Forest Dermatology

What You Should Know About Sunscreens

Sunscreens are products that protect the skin from ultraviolet radiation (UVR.)
They do this by using 1) organic chemicals that absorb light and dissipate it as heat such as Avobenzone, 2) inorganic filters or blockers which sit on the surface of the skin and act as a physical barrier to UVR such as Zinc Oxide or Titanium Dioxide or 3) a combination of both.

There are three types of ultraviolet radiation:
UVB: These rays are primarily responsible for sunburn and suntan. Long-term exposure to UVB rays leads to premature aging of the skin and skin cancer.
UVA: These rays are primarily responsible for premature aging and skin cancers such as melanoma and basal cell carcinoma.
UVC: These rays are absorbed by the earth’s atmosphere.

Sunscreens are important in the following ways:
Sunscreens which contain a Sun Protection Factor (SPF) of 30+ filter 97% of UVB rays. However, the SPF rating does not tell you anything about the sunscreen’s ability to protect you from harmful UVA rays. Both UVA and UVB rays are more effectively blocked by sunscreens that contain at least 6% Zinc Oxide, Titanium Dioxide or Avobenzone. A sunscreen may state that it is a “broad-spectrum” product but will not give you adequate protection from UVA rays without adequate filtration.

Sunscreens should all be applied to DRY skin prior to going outside. All sunscreens begin to come off during activity so it is very important to reapply the sunscreen approximately every two hours. No sunscreen provides all-day protection.

"Waterproof” sunscreens have completed only an 80 minute still-water bath test. There are no truly waterproof or sweat proof sunscreens. It is preferable that your sunscreen be “Very Water Resistant.” This means it has sustained its SPF after 240 minutes in moving water. But don’t forget that even “Very Water Resistant” sunscreens require regular reapplication!

Sunscreens with an SPF higher than 30+ don’t necessarily offer better protection from the sun. Remember that the SPF reflects only your degree of protection from UVB rays. Both UVA and UVB rays are blocked by Zinc Oxide, Titanium Dioxide or Avobenzone. Higher SPF sunscreens may provide no more protection from UVA rays and may contain large amounts of organic components which can increase the potential for irritation, especially in children.

The term “sunblock” is a misnomer. No sunscreen blocks ALL sun from the skin. Unless your sunscreen is applied as a thick paste, it will still allow a little UV light to penetrate the skin.


Forest Dermatology
1119 Hendersonville Road
Asheville, NC 28803
828.274.6704
866.744.6003 (toll free)
828.274.6004 (fax)

email: info@forestdermatology.com