How to Choose and Use Sunscreen for Optimal Protection

May is Skin Cancer Awareness Month and an ideal opportunity to make your summer sun protection plan. More than 5 million Americans are diagnosed with skin cancer every year, even though it’s one of the most preventable cancers.

Prevention starts with choosing and properly using an effective sunscreen. In this month’s blog, Board-Certified Dermatologist Patrick Keehan, DO, and Morgan Magnuson, PA-C, of Keehan Dermatology, explain how to do just that.

First, let’s start with a quick recap about how the sun's damaging rays can prematurely age your skin and cause cancer. 

The ABCs of UVA and UVB rays

Both UVA and UVB rays have the potential to harm your skin. UVA rays, which make up approximately 95% of the UV radiation that reaches the Earth's surface, penetrate deep into the skin, accelerating the aging process of skin cells. UVB rays, which comprise the remaining 5%, primarily affect the skin's surface, leading to sunburn. These rays directly harm the outer layers of the skin.

Always choose a sunscreen that provides UVA and UVB protection. Go for a zinc oxide or titanium dioxide product, which helps block both harmful rays. Instead of a numerical rating, UVA-ray protection is designated by the term broad spectrum. A broad spectrum’s UVA protection level will be roughly proportional to its UVB protection level (SPF rating).

Understanding SPF ratings

SPF indicates how much longer you can stay in the sun with sunscreen than without it. But SPF numbers can be misleading. For instance, SPF 30 isn't twice as effective as SPF 15; it's just slightly better. Anything over SPF 50 offers a little extra protection. Stick to SPF 30 or higher for simplicity.

Sunblock vs sunscreen 

Sunblock provides a physical defense that uses minerals to absorb UV rays and starts working as soon as you put it on. Sunscreen is a chemical formula that works by absorbing into the skin. It must be applied at least 15 minutes before sun exposure for ample time to sink in. The SPF number does not vary between sunblock and sunscreen, which is the sun protection factor (SPF).  Sunblock or sunscreen is equally effective if you apply them correctly.

Choosing the right sunscreen

The Keehan Dermatology team’s top choice is any of EltaMD’s suncare products, available at our office. EltaMD is a pharmaceutical-grade sun care line. Pharmaceutical-grade skincare products contain 99.9% pure active ingredients and are backed by scientific research. 

Over-the-counter skincare products purchased at the drug store or department store contain only 70% pure ingredients, per FDA requirements. Unlike pharmaceutical-grade products, OTC brands also contain inactive compounds, fragrances, and preservatives. 

How to apply sunscreen

Begin by evenly applying a generous amount of sunscreen over all exposed skin areas. A good guideline is to use approximately one ounce of sunscreen, equivalent to a shot glass full, to cover your entire body. Use about a nickel-sized amount for your face, spreading it across the forehead, nose, cheeks, and chin.

Apply sunscreen after your moisturizer and before applying your makeup.

Don’t miss those often forgotten spots, including:

• Neck
• Wars
• Hands
• Tops of your feet 
• Along the hairline
• Scalp (if you have thinning hair)

How and how much sunscreen to use?

Apply sunscreen 15 minutes before going out in the sun. Most adults need around 1 ounce, roughly the amount that fills a shot glass, to cover their whole body. Fair-skinned individuals absorb more sunlight compared to those with darker skin tones. But regardless of skin type, everyone should apply sunscreen generously, ensuring it's well-rubbed into all exposed areas. Remember to ask for help with applying sunscreen to your back. And remember to protect your lips with lip balm containing at least SPF 15.

When to reapply?

Remember to reapply sunscreen every two hours, no matter its SPF.

If a sunscreen is labeled as "water-resistant," it's designed to remain effective even when in contact with water or sweat. However, keep in mind that no sunscreen is completely waterproof or sweatproof, as per FDA regulations.

They have a specific test, though, and you should find one of two ratings:

• water-resistant for 40 minutes
• water-resistant for 80 minutes.

Remember, too, that toweling off your skin removes sunscreen. So, constantly reapply sunscreen immediately after using a towel.

Book an appointment at Keehan Dermatology in Fort Worth, Texas, for more information about protecting your skin this summer, an annual skin check, and all your skincare needs. Call the office at (817) 769-3603 or reach out online.