Sun Protection and Sunscreens

  • Medical Author:
    Melissa Conrad Stöppler, MD

    Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

  • Medical Editor: William C. Shiel Jr., MD, FACP, FACR
    William C. Shiel Jr., MD, FACP, FACR

    William C. Shiel Jr., MD, FACP, FACR

    Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

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What is sun protection?

Sun protection is simply guarding a body from the adverse effects of sunlight. Aside from the hazards of heat, the sun poses the danger of sunburn, which can permanently damage the skin and cause skin cancer, precancerous changes in the skin, as well as premature wrinkling and signs of aging. Exposure to ultraviolet rays from the sun is a known risk factor for the development of both melanoma and nonmelanoma skin cancers. A survey conducted by the U.S. Centers for Disease Control and Prevention (CDC) and published in 2015 showed that despite public health warnings, only around one-third of Americans use sunscreen on a regular basis. Women were more likely than men to use sunscreen on the face, and sunscreen use was also more common in higher socioeconomic groups.

What are the best ways to prevent a sunburn?

The best ways to avoid sunburn are to do the following:

  • Limit time in the sun, especially between the peak sunlight hours of 10 a.m. and 3 p.m.
  • Wear protective clothing, including
    • a broad-brimmed hat,
    • a shirt with sleeves that cover the arms, and
    • a long skirt or pants with long legs.
  • Use a protective sunscreen to minimize the penetration of the sun's ultraviolet (UV) rays.
  • Use a water-resistant sunscreen if swimming or perspiring heavily.

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Find out how to choose the best sunscreen.

Making Sense of Sunscreen Products

SPF stands for sun protection factor. The SPF numbers on a product can range from as low as 2 to as high as 60. These numbers refer to the product's ability to screen or block out the sun's burning rays.

Picture of a sunburn

What is sunscreen?

Sunscreen is any substance or material that protects the skin from UV radiation. Sunscreens are available in the forms of topical lotion, cream, ointment, gel, or spray that can be applied to the skin; a salve or stick that can be applied to the lips, nose, and eyelids; a moistener in towelettes that can be rubbed against the skin; sunglasses that protect the eyes; certain types of sun-protection clothing; and film screen that can be affixed to the windows of a car, room, or office. Many facial moisturizers and cosmetics products also offer some degree of sun protection.

What is meant by SPF?

SPF, an abbreviation for sun-protection factor, is a number such as 15, 30, or 50 that indicates the degree of sunburn protection provided by sunscreens. SPF is related to the total amount of sun exposure rather than simply the length of sun exposure. It is a common mistake to assume that the duration of effectiveness of a sunscreen can be calculated simply by multiplying the SPF by the length of time it takes for him or her to suffer a burn without sunscreen, because the amount of sun exposure a person receives is dependent upon more than just the length of time spent in the sun. The amount of sun exposure depends upon a number of factors, including the length of exposure, time of day, geographic location, season, and weather conditions.

A common mistake is applying too little sunscreen, which can drastically reduce the effective SPF of the product. About 1 ounce (5-6 teaspoons) of sunscreen is recommended to cover the entire body. Further, sunscreen must be reapplied every two hours when staying outdoors for a prolonged period of time. Sunscreen should also be applied at least 30 minutes before going outdoors.

People with sensitive skin who burn quickly and must spend a lot of time outdoors should always apply a broad-spectrum sunscreen with an SPF of 30 or more. The U.S. FDA has also recommended that the maximum SPF value on sunscreen labels be "50+" because many scientists believe that there is insufficient evidence to show that products with SPF values higher than 50 provide greater protection for users than products with SPF values of 50.

A major limitation of the SPF value is that these numbers are determined from a test that measures protection against sunburn caused by ultraviolet B (UVB) radiation. Therefore, SPF values only indicate a sunscreen's UVB protection and do not provide any information on the product's effectiveness in blocking the ultraviolet A (UVA) rays that contribute to the development of skin cancers. Rulings issued in 2011 require more accurate labeling of sunscreen products than was required in the past.

Are all sunscreens equally effective against UV radiation?

No. Some sunscreens protect against only one type of ultraviolet radiation: ultraviolet-B (UVB). Others protect against both types of ultraviolet radiation that reach earth's atmosphere from the sun: ultraviolet-B and ultraviolet-A (UVA). UVB rays account for only 5% of the UV rays reaching the surface of the earth. UVB rays cause sunburn and contribute to aging of skin, skin cancers, and hyperpigmentation. The majority (about 95%) of UV rays that reach earth are UVA rays. While these are less potent than UVB rays, they are also thought to promote skin cancers and skin aging.

