Summer is coming to a close and while we’re swapping out our bathing suits and sundresses for ankle boots and jeans, our beauty regimen is changing as well. If you’re anything like us, you keep a vast collection of sunscreens to protect your complexion amid hot temps. However, we never quite know what to do with leftover bottles after summer's sunny days end. We usually just end up leaving them stashed in a beach bag throughout the winter—but is it better to toss them and start fresh next season? We sought out dermatologist Melanie Palm, MD, MBA to find out.
It turns out that most sunscreens, if stored in airtight bottles at around room temperature, can last for another season. “It’s fine to leave your sunscreen in your beach bag, so long that it is stored in a place at a reasonable temperature (usually within 20 degrees—plus or minus—of room temperature),” Palm tells InStyle. “Some of the sunscreen ingredients or stabilizing agents may become unstable with extremes of temperature, especially extreme heat.”
Another concern we've always had is about sunscreen expiration. How exactly do we know when it’s time to stock up with new bottles? “Typically, the shelf life is 1 to 3 years,” Palm notes. That said, it’s crucial to check the date and toss the sunscreen if it has expired. “If a sunscreen product has separated, or is discolored, you also cannot rely on its effectiveness and it should be discarded.”
Taking note of the type of formula is also recommended by Palm. “Mineral based sunscreens (zinc oxide and titanium dioxide) are unlikely to lose effectiveness over time,” she says. However, chemical sunscreens (e.g. avobenzone, homosalate, octocrylene), are more likely to lose stability over time. According to Palm, this is especially true for products that contain avobenzone, as this product degrades quickly in the presence of light if not properly stabilized by other ingredients.
Palm also points out that if we're using as much of the stuff as we should we shouldn’t even have to worry about storage. “A typical sunscreen container has only 4 oz. of sunscreen and a typical full body sunscreen application should use a full 1 oz. of product,” she adds. “This means only four applications per bottle (most of us under-apply by about 50 percent!)—so really bottles should easily be used up over the season.”
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