How to Read a Sunscreen Ingredient Label
You’re standing in a drugstore aisle looking at 40 sunscreens. Several say “reef-safe.” A few say “mineral.” Most say nothing about their UV filter type at all. The front label is marketing. The back label is the actual document. Here’s how to read it.
Where to Find the UV Filters
The FDA classifies sunscreen as an over-the-counter drug. That means every bottle must list its UV-filtering compounds under “Active Ingredients” on the Drug Facts panel, separate from the inactive ingredients below. This is the section that tells you what type of sunscreen you’re holding.
Of the 16 UV filters currently allowed in U.S. sunscreens, the FDA has classified only two as GRASE (Generally Recognized As Safe and Effective): zinc oxide and titanium dioxide. Both are mineral filters. The remaining 14, including the six most commonly used chemical filters, are classified as Category III: insufficient data to confirm safety.
The Safe UV Filters
If the active ingredients section lists only zinc oxide and/or titanium dioxide, you’re holding a mineral sunscreen. These two compounds sit on the skin’s surface and physically reflect UV radiation rather than absorbing it.
Zinc oxide provides broad-spectrum protection across both UVA and UVB wavelengths. Titanium dioxide is effective against UVB and short-wave UVA but less so against long-wave UVA. Many mineral formulas combine both.
For reef safety, particle size matters. Look for “non-nano” on the label, indicating particles larger than 100 nanometers. Non-nano particles are too large for coral polyps to ingest. The National Park Service recommends non-nano mineral sunscreens for use near marine environments.
The Chemical UV Filters to Recognize
Chemical sunscreens make up 83% of the global sun care market by revenue. They absorb UV radiation and convert it to heat through a chemical reaction. Six chemical filters appear most frequently on U.S. labels:
| Active Ingredient | What to Know |
|---|---|
| Oxybenzone (Benzophenone-3) | Banned in Hawaii, Palau, and the U.S. Virgin Islands. Absorbs into blood above FDA safety thresholds after a single application. Documented coral bleaching agent. |
| Octinoxate (Ethylhexyl Methoxycinnamate) | Banned alongside oxybenzone in Hawaii. Disrupts thyroid hormones in fish, suppresses algae photosynthesis. A 2020 FDA study found blood levels 16 times above the agency’s safety threshold. |
| Avobenzone | Unstable under UV exposure; degrades unless paired with stabilizers. Detected at 9 times the FDA’s systemic exposure cutoff. Endocrine-disrupting breakdown products. |
| Homosalate | The European Commission’s Scientific Committee on Consumer Safety concluded homosalate is not safe at current use concentrations. Penetrates skin and may disrupt hormones. |
| Octocrylene | Degrades over time into benzophenone, a suspected carcinogen. Linked to marine toxicity affecting coral health. |
| Octisalate (Ethylhexyl Salicylate) | Absorbed systemically. Limited independent safety data. Often used as a stabilizer for avobenzone. |
If any of these names appear in the Active Ingredients section, the sunscreen uses chemical UV filters.
The Inactive Ingredients Trap
Some formulations include UV-filtering chemicals in the inactive ingredients section, where they serve as stabilizers rather than primary UV filters. Oxybenzone occasionally appears this way. The active ingredients section determines the sunscreen’s classification, but the inactive list can contain compounds with their own environmental profiles.
Preservatives like methylisothiazolinone and fragrance compounds also warrant attention in the inactive section, particularly for users with sensitive skin or those concerned about aquatic toxicity.
A Quick Decision Framework
Reading the label takes about 15 seconds once you know what to look for.
Step 1: Flip the bottle. Find “Active Ingredients” on the Drug Facts panel.
Step 2: Count the active ingredients. If you see only zinc oxide and/or titanium dioxide, the product is mineral-only.
Step 3: If you see any chemical filter names from the table above, the product uses chemical UV filters, regardless of front-label claims about being “reef-safe” or “mineral-based.” Some products blend mineral and chemical filters.
Step 4: For reef safety specifically, check for “non-nano” zinc oxide. If the label does not specify particle size, the manufacturer is not making that claim.
The EWG’s annual sunscreen guide rates individual products on both health and environmental criteria and is updated each year. For third-party reef-safety verification, look for the Protect Land + Sea certification seal from Haereticus Environmental Lab.
The ingredient list is the one part of the label a manufacturer cannot spin. Read it first.