It’s true that SPF 15 provides more protection than SPF 4, and 30 is better than 15. So, it stands to reason that the higher the SPF number, the better, right? Not necessarily.
According to Dr. Steven Wang, a dermatologist at Memorial Sloan-Kettering Cancer Center, choosing the right SPF, or sun protection factor, is not so cut and dry. A sunscreen’s SPF factor has to do with how much protection it provides against UVB rays – the sun rays that play the biggest role in skin cancer. The higher the number, the more the sunscreen will block out these rays. However, the degree to which the level of protection increases with higher SPFs is very small with SPFs of 50 and higher. So, dermatologists don’t recommend going beyond 50 or below 30. Also, it’s important to note that most people don’t wear the recommended amount of sunscreen. In fact, most people only wear about one-third the amount they should. So they will only experience one-third the level of protection listed on the bottle of sunscreen.
Another important factor in choosing a sunscreen is UVA protection. While UVB, the rays that cause your skin to burn, play the biggest role in skin cancer, UVA rays damage the skin in ways that aren’t as obvious. For instance, sunscreen that protects only against UVB rays will prevent you from becoming sunburned, but your skin will still be susceptible to the aging effects of the sun (wrinkles, spots) and to the radiation caused by UVA rays. So, someone who wears a sunscreen boasting a very high SPF factor may believe they’re totally protected from the sun, but the SPF factors only reflect UVB protection. Look for sunscreen that’s labeled multi spectrum, broad spectrum, or UVA/UVB protection which will have UVA blocking ingredients like zinc oxide, titanium dioxide, avobenzone, ecamsule, and oxybenzone.
No matter how diligent you are about wearing sunscreen, remember to see your dermatologist once a year for a skin examination to identify any signs of skin cancer. To learn more about skin cancer, how it’s diagnosed, and questions to ask your doctor, read our Skin Cancer Patient Guide.