- It is safe to leave hand sanitizer in your car, though it probably isn’t the best place for storage.
- Some have warned about the risk of explosion when leaving hand sanitizer in a hot car, but this is very unlikely to occur and not a major cause for concern.
- Over time, the alcohol content in hand sanitizer evaporates, making it less effective – and there’s a chance of this process speeding up at high temperatures for an extended period of time.
- This article was medically reviewed by Tania Elliott, MD, who specialises in infectious diseases related to allergies and immunology for internal medicine at NYU Langone Health.
- This story is part of Insider’s guide on How to Kill Germs.
As long as the hand sanitizer has at least 60% alcohol content, it can kill germs on your hands, such as viruses and bacteria.
However, over time, the alcohol in hand sanitizer can evaporate and make it less effective. But as long as the container is closed, you should be able to leave it in your car temporarily – here’s why.
Is it safe to leave hand sanitizer in your car?
Hand sanitizers are labelled with an expiration date. This is the estimated date when the alcohol concentration will dip below 60% because of evaporation, making the sanitizer less effective. However, keeping a closed container in a car will not speed up this process.
“This evaporation is slowed as long as the cap, pump, or lid is tightly sealed as it is stored,” Graber says.
However, if the bottle is left open, the high temperatures in a car could cause the alcohol evaporation to speed up – so make sure to close the cap on your hand sanitizer when you’re done using it – whether it’s in the car, home, or elsewhere.
If it is open, it’s likely some of the alcohol has evaporated, so to be cautious, you might want to throw it away, because there’s no way to know for sure if it’s still effective.
Homemade hand sanitizers generally have a lower alcohol content than commercial products, and if you leave a DIY solution open in your car, you should assume it’s ineffective.
Another issue with homemade sanitizers is that they’re sometimes made using hydrogen peroxide. If sanitizers with hydrogen peroxide are exposed to UV light from being left in the sun, the hydrogen peroxide can decompose into water, making the sanitizer ineffective, Graber says.
How heat affects hand sanitizer
Overall, the Food and Drug Administration (FDA) recommends that hand sanitizer be stored between 59 to 86 degrees Fahrenheit.
Although hand sanitizer may still be effective at warmer or cooler temperatures, the FDA says that you should try to avoid “excessive heat above 104°F.”
At temperatures above 104°F for extended periods of time, there is a higher risk of the alcohol content evaporating, Graber says. A car can heat up very quickly in the sun, so it’s better to leave your hand sanitizer in a place where the temperature is cooler.
In addition, there are some concerns that evaporated alcohol from hand sanitizer in hot temperatures could cause combustion or explosion – but this is very rare.
The National Fire Protection Association even posted a video about the fire risk of hand sanitizer, explaining that the high alcohol content could make it potentially flammable.
“While infrequent, there have been cases in the recent past [where] reflecting light placed through a clear bottle was able to focus onto a combustible surface and cause a fire,” one Wisconsin Fire District claimed.
However, hand sanitizer causing a fire or explosion in a vehicle is very unlikely, Graber says, and it is not a major cause for concern.
A quick test for your hand sanitizer
The biggest risk of hand sanitizer left in your car is decreased effectiveness – especially if the container was left fully or partially opened.
If you’re worried about the effectiveness of your hand sanitizer, Graber recommends that you “eyeball” how thick the solution is.
“As the alcohol evaporates from the solution, it will become more thick. It will ‘swish’ less and less in the bottle and it will take increasingly longer for the solution to dry when it is applied to your hands,” he says. “When it reaches this point, it is time to replace the solution with a new bottle.”