Sunscreens that protect against both UVA and UVB, and are thus classified as "broad spectrum," are recommended for everyone. There are new regulations in labeling of sunscreen products that allow consumers to better understand the degree of protection offered by a given product.

How do sunscreens work, and which sunscreen ingredients protect against both types of UV radiation?

Physical sunscreens containing zinc oxide or titanium dioxide protect against UVB and UVA. However, zinc oxide blocks more UV radiation than titanium dioxide and, therefore, is the preferred ingredient. Some chemical sunscreens can also block UVA rays. Octocrylene is a chemical known as a cinnamate that has both UVA- and UVB-absorbing properties, and the benzophenones (such as avobenzone) can also absorb both UVA and UVB rays. In July 2006, the U.S. FDA approved an over-the-counter (OTC) sunscreen preparation known as Anthelios SX that contains the UVA filter ecamsule. Ecamsule is a potent UVA-blocking compound that has been sold in sunscreen products in Canada and Europe since 1993. Because in the U.S., sunscreens are regulated by the FDA as are drugs, it is typically more difficult to gain approval for newer sunscreen products than in countries where sunscreens are legally cosmetics products.

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How should skin sunscreens be applied?

It's a good general rule to apply a sunscreen very liberally. Those who skimp won't receive full protection. Most people do not use enough sunscreen and do not apply frequently enough. The sunscreen should be applied about a half hour before going outside to allow time for the sunscreen to soak in and take effect. If you're not sure, it's better to over-apply than to apply too little. There is no damage or danger associated with using too much sunscreen.

Many women use foundation makeup that contains sunscreen. However, this should be used as an extra layer of protection rather than the only source of sunscreen, because the amount of makeup that is needed usually is far below the amount that would be needed for effective sun protection.

Applying sunscreen only on sunny days or when it is hot is a common mistake. While the sun may be stronger in summer, UV rays can penetrate clouds and fog and can cause damage even when the sun isn't bright.

Do water or perspiration wash off sunscreen? How long does sunscreen last?

Yes, water and perspiration can wash off sunscreen. Sunscreens must be reapplied frequently. Therefore, sunscreen should be reapplied at least every two hours when staying outdoors for a prolonged period and after swimming, bathing, perspiring heavily, or drying off with a towel or handkerchief. Water- and perspiration-resistant sunscreens are available. However, even their protection will not last indefinitely, and they should be reapplied frequently, as well.

Can sunscreens cause a skin reaction?

PABA (para-aminobenzoic acid) was one of the original UVB-blocking products in sunscreens. Some people developed a skin reaction to this chemical, and it was also found to stain clothing. Over the years, PABA has been refined and modified into newer ingredients known as glycerol PABA, padimate A, and padimate O, all of which are UVB-blocking sunscreen ingredients. Other ingredients in sunscreens may also increase the risk of a skin reaction in certain people. Anyone can determine the suitability of a particular sunscreen without risk of serious harm by

  1. clothing his or her body fully except for a small patch of skin; and then
  2. applying the sunscreen to the skin patch and exposing it to sunlight.
  3. If a reaction occurs, the user should not use that product. He or she should try another product.

Should everyone use sunscreen protection?

As a general rule, babies 6 months of age or younger should not have sunscreen applied to their skin because their bodies may not be capable of tolerating the chemicals in sunscreens. Instead, they should be kept away from sun exposure.

Everyone over 6 months of age should use a sunscreen regularly unless they and their doctors decide it would be better to protect the skin in other ways. Even with sunscreen use, wearing protective clothing and eyewear to shield UV rays are recommended. Sunscreen alone should not be regarded as complete protection from all UV radiation.

Can the labels on sunscreen products be trusted in the U.S.?

In the past, manufacturers' claims on sunscreen packaging were largely unregulated. However, in 2011, the U.S. Food and Drug Administration (FDA) issued labeling regulations for over-the-counter sunscreens. According to these FDA guidelines, sunscreen labels were prohibited from making claims that are considered unproven or absolute such as "waterproof" and "all-day protection." Earlier regulations for sunscreens concerned protection against sunburn, which is primarily caused by ultraviolet B (UVB) radiation from the sun, and did not address ultraviolet A (UVA) radiation, which is a cause of skin cancers and early skin aging.

