What You Need to Know When Buying Sunscreen

Sunscreen may seem like a simple purchase, but choosing the right product can make a world of difference when it comes to protecting your skin. When deciding on what sunscreen to purchase, remember these steps:
Look for both ultraviolet A (UVA) and ultraviolet B (UVB) protection, referred to as “broad spectrum” sunscreen.  While both types of rays can cause sunburn and premature aging, there are some differences.  UVB rays are the burning rays that can cause non-melanoma skin cancer.  However, UVA rays penetrate deeper in the skin and are responsible for subsequent photoaging – course wrinkling and brown spots and overall sun damage. A recent study published in the Annals of Internal Medicine showed that wearing sunscreen daily can reduce photoaging by 24%.  More importantly, studies show that the UVA wavelength is associated with the development of melanoma, the most dangerous form of skin cancer. Tanning booths are comprised primarily of the UVA wavelength which is why it is so important to stay out of them.  Getting in a tanning booth is like getting in a microwave oven.  There is no greater way to cook your skin!
There are two types of sunscreens – physical blocks and chemical sunscreens. Physical sunscreens that contain titanium or zinc oxide provide a physical block of the rays and are not absorbed by the skin.  They work immediately after application.  Chemical sunscreens must be applied 15-20 min prior to going outdoors.  Chemical sunscreens have the potential for absorption.  People with sensitive skin and/or who say that they are “allergic” to sunscreen often cannot tolerate chemical sunscreens, and I would recommend a pure physical block for them.
I always recommended SPF 30 or higher for daily wear to protect against incidental sun exposure. The studies show that over the course of a year, just day-to-day, incidental sun exposure adds up to a one week vacation at the beach. Despite popular belief, SPF 30 is not twice as good as SPF 15 and the number is not the amount of minutes you can spend in the sun. The SPF number refers to the ability of sunscreen to block out UVB rays. It does not give any indication of UVA protection.  For outdoor sports or activity, I recommend 50 or greater.  There is an incremental increase difference in SPF protection the higher you go.
SPF 15- filters 93% of UVB rays
SPF 30- filters 97% of UVB rays
SPF 50 – filters 98% of UVB rays
The FDA released new regulations in June 2012 on sunscreen guidelines.  Because there is no such thing as a truly ‘waterproof” sunscreen, sunscreen manufacturers must comply with the following guidelines:
Water resistance claims on the product’s front label must tell how much time a user can expect to get the declared SPF level of protection while swimming or sweating, based on standard testing.  Only two times will be permitted on labels: 40 minutes or 80 minutes.
Manufacturers cannot make claims that sunscreens are “waterproof” or “sweatproof” or identify their products as “sunblocks.”   Also, sunscreens cannot claim protection immediately on application (for example, “instant protection”) or protection for more than two hours without reapplication, unless they submit data and get approval from FDA.
Pay attention to the consistency of sunscreen that you choose: foam, lotion, or aerosol. I recommend an aerosol spray to maximize surface area coverage for the body.  Be sure to have an even and consistent application. Regardless of what SPF you choose or what consistency, make sure you reapply every two hours for outdoor activity.
The most important step (and most common mistake) is to make sure you apply enough product for adequate coverage.  The general rule of thumb is that it takes about a shot glass full to cover the entire body.  If you use half the required amount, then the effective protection will be about half the labeled SPF.
What brand? This is up to you!  You don’t have to spend a lot of money to find a good sunscreen.  It’s a matter of personal preference and also usually depends on the body location.  Your dermatologist can suggest a brand that it right for you.
Mary Hurley, MD

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North Dallas Dermatology Associates8144 Walnut Hill Lane Suite 1300
Dallas Texas 75231
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