People still have burning questions about sunscreen.
We know regular use of sunscreen helps prevent certain skin carcinomas (melanoma, squamous cell, etc) and photoaging (wrinkles, etc).
But false claims are still casting shade. Help dispel them.
The higher the SPF, the better. Rumour, with conditions.
Put SPF numbers into perspective. SPF 15 blocks 93% of UVB rays...SPF 30 about 97%...and SPF 50 up to 98%. Inform that SPF numbers greater than 30 don’t seem to have additive benefits in most people.
For most patients, suggest a broad-spectrum (UVA/UVB) product with an SPF of 30...and SPF 50 for those with high skin cancer risk.
Educate that proper application matters most. For example, apply 30 mL (about the size of a shot glass) of sunscreen to all exposed skin about 15 minutes before sun exposure. And all SPFs should be reapplied every 2 hours...or sooner after swimming or sweating.
Sunscreen ingredients are harmful. Rumour, with conditions.
Data show that chemical sunscreens (avobenzone, oxybenzone, etc) are absorbed into the skin...but sunscreens are NOT shown to be harmful. Further studies are needed to establish toxicology data.
Recommend a nonabsorbable sunscreen (zinc oxide, titanium dioxide, etc) or sun-blocking clothing, if an option that doesn’t disrupt aquatic ecosystems is desired...or if birth defects are a concern in pregnancy.
Don’t rely on “reef-safe” labelling. There isn’t a standard definition...and no guarantee that products won’t harm the environment.
Sunscreen isn’t as important for people with darker skin. Rumour.
Higher melanin concentrations offer some degree of photoprotection by absorbing UV rays before they can penetrate skin cells.
But proper sun protection is recommended for EVERYONE...since skin cancer is just as dangerous to darker-toned patients.
Point to sheer sunscreens or those with darker tints or shades if patients are concerned about cosmetic issues with light-coloured versions.
Sunscreen can reduce vitamin D production. True.
Let patients know that regular use of UVB-blocking sunscreen or clothing can reduce vitamin D blood levels by up to 30%.
But this drop is still within acceptable levels for most healthy adults. Recommend vitamin D labs if patients show signs of deficiency.
See our FAQ, Shedding Light on Questions About Sunscreens, for illuminating info on types of sunscreens, application tips, and more.
- Pantelic MN, Wong N, Kwa M, Lim HW. Ultraviolet filters in the United States and European Union: A review of safety and implications for the future of US sunscreens. J Am Acad Dermatol. 2023 Mar;88(3):632-646.
- Canadian Dermatology Association. Sunscreen FAQ. https://dermatology.ca/public-patients/sun-protection/sunscreen-faq/ (Accessed June 10, 2025).
- Moradi Tuchayi S, Wang Z, Yan J, et al. Sunscreens: Misconceptions and Misinformation. J Invest Dermatol. 2023 Aug;143(8):1406-1411.
- Sambandan DR, Ratner D. Sunscreens: an overview and update. J Am Acad Dermatol. 2011 Apr;64(4):748-58.