It’s pretty likely you’ll burn and the formula itself could trigger a reaction from your skin. “If a sunscreen product has deteriorated, then in theory there is a risk of chemical alteration of the ingredients.” And what does this mean? Well, there’s a greater likelihood of ‘contact reactions’ with the skin which means it could be irritating. There will also be a ‘fall in sun protection’ hence the burning.
Most sun creams have been designed to withstand a lot, “however if sunscreen containers are left in direct sunlight even the most stable of formulations can degrade.” Dr Patterson continues, “storage is important. Leaving your sunscreen baking in the sun, whether it’s on the beach, or in the back window of your car, may trigger degradation of the formula, and that renders the product useless.” The best place to store it? Somewhere shaded, preferably cool and dry.
So now we know what to do (and what not to do) to give our SPF the longest life possible. Just remember if in doubt, chuck the old stuff and pick up a new bottle - we know sun cream can be kinda spenny, but it’s worth protecting your skin no matter what