According to the FDA ruling, all products that claim to provide broad-spectrum sun protection must comply with the following rules:

  1. If a sunscreen is labeled as "broad spectrum," it must pass a test that measures the product's ultraviolet A (UVA) protection relative to its ultraviolet B (UVB) protection. The label must indicate the degree of SPF or overall protection. Broad-spectrum SPF products with SPF values higher than 15 provide greater protection and may claim additional uses, as described below.
  2. Manufacturers of broad-spectrum sunscreens with SPF of 15 or higher may claim that these products reduce the risk of skin cancer and early skin aging if used as directed with other sun-protection measures. Non-broad-spectrum sunscreens (those that do not pass the broad spectrum test described above) and broad-spectrum sunscreens with an SPF value between 2 and 14 can only claim to help prevent sunburn.
  3. Manufacturers cannot label sunscreens as "waterproof" or "sweatproof" or identify their products as "sunblocks" because these claims are exaggerations. No sunscreen can completely block the sun's rays. According to the FDA ruling, "Sunscreens also cannot claim to provide sun protection for more than two hours without reapplication or to provide protection immediately after application (for example, instant protection) without submitting data to support these claims and obtaining FDA approval."
  4. Manufacturers of sunscreens that claim to be water resistant must indicate on the product label whether the sunscreen remains effective for 40 minutes ("water resistant") or 80 minutes (labeled "very water resistant") while swimming or sweating, based on standard testing. Products that are not water resistant must contain instructions on the label telling consumers to use a water-resistant sunscreen if swimming or sweating.

The Environmental Working Group, in a 2015 study of over 1,700 sun-protection products, released a report stating that 80% of these products offer inferior sun protection or contain "worrisome" ingredients. They also note that most SPFs max out at about SPF 50 despite the fact that many sunscreens on the market claim to have much higher SPF ratings.

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What's the difference between sunscreen and sunblock?

As described above, there is no such thing as a true "sunblock." This is a marketing term formerly used to label sunscreens with high SPF. Manufacturers can no longer identify their products as sunblocks because these claims are inaccurate exaggerations. No sunscreen can completely block the sun's rays.

Do all tanning products contain sunscreens?

No, some don't. Tanning products such as self-tanners that don't contain sunscreen are required by the FDA to carry a warning label alerting consumers to the dangers of unprotected sunbathing.

What kind of sunglasses offer protection against UV rays?

Only those that provide 100% protection against UVA and UVB radiation, as stated on the label at the time of purchase, should be worn for protection.

Is sunscreen protection necessary in the winter?

Yes, UV radiation, though not as intense in the winter, still poses a threat, especially when rays reflect off snow. Skiers should also note that the degree of exposure to the sun's radiation increases 4% for every 1,000-foot increase in altitude. There is no safe time of year when it comes to UV radiation. The same applies to weather conditions. Even on a cloudy day, 80% of the sun's ultraviolet rays pass through the clouds and reach the earth.

Are a good sunscreen and sunglasses enough?

No, they are only one part of a complete sun-protection program. An effective program also includes limiting sun exposure and wearing protective clothing.

Do sunscreens expire?

Yes, sunscreens can lose effectiveness over time. Many sunscreen products are labeled with an expiration date to signal the limit of the product's effectiveness and stability. Sunscreens are typically designed to be stable for three years. Storing a sunscreen in the heat, however, can cause the active ingredients to lose effectiveness faster than storing it in a cool place. Discard any sunscreen that is past the stamped expiration date, and if you purchase a sunscreen without such a date, write the month and year of purchase on the bottle.

REFERENCES:

American Melanoma Foundation. "Facts About Sunscreen." <http://www.melanomafoundation.org/prevention/facts.htm>.

Environmental Working Group. "EWG's 2015 Guide to Sunscreens." <http://www.ewg.org/2015sunscreen/>.

Holman, Dawn M., et al. "Patterns of sunscreen use on the face and other exposed skin among US adults." Journal of the American Academy of Dermatology May 19, 2015. <http://www.eblue.org/article/S0190-9622(15)01352-3/abstract>.

United States. U.S. Food and Drug Administration. "Sunscreen." Sept. 30, 2016. <http://www.fda.gov/Drugs/ResourcesForYou/Consumers/
BuyingUsingMedicineSafely/UnderstandingOver-the-CounterMedicines/ucm239463.htm>.

Last Editorial Review: 9/30/2016

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Reviewed on 9/30/2016
References
REFERENCES:

American Melanoma Foundation. "Facts About Sunscreen." <http://www.melanomafoundation.org/prevention/facts.htm>.

Environmental Working Group. "EWG's 2015 Guide to Sunscreens." <http://www.ewg.org/2015sunscreen/>.

Holman, Dawn M., et al. "Patterns of sunscreen use on the face and other exposed skin among US adults." Journal of the American Academy of Dermatology May 19, 2015. <http://www.eblue.org/article/S0190-9622(15)01352-3/abstract>.

United States. U.S. Food and Drug Administration. "Sunscreen." Sept. 30, 2016. <http://www.fda.gov/Drugs/ResourcesForYou/Consumers/
BuyingUsingMedicineSafely/UnderstandingOver-the-CounterMedicines/ucm239463.htm>.

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