How should I apply sunscreen?

Sunscreen needs to be applied correctly to achieve that maximum sun protection advertised on the sunscreen bottle.  Below are some tips for getting the most out of your sunscreen:

• Sunscreen should be applied 15-30 minutes prior to sun exposure and sweating to allow it to dry and absorb into the skin. 
• Each adult should use about 1 ounce of sunscreen when covering the whole body.  The thicker you apply the sunscreen, the more likely you are getting the advertised SPF on the sunscreen bottle.  Since most of us apply sunscreen in much thinner amounts than have been clinically tested, we are probably getting less than half the SPF advertised on the sunscreen bottle.   If in doubt, use sunscreens with an SPF of at least 30 and apply generously. 
• Once applied correctly, you must reapply sunscreen every 2 hours to maintain maximum protection. 
• If you anticipate swimming or sweating, use a water resistant sunscreen and reapply as indicated.  There are two phrases that the FDA has clearly defined for advertising on sunscreen labels:  “water resistant” and “very water resistant.”  If the bottle says “water resistant,” you must reapply sunscreen every 40 minutes while sweating to maintain adequate protection.  If the bottle says “very water resistant,” you must reapply every 80 minutes.  Unfortunately, the phrase “waterproof” is not an FDA defined phrase for sunscreen, but likely you can assume 40 minutes of protection with sweating or swimming before reapplication is necessary for “waterproof” sunscreens.
• When applying to children, sunscreen sticks may give you more control to avoid application in the eyes.
• In addition to sunscreen, consider other sun protective measures to protect your skin.  These include sun protective clothing, broad rimmed hats, and sun avoidance by planning activities in the early morning, late afternoon or evening. 

It is important to apply sunscreen half an hour before you will be in the sun. Also, make sure you reapply after you get out of the water and reapply every one to two hours. Sunscreen should be applied evenly and thickly to any sun-exposed areas.

The best technique for an even application of sunscreen is to dab it on in little dots all over one area (such as your face, neck, and ears). Once your dots are in place, rub them in and move on to the next area. This way you can see exactly where you have applied the lotion, so you don't miss any spots. Apply it mindfully and thoroughly from head to toe, or vice versa, so you don't forget any areas. If you skip around, it's too easy to forget where you've applied or not, in case you're interrupted (the phone rings, one of your kids needs you, the toast is burning, anything!).

To be effective, chemical sunscreens need to be rubbed into the skin 20 minutes before sun exposure. They do a pretty good job at blocking UV light, but they actually get used up as the sun shines on them. In fact, some sunscreens lose as much as 90% of their effectiveness in just an hour, so they need to be reapplied often.