Summer is here and so is the sun – here is your guide to sunscreen this summer. From what you want to know about SPF to UVA vs UVB vs Broad Spectrum, to the effectiveness of spray screens, Vitamin D absorption with sunscreen and much much more.

The Ultimate Guide To Sunscreen

What Is SPF?

Starting with the basics: SPF stands for Sun Protection Factor. The Sun Protection Factor (SPF) displayed on the sunscreen label ranges from 2 to as high as 50 and refers to the product’s ability to screen or block out the sun’s harmful rays. For example, if you use a sunscreen with an SPF 15, you can be in the sun 15 times longer that you can without sunscreen before your skin starts to burn. For the average person, skin begins to burn after about ten minutes in the sun. Something that you need to be aware of: SPF protection does not increase proportionally with an increased SPF number. For example, an SPF of 2 will absorb 50% of ultraviolet radiation, an SPF of 15 absorbs 93% and an SPF of 34 absorbs 97%.

What Types Of Sunscreen Are There?

There are a few different sunscreen protections out there. Some types of sunscreen block only ultraviolet-a (UVA) rays from the son, while others block ultraviolet-b rays (UVB). Others block both. It’s important to check the label of your sunscreen to see which types of rays the sunscreen will protect against. In more recent years, most products protect against both types of ultraviolet rays. As a general rule of thumb, children’s products protect against both types.

UVA Sunscreens

UVA sun rays can prematurely age your skin. It causes wrinckles, age spots, and UVA rays can pass through window glass. UVB rays are the primary cause of sunburn and are blocked by window glass. Some sunscreens only protect against UVA sun rays.

Broad Spectrum Sunscreen

Broad spectrum sunscreens are sunscreens that protect against both UVA and UVB rays and should be the only type of sunscreen you purchase.

Things To Look Out For

Skin Cancer and/or Skin Aging Alert

If your sunscreen has a Skin Cancer or Skin Aging Alert in the Drug Facts section of the label, that means your sunscreen does not block against both UVA and UVB. This also applies to broad spectrum sunscreens that are between 2-14 SPF. Translation: buy stronger sunscreen.

Spray Sunscreens

FDA regulations on sunscreen testing and standardization do not apply to sunscreen sprays. I know many people think that sprays are easier to apply but the standards for sprays just aren’t the same. People usually don’t apply as much with a spray as they do compared to bottled products as well.

Can Using Sunscreen Limit Vitamin D Absorption?

The simple answer: yes. The best way to effectively get Vitamin D so your body can use it the best is from the sun. The good thing is: all you need is about ten to fifteen minutes of sun for lighter colored skin to get your daily needs of Vitamin D. However, any sunscreen or sunblock will decrease the absorption of vitamin D.

How Often Should You Reapply?

The American Academy of Dermatology recommends that sunscreen application should take place every two hours or if the label says differently, whatever it says on the label. Also reapply after swimming or excessive sweating. It’s also recommended that every application should be enough sunscreen to fill a shot glass and to apply the sunscreen fifteen minutes before going outdoors.

Difference Between Sunblock and Sunscreen

A lot of times the terms for sunscreens and sunblocks will be used interchangeably but there is a difference. Sunscreens are put into two different types: chemical or physical. Chemical sunscreens make special ingredients that act as filters and reduce the ultraviolet rays that penetrate the skin. These chemical sunscreens are usually colorless when applied to the skin and usually only contain UVB absorbing chemicals – again, it’s important to check the label to find out if both UVA and UVB are protected against.

Physical sunscreens are referred to as sunblocks and contain ingredients that provide a physical barrier to block ultraviolet radiation from the sun. The most common ingredients are titanium dioxide or zinc oxide. These products provide broad spectrum protection from the sun. These sunblocks are usually what you think of when you see a white strip on someone’s nose or face. I actually prefer these products and most dermatologists would recommend these products over a sunscreen. Products containing zinc oxide have stood the test of time when it comes to effectiveness. When I spend several hours in the sun surfing, zinc oxide is my go to.


1. N.a. “Facts About Sunscreen.” American Melanoma Foundation. 2006. Web. 30 June 2015.
2, N.a. “Sunscreen FAQs.” American Academy of Dermatology. 2015. Web. 30 June 2015.