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Sunscreens Uncovered

“I used an SPF 85. Why did I burn?”

We hear this every day from our patients. Our patients are confused about sunscreens and we hope you find the following information helpful.

Why do sunscreens fail? There are 4 main reasons why you might burn in the sun despite applying sunscreen:

  • You may not be applying your sunscreen thick enough.
  • You might miss areas of exposed skin.
  • You may not be reapplying your sunscreen every 2-3 hours during sun exposure.
  • Your sunscreen may not meet the minimal FDA standard.



Guidelines for picking a good sunscreen

Look for a sunscreen that meets the following FDA standards:

  • SPF (Sun Protective Factor) of 30 or higher
  • Broad spectrum coverage
  • Water resistant (40 minutes) or Very water resistant (80 minutes).

Do not buy or use a sunscreen that does not have these 3 items on its label

For SPF, it’s not the number that counts. A higher SPF does not mean more protection. SPF reflects the ultraviolet B (UVB) protection a sunscreen delivers. UVB are the rays that cause sunburns. The bottom line is that a sunscreen with an SPF of 30 is more than adequate. You do not get more protection with an SPF 85 sunscreen than with an SPF 30 sunscreen.
This is how SPF works:

  • If you normally burn after being in the sun for 20 minutes, a sunblock with an SPF of 30 will allow you to be in the sun for 30 times that amount (20 minutes x 30 = 600 minutes = 10 hours).
  • Since the effective SPF is half of the labeled SPF, a sunscreen with SPF 30 should protect around 5 hours.

Be sure your sunscreen has broad spectrum coverage. This means that the sunscreen blocks both ultraviolet A (UVA) light and ultraviolet B (UVB) light. The SPF must be at least 30 and the UVA protection must pass a test in which a minimum amount of UVA light is blocked. Unfortunately, no sunscreen is very good at blocking UVA light.

Water resistant is important as well. It should not be labeled “Waterproof,” “sweat proof,” or “all day protection.” Instead, look for labels that say “Water resistant” or “Very water resistant.”


6 steps to protect you and your family in the sun

  • Wear a hat with a wide brim. Baseball caps do not protect your face as well as a wide-brimmed hat and do not protect your ears.
  • Wear UV blocking sunglasses. Avoid applying sunscreen around the eyes–it will sting if you accidently get it in your eyes.
  • Wear a swim shirt or rash guard while in the water. There are many excellent thin, quick drying swim shirts available.
  • Wear a shirt with sleeves while in the sun. “UV protective clothing” is unnecessary, but may be more comfortable than regular clothing in hot weather.
  • Stay in the shade. Do not lay out in the sun and try to get a tan. Bring an umbrella or other shade structure with you when you go to the beach or pool.
  • Apply a “shot glass” amount of sunscreen with FDA approved labelling to exposed areas every 2-3 hours while in the sun. Apply it more frequently if you are in water or swimming.
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