Sunscreen products with a sun protection factor (SPF) of 100+ are significantly more effective in protecting against sunburn than SPF 50+ sunscreen products, according to the results of a natural sunlight, single-exposure, split-face, randomized, double-blind study (ClinicalTrials.gov identifier: NCT02952235)1 published in the Journal of the American Academy of Dermatology.
The primary endpoint of the study was a bilateral comparison of sunburn on left- and right-side treatment areas. Scoring used a condensed 2-side difference scale: L1, participant’s left side noticeably more sunburned than his/her right side; 0, no difference in sunburn between the participant’s left and right side; R1, participant’s right side noticeably more sunburned than his/her left side. The secondary endpoint was erythema score using a 5-point scale: 0, no burn; 1, possible burn; 2, defined redness; 3, severe sunburn; and 4, edema and blisters.2
A total of 199 individuals were randomly assigned to treatment: 99 in group 1 (left SPF, 50+/right SPF, 100+) and 100 in group 2 (left SPF, 100+/right SPF, 50+). The study population comprised 115 men and 84 women; mean age of the participants was 37.4±16.3 years. The average exposure duration of the participants was 6.1±1.3 hours.
When blinded evaluation was performed the day after the sun exposure period, the SPF 50+ protected side of the face was reported to be significantly more sunburned than the SPF 100+ protected side of the face in 55.3% (110 of 199) of the participants, with 5.0% (10 of 199) of participants exhibiting results to the contrary (P <.001).
Sunburn severity, based on the mean increase in postexposure erythema score, was significantly lower on the SPF 100+-protected side of the face compared with the SPF 50+-protected side of the face (0.14±0.31 vs 0.330±0.44, respectively; P <.001). The highest postexposure erythema scores were reported on the SPF 50+ side of the face in both treatment groups. Overall, 40.7% (81 of 199) of participants had postexposure scores ≥1 on the SPF 50+-protected side vs 13.6% (27 of 199) of participants on the SPF 100+-protected side.
The investigators concluded that SPF 100+ sunscreen products provide a level of enhanced sunburn protection that is observed after a single day of sun exposure. These findings suggest that sunscreen products with SPFs >50+ may offer improved sunburn protection in certain settings, having important implications for photoprotection recommendations as part of skin cancer prevention.
- Williams JD, Maitra P, Atillasoy E, Wu MM, Farberg AS, Rigel DS. SPF 100+ sunscreen is more protective against sunburn than SPF 50+ in actual-use: results of a randomized, double-blind, split-face, natural sunlight exposure, clinical trial [published online December 29, 2017]. J Am Acad Dermatol. doi: 10.1016/j.jaad.2017.12.062
- Ou-Yang H, Jiang LI, Meyer K, Wang SQ, Farberg AS, Rigel DS. Sun protection by beach umbrella vs sunscreen with a high sun protection factor: a randomized clinical trial. JAMA Dermatol. 2017;153(3):304-308.