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When it comes to the SPF level in sunscreen, a higher number doesn't always mean better protection. In this video dermatologist Dr. Ellen Marmur explains why.
The SPF number indicates the amount of sun exposure needed to cause sunburn on skin protected with sunscreen compared with skin not protected with sunscreen. A higher SPF value will offer more protection than a lower SPF value. For example, an SPF of 30 means it would take a person 30 times longer to burn when wearing sunscreen than the person would without sunscreen.
Not necessarily. Sunscreens with high SPF (sun protection factor) should provide more protection from the sun's ultraviolet (UV) radiation, which is a primary cause of skin cancers. But how well you apply the sunscreen and how often is nearly as important. Read instructions carefully and, in most cases, you need to reapply after going for a swim.
That said, the higher the SPF the better – until a certain point. For example, an SPF 15 sunscreen blocks 93 percent of UVB (ultraviolet B shortwave rays) – the chief cause of skin reddening and sunburn. Meanwhile, an SPF 30 sunscreen blocks nearly 97 percent. But the advantage of sunscreens above SPF 50, which blocks about 98 percent of UVB rays is questionable.
Sunscreens with an extremely high sun protection factor (SPF) only offer marginally better sunburn protection than high SPF sunscreens. Sunbathers often assume that they get twice as much protection from SPF 100 sunscreen as from SPF 50. In reality, the extra protection is negligible. Properly applied SPF 50 sunscreen blocks 98% of sunburn rays; SPF 100 blocks 99%.
There's another reason to avoid sunscreens with SPF over 50 -- they tempt people to apply too little sunscreen and stay in the sun too long. Your skin may be protected by UVB rays that cause sunburn, but could leave your skin exposed to damaging UVA rays that cause other kinds of damage.
The U.S. Food and Drug Administration has proposed prohibiting the sale of sunscreens with SPF values greater than 50+, calling higher SPF values “inherently misleading” due to the false sense of security that higher numbers impart. But the FDA has not issued a regulation that carries the force of law.
When used correctly, sunscreen with SPF values in the range of 30 to 50 will offer strong sunburn protection, even for people most sensitive to sunburn. Consumers should avoid sunscreen products labeled with anything higher than SPF 50+ and reapply sunscreen often, regardless of the SPF.
Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.