Recently expired sunscreen: can I use it as a last resort?

BarcelonaIt's 7:15 in the morning. The boy is about to go on his first trip to the pool of the first week of summer camp. We take out the sunscreen and... it's been expired for two months! The shops are still closed. What do we do?

The answer from dermatologist Alejandro Fernández, from Sanitas' CIMA Hospital, is clear: "When we're asked if you can use expired sunscreen, the advice is no." And not just because the sunburn becomes less effective. "We've seen serious adverse reactions," says the specialist.

Why do creams expire?

The chemical composition of sunscreens changes over time, especially if they haven't been stored properly, and some of the ingredients can end up causing irritation, eczema, or dermatitis. The dermatologist sums it up with a culinary comparison: "Creams are like mayonnaise." Made up of water and oil, they require emulsifiers to hold the mixture together. When stability deteriorates—especially if the cream has come into contact with oxygen—the two phases can separate. "The active ingredients decompose and can generate new substances that haven't been tested on the skin," explains the specialist.

Are there exceptions?

The price or origin of the burn is no guarantee. Just because it's the best burn from our trusted pharmacy doesn't make it more resistant to the passage of time than a supermarket. "It's a question of the ingredients, not the point of sale," warns the doctor.

However, there are nuances. If the burn has been well stored, in a cool, dark place, and it's been just a short time since the expiration date, "nothing may happen," the dermatologist admits. But he insists: "It's not at all advisable." It's like playing Russian roulette: we don't know if it's going to cause a reaction until we've applied it. Therefore, "it's better to be proactive and not take any risks," says Fernández, leaving the expired cream away from our skin and in the pharmacy container.