A number of social media posts are wrongly claiming that using sunscreen raises people’s risk of skin cancer. These claims are based on a classic misunderstanding.

The posts, which we’ve seen on Facebook and on Instagram, all cite an article on a website called the People’s Voice that we have fact checked many times before. This article describes a study from 2023 that used data from the UK Biobank to compare skin cancer rates in different groups of people.

The study in question found that people who were frequent or very frequent users of sunscreen were also more likely to develop skin cancer. From this, the website article and social media posts conclude that “using sunscreen massively increases the risk of three major types of skin cancer”.

But this doesn’t follow at all—and it isn’t true. Instead it’s a clear case of what’s sometimes called “confounding by indication”.

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For example, people who are about to visit malaria zones are more likely to take anti-malaria tablets—and also more likely to catch malaria. People experiencing hair-loss are more likely to take hair-loss treatments—and to lose more hair. And of course people who are about to go in the sun are more likely to use sunscreen—and also more likely to develop skin cancer.

This doesn’t mean that using sunscreen causes skin cancer. It means that something else—sun exposure—leads to both. So people who use more sunscreen are probably exposed to more sunlight, on the whole, which puts them at higher risk of skin cancer that the sunscreen doesn’t completely prevent.

The study itself explains this, saying the paradox “can be explained by greater exposure to UV light and/or a lack of reapplication of sunscreen throughout the day, or due to increased use of sun protection following skin cancer diagnosis”.

Indeed it specifically says: “these findings demonstrate the importance of adequate and frequent sunscreen use and minimization of exposure to UV light, particularly in individuals with fair skin”.

One of the study authors has even been interviewed for an article about what he calls “the sunscreen paradox”.

Far from being a cause of skin cancer, sunscreen is one of the ways that people can reduce their risk, according to NHS sun safety advice.

Sunscreen must be used correctly in order to maximise the protection it gives, and it may be less effective than seeking shade or covering up with clothes, but research over the years shows that it does reduce the harmful effects of sun exposure, including the risk of cancer.