Ask Dr. Louise

What can I do to avoid Sunburn?


Fifteen years ago, on a lovely Saturday morning in Tampa, Florida, I parked my rented Ford Focus next to a baseball field. Patricia, her husband Bill and I had been invited to come watch Frank, a mutual friend’s 10-year old son pitch in a Little League game that afternoon. The weather was perfect: high, wispy clouds, not too humid, with a temperature in the mid-70s.

Frank was warming up in the infield as we claimed 3 seats on the top row of the open bleachers. And 30 minutes later, at exactly 1 pm, the opposing team took the field.

Their pitcher walked the first two boys of Frank’s team, then struck out the next 2 batters. With 2 on base and 2 outs, the pressure was on. The next 2 pitches were balls, then on the third pitch we heard a sharp crack as the ball shot between the first and second basemen, bouncing out to center field before being scooped up. The two runners on base both made it home, and the batter made it all the way to third base. Frank was next at bat, letting two balls go by and valiantly swinging at the next two. With two balls and two strikes, he hit the next pitch, but it was caught by the second baseman, ending the first inning. In the middle of the third inning I felt flushed.  

“Patricia? I feel hot... ”

“Goodness, you’re red as a BEET! You need to get out of the sun RIGHT NOW!”

5 minutes later, I sat in the shade, puzzling over my red, itchy skin. 

“I KNOW I put on sunscreen this morning!”

Exposing our skin to sunshine causes our skin to react by “tanning”, “burning” or even rash and itching. Sunlight contains ultraviolet radiation, which makes exposed skin turn red, creating tanning, burning or other skin reactions like rash and itching. Sunshine has several types of radiation, including ultraviolet A and B. Exposure to ultraviolet B (UVB) radiation causes sunburn, skin cancer and accelerated skin changes such as wrinkles and spots called photo aging.  UVB rays are most intense between 10 in the morning and 4 pm, and help our skin produce Vitamin D.

Like UVB, ultraviolet A (UVA) radiation also causes sunburn and tanning, but in people taking certain medicines it can also trigger redness, swelling and itching in exposed skin, which is called photosensitivity. Normal sunlight has approximately 20 times the UVA radiation as UVB. Because UVB radiation causes more sunburn, 96% of the rays from tanning beds are UVA wavelengths. Back on that day in Florida I was taking a prescription medicine that could cause photosensitivity reactions by increasing increased the sensitivity of your skin to UVA radiation. Unfortunately, the sunscreen I’d applied that morning was several years old and only formulated to protect against UVB rays, not against UVA wavelengths, the ones responsible for photosensitivity skin reactions. Today, most sunscreen products protect against both UVA and UVB radiation.

The measure of how much protection a sunscreen product gives is called its SPF (Sun Protection Factor). The bigger the SPF number, the better the protection. For example, if you properly apply a sunscreen with an SPF of 15, you could stay out in the sun 15 times as long without burning as you could without it. Sunscreens come in two main types: chemical and physical. Chemical sunscreens work by absorbing specific wavelengths of UV radiation before they penetrate your skin, while physical sunscreens reflect and scatter UVA and UVB radiation. The lighter your skin, the more quickly it can burn and the more protection you need.


5 Tips for Avoiding Sunburn or Photosensitivity:


1.  Apply sunscreen at least 15 minutes before you are exposed to the sun. To be most effective, sunscreens need time to bind to your skin.


2.  Don’t skimp when applying sunscreen. The FDA estimates an adult in a swimsuit should use about 4 and 1/2 teaspoonfuls when applying sunscreen to their whole body.


3.  Reapply sunscreen frequently, especially after swimming, playing in the water or just sweating. And don’t forget to reapply sunscreen after drying yourself off with a towel.


4.  Replace your old/expired sunscreen. Although most are good for at least 3 years, when stored near heat they can lose their effectiveness even sooner.


5.  If you take medicine that causes photosensitivity, avoid direct sun or tanning beds. Cover up with long sleeves and a hat with a brim at least 4 inches wide, or apply sunscreen that protects against with both UVA and UVB, reapplying frequently.


Dr. Louise Achey, Doctor of Pharmacy is a 39-year veteran of pharmacology and author of Why Dogs Can’t Eat Chocolate: How Medicines Work and How YOU Can Take Them Safely. Your questions and comments are always welcome at     

© 2018 Louise Achey

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