Frequently asked questions

Mineral sunscreens use zinc oxide or titanium dioxide, which sit on the surface of the skin. Chemical sunscreens use filters such as avobenzone that absorb into the upper skin layers. Both protect to their labeled SPF. See mineral vs chemical sunscreen.

Not in tested protection — both meet the same FDA standard. Mineral is usually preferred for young children, reactive skin and reef-restricted destinations, and it works immediately on application rather than after 15 to 30 minutes.

About one ounce — a shot glass — for an adult's whole body, and about a quarter teaspoon for face and neck. Most people apply between a quarter and a half of that. See how much sunscreen to apply.

Every two hours, and immediately after swimming, heavy sweating or toweling off. Toweling removes sunscreen mechanically regardless of what the water-resistance claim said.

SPF 30 filters about 97% of UVB and SPF 50 about 98% — or 3% versus 2% transmitted. The stronger argument for SPF 50 is that it buffers against the thin application everybody does. See SPF 30 vs SPF 50.

That the product passed an FDA test showing UVA protection proportional to its SPF. Without the claim, a sunscreen protects against sunburn but not against the UVA linked to photoaging. See what broad spectrum means.

There is no legal definition in the United States. In practice it means zinc oxide or titanium dioxide are the only active filters, with no oxybenzone, octinoxate or octocrylene. See what reef-safe actually means.

Hawaii, Key West, the US Virgin Islands, Palau, Bonaire and Aruba all restrict specific filters. The US Virgin Islands and Palau extend their rules to import and possession. See where reef-safe sunscreen is required.

No. FDA studies found several chemical filters are absorbed into the bloodstream above the threshold that triggers a request for further safety data, which is a data gap rather than evidence of harm. The FDA advises continuing to use sunscreen. See is sunscreen toxic.

The American Academy of Pediatrics advises shade and clothing for infants under six months, with a small amount of mineral sunscreen on exposed skin only when shade is unavailable. From six months, sunscreen is used normally. See sunscreen for babies under six months.

A zinc-only, fragrance-free formula, applied as a stick around the eye area. Stinging is almost always a liquid product migrating with sweat or water. See sunscreen that does not sting eyes.

Zinc oxide and titanium dioxide are white pigments that protect by scattering and absorbing light, including some visible light. The whiteness is the mechanism working. Tinted formulas cancel it optically. See why mineral sunscreen leaves a white cast.

For daily facial wear, usually — the tint removes the cast, and iron oxides add protection against visible light that UV filters do not provide. See tinted vs untinted sunscreen.

After. Moisturizer first, wait about a minute, then sunscreen, then makeup. Applying SPF onto wet moisturizer dilutes it and causes pilling. See where sunscreen goes in your routine.

Yes. FDA rules require sunscreen to hold its stated SPF for three years, and heat shortens that considerably. A bottle that spent a summer in a car should be replaced. See does sunscreen expire.

That the product held its labeled SPF through a specified immersion test. US labels may claim 40 or 80 minutes and nothing else; waterproof was banned in 2012. See water-resistant sunscreen explained.

Only if you apply enough and rub it in, which most people do not. Lotion delivers the tested dose far more reliably, and sprays should never be used near a face. See stick vs lotion vs spray.

Yes. A UPF 50+ garment blocks at least 98% of UV for as long as you wear it, with no reapplication — a higher real-world protection rate than sunscreen achieves for most people. See how UPF clothing works.

Purpose-built UPF synthetics are tested to hold their rating wet. Cotton loses a substantial share of its already-low protection when wet. See does UPF clothing work wet.

Mineral sunscreen is the usual recommendation because zinc and titanium are not meaningfully absorbed, and a tinted one is preferred because melasma is triggered by visible light as well as UV. See sunscreen and pregnancy.

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