What is it? Approved by the Food and Drug Administration for sunscreen use, zinc oxide is the safest and most effective ingredient for protecting against long-wave UVA rays, which deeply penetrate the skin and cause elastic tissue damage and photoaging. What’s more, UVA rays weaken the immune system and increase the risk of skin cancer such as melanoma.

UVB rays primarily affect the skin’s top-most layer and harm skin cell DNA by eliciting the formation of oncogenes, which are genes that can turn normal cells into malignant ones, leading to basal cell and squamous cell cancers.

For protection against both long-wave UVA and UVB radiation as well as against short-wave UVA radiation - which can also lead to skin cancer — zinc oxide is the sunscreen ingredient you want. In fact, it’s the only one that will protect you against all three.

You'll find it in: Zinc oxide is found in a wide variety of creams, ointments, lotions and sprays as transparent zinc oxide. Also, because zinc oxide can be formulated for sensitive skin and has antifungal and antimicrobial properties, it's used in antiseptic ointments that treat minor skin irritations such as burns, cuts, poison ivy and diaper rash.

Our product picks: To make sure that the product you choose provides enough protection from the sun, you should shoot for one comprised of at least 5 percent zinc oxide. One such sunscreen is SkinCeuticals Daily Sun Defense SPF 20, which moisturizes your skin, making it perfect for daily use. Another great option is Obagi Nu-Derm Physical UV Sun Block SPF 32, which contains 18.5 percent zinc oxide and is also gentle enough for daily use.

You'll also find zinc oxide in soothing skincare products that calm red and blotchy skin, such as Pevonia Soothing Sensitive Skin Mask.

What to expect: When used properly, zinc oxide is very well-tolerated. In fact, there have been no reports of any side effects, but that doesn't mean it isn't possible. If you experience anything unusual, notify your doctor immediately.

When using products with zinc oxide, optimally, you can avoid skin cancer. And as if that wasn't enough, scientists believe that 90% of wrinkles, roughness, skin tone loss, discolored skin and other signs of aging result from UV damage, so zinc oxide prevents against photodamage and premature aging. You can expect convenience with zinc oxide products as well; those made for daily use are typically non-greasy and can be worn under makeup, so you don't have to worry about changing your skincare regimen.

Who should avoid it: If you're pregnant or nursing, talk to your doctor before using any product containing zinc oxide. Also make sure your doctor says zinc oxide is appropriate to use if you're allergic to latex, react unusually to medicines, foods, dyes or preservatives.

See also:

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A Brief History of Beauty

Does Mineral Makeup Provide Enough Sun Protection?