How should I use sunscreens?

Most sunscreens have directions on the bottle, which you should read and follow. Choose a sunscreen with a sun protection factor (SPF) of 15 or more. People with fair skin may want to use a product with SPF of 30 to 50. Choose a water-resistant product if you tend to perspire heavily or if you will be in water.

Some sunscreens have ingredients that should be applied one to two hours before you go out in the sun. These ingredients include padimate-O, roxadimate, lisadimate, and aminobenzic acid. Others can be applied one half hour before going in the sun. 

Sunscreens for the lips should usually be applied 45 minutes to one hour before you go out in the sun. Reapply sunscreen every two hours, or more frequently if you are sweating or have been in water. Reapply lip sunscreen at least once per hour, before and after going in water, and after drinking, eating, or other activities that wear off the sunscreen from your lips. Use sunscreen even if the weather is hazy or cloudy, as UV rays can still reach your skin.

Most people do not use enough sunscreen per application. Use the sunscreen liberally on all exposed areas of your skin. Depending on how much of your skin is exposed, you may need a full ounce of sunscreen, which is about a shot glass-full, to thoroughly cover your skin.

Take care to reach these areas that are often missed:
  • scalp exposed by thinning hair or baldness;
  • skin just next to the hairline;
  • nose;
  • ears;
  • back of the neck;
  • lips;
  • and tops of the feet.
Here is how to use sunscreens in order to maximize the protection they offer:
  • Apply sunscreen with a sun protection factor (SPF) of 30 or higher 15 to 30 minutes before sun exposure, with careful attention to sun-exposed areas such as your face, hands and arms.
  • Apply lip balm that contains a sunscreen to protect sun-sensitive lips.
  • Reapply sunscreen at least every two hours. You should apply it more frequently if you have been swimming or sweating. Use about one ounce of cream -- about one shot glass -- to cover your entire body with each application.
  • You should use enough to fill a shot glass each time you apply it. (In fact, consider keeping a shot glass in your beach bag to measure.)
While sunscreen helps to minimize damaging sunburns, it doesn't completely prevent burning. You still should:
  • Try to avoid the sun between 10 a.m. and 4 p.m., when its rays are strongest.
  • Wear a large-brimmed hat and sunglasses to protect your scalp and eyes.
  • Cover other sun-exposed parts of your body.
  • Stay in the shade when possible.
  • Limit the time you spend in the sun.
Use an SPF 30 sunscreen on your face every day, even on days you don't plan to leave the house or office and even on days the sun doesn't shine. That's because you're still exposed to damaging ultraviolet rays through windows and clouds. Thankfully, today it's easy enough to ensure sunscreen coverage. Many moisturizers and even liquid and powder makeup contain sunscreen.
"Ninety percent of wrinkles are from the sun, so sun protection factor (SPF) is the best anti-ager. Everything else is icing on the cake," explains Doris Day, M.D., author of Forget the Facelift. The biggest mistakes people make are not using enough sunscreen and not reapplying their sunscreen. Use enough sunscreen to fill a shot glass, and grease up every 40 to 80 minutes when you're in the sun, says Ellen Marmur, MD, associate professor of dermatology and genetics at Mount Sinai School of Medicine. On days when you're only outdoors before work and on your lunch hour, you still need SPF protection. "I have 90-year-olds with the most perfect skin where the sun never shines, while the sun-exposed skin is mottled, dry, and discolored, so daily causal exposure does add up," says Dr. Marmur. The SPF you apply in the morning will get you to work, but it won't protect you on your lunch hour. For touchups throughout the day, Drs. Marmur and Day recommend SPF mineral powder.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.