American Family Children's Hospital

What You Should Know About SPF

Boy applying sunscreen; Tips for staying safe in the sun
Sunscreens with sun-protection factors (SPF) of 100 or more may not provide the bullet-proof protection you might expect.


Current sunscreen manufacturers are required only to label products for the amount of UVB protection they provide.


UVB is ultraviolet (UV) light which commonly causes sun tanning and burns.


Both UVA and UVB cause skin aging and can lead to skin cancer. Newer products do offer "broad spectrum" protection with better UVA blocking, but they still remain less effective compared to how they block UVB.


But SPF is only part of the story. You should consider the following when determining the most appropriate sunscreen for your situation:

  • Your skin type
  • What type of sunscreen is appropriate for your skin
  • The clothes you'll be wearing
  • Whether there is a family history of sun damage and skin cancer
  • Whether you're taking medications that may make you light-sensitive

And it's important not to get a false sense of security by using products labeled "waterproof," as no products are truly waterproof. Instead, sunbathers and swimmers should reapply sunscreen regardless of the company's use directions.


The best products are those with zinc oxide or titanium dioxide, and those with protection from both UVB and UVA.


Skin Cancer Q and A
A UW Health dermatologist and Mohs micrographic surgeon offers some sensible tips to help prevent sunshine from causing serious health problems.