The results of sun damage are lasting and can pose harmful threats to your health. At its best, sun damage can cause you to look older than your age; at its worst, it can cause cancerous growths and melanoma. Sunscreen is your best defense in protecting your skin from the sun. The brightly colored tubes and bottles do a good job catching your eye at the store, but the cryptic labels on sunscreen products can leave you more confused than ever. Learn the terminology to decode labels and determine which product is right for you.

Decoding Rays

The sun's rays are ultraviolet (UV) in nature and vary in wavelength. UVA rays are the longest and without protection, your skin will absorb them very easily. UVB rays are shorter than UVA rays, and because the ozone layer absorbs some, your body does not absorb UVB as readily as UVA. Look for UVA and UVB on sunscreen labels before making your purchase. Get the most protection by choosing a "broad spectrum" product--one that protects you against both types of harmful rays.

Understanding SPF

SPF stands for "sun protection factor." The term SPF has been around since the United States Food and Drug Administration (FDA) approved the concept of sunscreen labeling in 1978. SPF measures how much your skin is protected from UVB rays. The higher the SPF number, the longer sunscreen will remain effective on your skin. However, the increase in number doesn't always coincide with increased protection, explains the Minnesota Poison Control System. For example, SPF 15 is on the lower end of the number scale found on sunscreen products, but can block as much as 95 percent of UVB rays from penetrating your skin.

Deceivingly, a sunscreen product with SPF 45 is not three times as good. It provides a longer length of protection time, but almost the same amount of blockage from UVB rays as SPF 15. The easiest way to think about it is to multiply the SPF factor by the length of time it would normally take you to burn without sunscreen. If you burn easily--in 10 minutes unprotected--an SPF 15 will keep you protected for 150 minutes.

The FDA is changing the labeling of sunscreen products in terms of SPF as of 2011. Products that once claimed a SPF higher than 50 (such as SPF 70) will be required to label protection as "SPF 50+." The change is due to a lack of scientific evidence that sunscreen higher than SPF 50 is more effective.

Note: SPF doesn't address the amount of UVA rays that your skin absorbs. People with fair skin are more likely to burn than those with darker skin tones, and should choose a higher SPF number.

Identifying Ingredients

Sun care products are made from chemicals that reduce the ability of UV rays to become absorbed by your skin. Some of the chemicals you may find in the ingredient list of your favorite sunscreen might not be safe, or could irritate your skin. Sunscreen is not recommended for babies under six months.

  • Avoid PABA, or para-aminobenzoic acid, if you have sensitive skin, as this ingredient will likely give you a rash.
  • Oxybenzone is a chemical component in some sun care products that the Health Freedom Alliance advocates against. The Center for Disease Control and Prevention (CDC) identifies it as a toxin that can cause photosensitivity reactions.
  • Octyl methoxycinnamate (OMC) and 4-methylbenzylidene camphor (4-MBC), primarily found in organic sunscreen products, are controversial. OMC and 4-MBC are currently approved for use both in the United States and in the European Union. However, according to studies conducted by the University of Zurich's Institute of Pharmacology & Toxicology, they may interfere with your endocrine system. Discuss use of sunscreens containing OMC or 4-MBC with your doctor if you suffer from endocrine problems.

Applying Sunscreen

No matter which sunscreen you use--a water-based product if you have oily skin, or a yummy-smelling version, for example--best protection is based on proper and consistent use. Follow the "2-2-2 rule:"

  • Use two tablespoons of product (about a shot glass full of lotion)
  • Reapply sunscreen after two hours in the sun (or more frequently if in water or sweating)
  • Throw away all bottles after two years

Apply sunscreen at least 20 minutes before heading outside. Protect yourself with a broad brimmed hat, a lip balm with SPF, and sunglasses and try to avoid the sunniest time of day: between the hours of 10 a.m. and 4 p.m.