Q&A: Sunscreen vs Sun Block

Woman shopping for sunscreenQ: Is there a difference between sunscreen and sun block?

A: As summer approaches, we stock up on sun-protective gear. A walk down the “seasonal” aisle at your local store can be dizzying. Which product to choose – a sunscreen or sun block? Is there a difference, or are they interchangeable? 

There are, in fact, somewhat “technical” differences between the two. Sunscreens, also known as chemical blockers, are absorbed into the skin, so they should be applied 10–15 minutes prior to going out in the sun. Sunscreens absorb ultraviolet (UV) light in certain wavelengths. The UVA rays can cause long-term effects and contribute to photoaging and wrinkles. UVB rays are responsible for short-term effects like sunburns. UV light can easily degrade sunscreen, so it’s crucial to reapply every few hours for maximum effectiveness. Avobenzone, oxybenzone, and Mexoryl™ are common ingredients in many chemical blockers these days.

In contrast, sun blocks, also known as physical blockers, primarily sit on top of the skin and reflect the sun’s UV rays prior to its penetration into the skin. The earliest physical blockers included zinc oxide or titanium dioxide (think of the white paste on a lifeguard’s nose). Today’s formulations are micronized, allowing more even coating and a lighter feel on the skin. Because sun blocks do not absorb into the skin, they are an ideal choice to use on children and infants aged older than 6 months. Many products on the market do contain both physical and chemical blockers.
So which product should you buy? In short, it depends on the person using it. Some people are sensitive to ingredients in chemical blockers or sunscreens, developing allergic contact dermatitis, or an itchy rash. If you or your family members are sensitive to blocker or sunscreen products, closely read the label on your product of choice. The most important choice is to use some type of sun-protection measure every day…and remember to reapply!

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Published on 06/08/2009 | Last updated on 10/18/2018