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Health Library : Skin Cancer



Picture of two young girls giggling by the side of the pool

What are sunscreens?

Sunscreens protect the skin against sunburns. Sunscreens also play an important role in blocking the penetration of ultraviolet (UV) radiation, which damages the skin and can lead to skin cancer. However, no sunscreen blocks UV radiation 100 percent.

What is the difference between a sunscreen and a sunblock?

The terminology used on sunscreen labels can be confusing. The protection provided by a sunscreen is indicated by the sun protection factor (SPF) listed on the product label. A sunblock is considered to be any sunscreen with an SPF of 15 or more. In theory, sunscreens protect an individual during ultraviolet B (UVB) radiation exposure according to the following:

  • SPF 15 sunscreen may absorb 93 percent of UVB radiation.
  • SPF 30 sunscreen may absorb 97 percent of UVB radiation.
  • SPF 2 - 4 sunscreen may absorb 50% of UV radiation and offers the least protection

How to select a sunscreen

A sunscreen protects from sunburn and minimizes suntan by reflecting UV rays. Selecting a good sunscreen is important in protecting the skin. Consider the following information:

  • A sunscreen with SPF of 20 to 30 offers substantial protection against sunburns, and usually prevents tanning.
  • A product that has "broad spectrum" on its label means the sunscreen filters out ultraviolet A (UVA) and ultraviolet B (UVB) radiation exposure.
  • The American Academy of Pediatrics (AAP) recommends the selection of sunscreens with the new UVA "star" rating system on the label. In this system, one star means low protection; two is medium protection; three provides high protection; and four offers the highest UVA protection available in over-the-counter sunscreens.
  • Sunscreens are recommended for everyone over 6 months of age, regardless of skin or complexion type, because all skin types need protection from solar UV rays. (For babies younger that 6 months, check with your health care provider.) For babies over 6 months of age, apply sunscreen to all exposed areas of the body, but be very careful around the baby's eyes. If your baby develops a rash after you use sunscreen, check with your doctor. Remember - a baby's best defense against sunburn is staying in the shade or avoiding the sun.
  • Lighter skin types are at the greatest risk of developing skin cancer; but all people are at some risk. Research has shown that UVA rays may contribute to premature aging and skin cancer.

How to apply a sunscreen

  • Apply sunscreen to all exposed areas of skin, including those easily overlooked areas such as the rims of the ears, lips, back of the neck, and feet. For these sensitive areas, the AAP suggests sunscreens with zinc oxide or titanium dioxide.
  • Apply sunscreen liberally and rub it in well. The recommended dose is one ounce per application.
  • Apply the sunscreen 30 minutes before going outdoors - it needs time to absorb into the skin.
  • Remember - you can burn from UV rays that bounce back from water, snow, concrete, and sand. Apply sunscreen any time you may be at risk for a sunburn.
  • Reapply every two hours, after being in the water, or after exercising or sweating. Incidental time in the sun could add up to a sunburn. Do not forget the time spent walking your dog, window shopping, performing outdoor chores, or jogging on your lunch hour.

Click here to view the
Online Resources of Skin Cancer

 Sources & References


 Find an MUSC Doctor:
 »Dermatologic Surgery



 Interactive Tools:
 »Skin Cancer Quiz

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