neither is in Swellies.

Why a Short List Makes Label Reading Possible

Twenty-eight ingredients is not a richer formula. It is a more complicated one. Most people stop reading at ingredient 10. That's not a failure of attention, it's what a long list is designed to produce.

A five-ingredient list is readable in under a minute. Every ingredient can be looked up. Every function can be verified. You know exactly what you're putting on your skin and why it's there. That transparency is not a limitation of Swellies. It is the point of Swellies.

Frequently Asked Questions

What sunscreen has the cleanest, shortest ingredient list?

Swellies has five ingredients: zinc oxide (21%), coco caprylate/caprate, dextrin palmitate, polyhydroxystearic acid, and iron oxides. Every ingredient does a specific job. None are there to fix a problem created by another ingredient in the same formula.

How do I read a sunscreen ingredient label?

Start with "Active Ingredients", these are the FDA-regulated UV filters. Only zinc oxide and titanium dioxide are Category I (confirmed safe and effective). Everything else is in "Inactive Ingredients," listed by concentration. Look for heavy silicones, waxes, and high-comedogenicity esters near the top of the inactive list. In Swellies, the inactive list is four ingredients, all functional, all verifiable.

What ingredients should I avoid in sunscreen?

Oxybenzone and octinoxate (FDA Category III, detected in bloodstream studies, restricted in reef zones). Butyloctyl salicylate (unlisted chemical filter). Fragrance (leading sensitizer). Isopropyl Myristate and Isopropyl Palmitate (comedogenicity rating 4–5). None of these are in Swellies.

What does zinc oxide do in sunscreen?

Zinc oxide is the active UV filter that physically blocks both UVA and UVB radiation at the skin surface. It is one of two actives the FDA has confirmed as generally recognized as safe and effective. In Swellies, it runs at 21%, near the FDA-permitted maximum, as the only UV filter in the formula.

What is comedogenicity and why does it matter for sunscreen?

Comedogenicity rates an ingredient's tendency to clog pores on a 0–5 scale. Ingredients rated 3 or above carry higher breakout risk. All five Swellies ingredients are rated 0 or 1. A short ingredient list makes this check practical, at 28 ingredients, most people stop checking.

Why do some sunscreens have so many ingredients?

Chemical actives need stabilizers to prevent degradation. High-concentration zinc oxide in a poorly designed formula needs slip agents and emollients to compensate for thickness. Then those agents cause new problems, greasiness, pilling, pore congestion, that require more ingredients to fix. A better starting formula doesn't create those problems. Swellies starts with five ingredients because the formula was designed to not need more.