In my last article, I discussed the type of sunscreen that we need to use, (i.e. the kind that has both UVA and UVB protection). I also discussed the meaning of SPF ratings. I promised you that I will inform you how much sunscreen to apply, how often, and what’s the best formulation to use.
Unknown to many, there is a dosing guide for sunscreens. Sadly, most sunscreen bottles do not have that written down. Several studies have shown that most people actually apply less than the recommended dose, putting them at risk for sun damage.
What is the recommended dose of sunscreen?
It’s 2mg/cm2 of skin. Say that again? For practical purposes, doctors have devised a way to divide different areas of the body to 11 sections. Each section will need two (2) “fingertip units” of sunscreen for adequate coverage.
The fingertip unit is the “strip of cream squeezed out of the tube onto the fingertip, from the distal crease of the index finger to the end of the finger itself”. The different sections of the body that require 2 fingertip units each, if exposed, are: (1) head, neck & face; (2) left arm; (3) right arm; (4) upper back; (5) lower back; (6) upper front torso; (7) lower front torso; (8) left upper leg/thigh; (9) right upper leg/thigh; (10) left lower leg/foot; (11) right lower leg/foot.
The fingertip measure will be based on the finger of the person who will wear the sunscreen such that the amount of product to be used is in proportion to ones body size. For example, if a toddler is going to use the sunscreen, then the fingertip measure will be based on the toddler’s fingertip. If you think that it is too much, liken it to 2 coats of paint – which is how much you usually need to make the surface irregularities like fine lines and wrinkles disappear!
Adequate coverage is key. Lotions or creams are spreadable and can easily cover exposed skin. Creams are often used for the face. Sticks are good to use around the eye area, and there are lipsticks with sun protection too. Spray sunscreens tend to miss a spot, especially if there is a gust of wind while you are spraying the product. Avoid inhaling it. Spray sunscreens may be convenient for balding scalp. Gels are good for hairy areas.
Apply sunscreen 15 minutes before going outdoors. Then re-apply as needed, that is, every two hours when you are outdoors, or right after swimming or sweating heavily.
Do not be fooled by overcast skies. Clouds cannot effectively block the harmful UV rays. Take extra precaution when you are in the water, sand or snow, as these elements reflect the rays of the sun. In addition to sunscreens, wear tightly woven clothing, hats, and use your umbrellas or parasol. If your shadow is shorter than you, it is time to seek shade!
Written by: Dr. Isay. She is a graduate of UP College of Medicine and had her residency training in Dermatology at the same institution.
Steve Taylor and Brian L.Diffey. Has the sun protection factor had its day? BMJ.
American Academy of Dermatology. Sunscreen FAQs.