How does zinc oxide work?

Does zinc oxide just reflect sunlight?

No. Mineral sunscreens absorb UV rays as well as reflecting them. Chemical sunscreens also form a protective layer that absorbs UV rays. A sunscreen containing only zinc oxide, titanium dioxide or both as its active ingredients is called mineral or physical sunscreen. A hybrid sunscreen combines mineral filters with other sunscreen filters. Check the Active Ingredients section to identify the type.1

What should you look for in a zinc oxide sunscreen?

Choose broad spectrum protection, SPF 30 or higher and water resistance. Broad spectrum means protection against both UVA and UVB rays; SPF tells you about sunburn protection. A sunscreen label needs both an SPF number and broad spectrum wording, because one number cannot do all the paperwork. Zinc oxide on the ingredient list is not a substitute for checking the finished product's protection claims.13

How do you use zinc oxide sunscreen?

1. 1Apply sunscreen 15 minutes before sun exposure, following the product's directions.
2. 2Cover all exposed skin evenly, avoiding the eyes and mouth. An average sized adult needs at least one ounce to cover the body from head to toe.
3. 3Include easily missed areas such as the ears, back of the neck, hands, tops of the feet, hairline and exposed scalp. Use SPF lip balm on the lips.
4. 4Reapply at least every two hours outdoors and after toweling off. During swimming or sweating, follow the label's water resistance limit of 40 or 80 minutes.

No sunscreen is waterproof or filters out every UVB ray. Use shade and protective clothing alongside sunscreen, and limit time in strong midday sun. SPF is not a measure of how many extra hours you can safely stay outdoors.13

Does zinc oxide suit sensitive skin?

Dermatologists recommend mineral sunscreen for sensitive skin. For children aged six months and older, zinc oxide or titanium dioxide sunscreens are less likely to irritate sensitive skin. For babies younger than six months, prioritize shade and protective clothing, and ask a doctor before using sunscreen.13

Tinted sunscreen can help avoid the white cast left by some sunscreens, so protection does not have to announce itself in white. Tinted formulas containing iron oxide also help protect against visible light, which contributes to dark spots and melasma, a condition that causes patches of darker skin.1

Is a zinc oxide ointment also sunscreen?

Zinc oxide is used in pastes, ointments and bandages as well as sunscreens. For sun protection, choose a product labeled as sunscreen with an SPF and broad spectrum protection rather than treating any zinc oxide preparation as interchangeable. Follow the directions for the product's intended use.23