Hand sanitizers and hot cars don’t mix. The heat and exposure to sunlight may break down the alcohol content in hand sanitizer, making it far less effective. That’s not good at all, at a time when we’re all trying to stay safe from coronavirus germs. The solution, of course, is not to leave hand sanitizer in your car where it might overheat, but to carry it with you.

While keeping hand sanitizer on you instead of in your car, is the best solution, note that for short periods of time, it’s fine to keep the stuff in your car. Going shopping at the local grocery store? No problem. Leave the hand sanitizer in your car. Spending the day at the office? Nope. Take the hand sanitizer with you.

According to the FDA, what you want to avoid is storing hand sanitizer in temperatures above 105°F (40°C). That’s the temperature at which hand sanitizer begins to degrade and lose its effectiveness. Note also the expiration date on your stash of hand sanitizer, though that’s probably not a problem for most of us. We’ve all been using these alcohol-based hand gels like crazy, since March, when the pandemic ran out. Fat chance your container of hand sanitizer would last long enough to expire.

Note that the effectiveness of hand sanitizers is also dependent on how you use them. You should use enough of the product to wet your hands completely. Once your hands are nice and wet, rub in the hand sanitizer for at least 20 seconds, or until your hands are all dry.

If you must keep hand sanitizer in your car, at least put it inside the glove compartment, or in the door pocket. That will at least keep your stash of hand sanitizer out of direct sunlight. But the heat is definitely going to have an effect, especially if you leave the hand sanitizer in your car over long periods of time— which is definitely not something we advise.