Greater efficacy of SPF 100+ sunscreen compared to SPF 50+ in sunburn prevention during five consecutive days of sunlight exposure: A Randomized, Double-Blind Clinical Trial

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J Am Acad Dermatol


BACKGROUND: Beach vacations are high-risk settings for overexposure to ultraviolet (UV) radiation.

OBJECTIVE: To compare the sunburn protective efficacy of SPF 50+ and SPF 100+ sunscreens under actual use at the beach METHODS: A prospective, randomized, double-blind, single-center, split body/face study of 55 healthy subjects. Each subject applied both sunscreens to randomized side of the face/body for up to 5 consecutive days. Blinded clinical evaluation of erythema by a single grader and objective instrumental assessments, colorimetry and diffuse reflectance spectroscopy, were performed the morning following each sun-exposure.

RESULTS: After five days, 31 (56%) subjects had more sunburn on the SPF 50+ side and 4 (7%) on the SPF 100+ side. Overall, mean erythema intensity demonstrated statistically significantly less erythema on the SPF 100+ side compared to SPF 50+. The first observation of sunburn exclusively on the SPF 50+ side occurred after one day whereas that for SPF 100+ occurred after three days of sun-exposure.

LIMITATIONS: Only initial sunscreen application was monitored, only one skin-phototype I subject was recruited, and subjects were recruited from local beach area.

CONCLUSION: SPF 100+ was significantly more effective in protecting against UV-induced erythema and sunburn than SPF 50+ in actual use within a beach vacation setting.

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ePub ahead of print