Between commuting to work, chauffeuring the kids around, and running errands, sometimes it can feel like you spend more time in your car than anywhere else. And because of how frequently you may be behind the wheel, it’s only natural to keep your car stocked full of necessary items: Advil, a Speed stick, some extra mascara—that sort of thing.
However, while having such products on hand is surely convenient, storing them in the car can ruin them—and, in extreme cases, even pose a threat to your health. Herewith, we’ve compiled a list of items that you should never, ever keep in the car.
“Pharmaceutical manufacturers recommend most of their products be stored at a controlled room temperature of 68 to 77 degrees,” Dr. Skye McKennon, PharmD, explained to the New York Times. And seeing as the warmer months can bring the temperature inside your car up to an average of 116º Fahrenheit, it’s best to bring your medications inside if you want to maintain their efficacy.
If you’ve ever accidentally left your phone out in the sun while lounging by the pool, then you already know that electronics and extreme temperatures do not play well together. When devices are left in these conditions for long periods of time, they can suffer some serious long-term damage, and you might return to your vehicle to find that your batteries are permanently damaged.
Though keeping an extra bottle of sunscreen in the car is commendable, it’s unfortunately also ineffective. Every time your car overheats, the ingredients in the sunscreen that protect your skin from the sun become less and less effective, rendering the bottle of lotion pointless.
“When sunscreen is stored in a high temperature, the effectiveness decreases, and the sunscreen becomes less stable and reliable,” Dr. Fredric S. Brandt, MD, a cosmetic dermatologist, explained to Refinery29. “When it gets hot or is stored above 77º Fahrenheit, the potency is destroyed, and the sunscreen will degrade.”
Even if you have a pair of glasses that you use specifically for driving, you should never keep them in your car. On especially scorching days, the rays of the sun can cause the plastic of the frame melt and warp, permanently damaging the fit.
There’s a reason that things stored in aerosol cans—like hairspray, spray paint, and deodorant—all have storage temperature recommendations printed on the bottle. If left out in extreme temperatures, these cans can expand and explode, and their contents are highly flammable.
Plastic Water Bottles
If you drink from a plastic bottle that’s been left sitting in the car for too long, you could end up inadvertently consuming harmful substances like BPA that have leaked from the plastic into the water. And what’s more, when Idaho Power left a water bottle on the seat of a car in direct sunlight, it magnified the sun’s rays and set the car seat on fire.
According to the Department of Agriculture, leaving food out at an unsafe temperature is one of the leading causes of food-borne illness. To ensure that perishable groceries are safe for consumption, the department recommends leaving your food out in temperatures above 40º Fahrenheit for no longer than two hours, or just one hour when the temperature is above 90º Fahrenheit.
Wet clothing isn’t going to dry if left in the car. Instead, these damp items will become moldy and breed bacteria, which can potentially cause an infection when worn again.
Crayons might keep the kids entertained on long car rides, but these art supplies will melt and stain your seats as outside temperatures climb. So unless you want the inside of your car to look like a Jackson Pollock painting, you should always double-check that the crayons have been safely stored somewhere in the house after every use.
If your flashlight is battery-powered, then you should avoid storing it anywhere in your car. When exposed to high temperatures (like those of an overheated car), batteries can leak and lose power, making them—and thusly, your flashlight—unusable.
Quality cosmetics cost a pretty penny, so it’s especially important to make sure that you treat them well and get the most out of them as possible. And while keeping a spare lipstick or tube of mascara in the car makes it convenient to gussy up on the go, the temperature of the car can melt or freeze the pricey products.
According to insurance agency Geico, the flammable liquid inside a lighter can leak out of the container when the temperature inside your car becomes too hot, creating a serious fire hazard.
If you’re worried about having fresh breath on the road, then opt for a tin of mints over a pack of gum. When left out in the sun, gum becomes gooey and sticks to everything—and in the winter, it becomes frozen solid, rendering it flavorless (and dangerous to your teeth).