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SPF50 vs SPF100: Which Offers Better Protection?

SPF 100+ sunscreen appears to offer better protection against sunburn at the beach compared with SPF 50+ sunscreen, according to the findings of a recent study.

“Beach vacations are high-risk settings for overexposure to UV radiation,” the researchers said. They compared the efficacy of SPF 50+ with SFP 100+ sunscreens under actual beach use among 55 healthy participants. All participants applied sunscreen SPF 50+ to one side of their face and body and SPF 100+ sunscreen to the other half for up to 5 consecutive days. On the mornings after sunscreen exposure, participants underwent blinded clinical evaluation for erythema by a single grader and objective instrumental assessments, colorimetry, and diffuse reflectance spectroscopy.
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The researchers found 31 (56%) participants had more sunburn on the SPF 50+ side compared with 4 (7%) on the SPF 100+ side after 5 days of sunscreen. “Overall, mean erythema intensity demonstrated statistically significantly less erythema on the SPF 100+ side compared to SPF 50+,” they said.

In addition, the first observed sunburn occurred on the SPF 50+ side after one day while the first sunburn on the SPF 100+ side occurred 3 days after sun-exposure.

“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,” the researchers concluded.

However, their study was limited due to only including participants with skin phototype I who were recruited from a local beach area and only monitoring the initial application of sunscreen.


Kohli I, Nicholson CL, Williams JD, et al. 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 [published online September 19, 2019]. J Am Acad Dermatol. doi:10.1016/j.jaad.2019.09.018

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