Share on Pinterest
David Molina Grande/Westend61/Offset Images

If you don’t have access to soap and water on the go, is it still safe to use hand sanitizer that’s been left in a hot car all day?

To help get rid of germs in a pinch, it’s a good idea to have sanitizers on hand, including your workspaces, kitchen, personal bag, and even your car. However, leaving hand sanitizer in a hot car isn’t necessarily a good idea because the product can lose its effectiveness.

Find out just how effective a hand sanitizer might be once left in a hot car, and how you can keep your hands as germ-free as possible.

If you’re like most people in the middle of the COVID-19 pandemic, you may keep hand sanitizers in your car and other places where you don’t have access to regular soap and water.

While leaving hand sanitizer in your car isn’t all bad, there are some safety considerations to be aware of.

Active ingredients become less effective when exposed to sunlight

Long-term heat and sunlight exposure can break down the alcohol content in traditional hand sanitizers. So it’s possible that the alcohol won’t kill germs as effectively.

In a car, hand sanitizer may be exposed to heat via direct sunlight. However, for the product to significantly get destroyed, the sanitizer would have to be directly exposed to sunlight for a long period of time.

This could mean the difference between leaving the hand sanitizer in a hot car while grocery shopping versus during a whole workday.

As a rule of thumb, alcohol-based hand sanitizers shouldn’t be stored in areas above 105°F (40°C). This will make them expire more quickly.

Was this helpful?

Hand sanitizers become less effective if used after the expiration date

Aside from keeping your alcohol-based sanitizer away from heat and direct sunlight exposure, it’s also important to keep tabs on the product’s expiration date.

These types of hand sanitizers tend to be good for up to three years. After this time, the alcohol may be less effective at killing germs.

All commercial hand sanitizers are required to list expiration dates by law. If you’re unsure of your product’s expiration date, you may be able to tell by the smell and consistency. Any changes could mean the hand sanitizer has gone bad.

While expired hand sanitizer won’t necessarily be harmful to your skin, there’s no guarantee that the product will work after the expiration date. This means the product may no longer kill germs on your hands as it should.

Effectiveness of hand sanitizers also depends on their correct use

Also, an alcohol-based hand sanitizer is only effective if you use it correctly. Make sure you apply enough product so that your hands are completely wet. Then, rub your hands together for at least 20 seconds, or until they’re completely dry.

Alcohol-based sanitizers won’t explode if left in a hot car

Alcohol itself is flammable. But contrary to theories on the internet, it’s unlikely for hand sanitizer to explode if left in your car. Alcohol-based sanitizers may catch fire or explode when exposed to flames, but that’s far hotter than everyday sun exposure in your car.

Was this helpful?

Your go-to hand sanitizer could degrade if left inside your car in direct sunlight for several hours. However, these effects aren’t as likely if you keep the hand sanitizer in a shaded part of your car, such as inside a glove compartment or the interior door pocket.

Aside from your car, you should also consider keeping your sanitizers away from heat and direct sunlight outdoors. Consider storing your bottle in a cloth bag for added protection.

Make sure any hand sanitizer you use contains at least 60 percent alcohol. This is the minimum amount necessary to kill most germs. Alcohol-free sanitizers may not degrade as quickly in heat, but these products aren’t known to be as effective as those containing alcohol.

Most commercial hand sanitizers contain a form of alcohol to kill germs. Only two are approved by the FDA:

  • isopropyl alcohol (found in rubbing alcohol)
  • ethyl alcohol

These are considered the “active” ingredients in such products.

To help offset the strong chemical scent, many hand sanitizer manufacturers add additional ingredients such as fragrances. Moisturizers, like aloe vera, may also be added to help prevent your skin from drying out.

Alcohol-free hand sanitizers don’t pose issues with sensitivity to heat and sunlight exposure, but before you consider these alternatives, it’s important to know that such products aren’t proven to work as well against germs compared to their alcohol-based counterparts.

Hand sanitizers are unlikely to explode in a hot car, but they may lose some of their efficacy when left in direct sunlight for a long time. This is because alcohol, the active ingredient in most consumer antiseptics, can break down and lose their ability to kill germs.

As a rule of thumb, you shouldn’t leave hand sanitizers in direct sunlight. It may be safe to leave these products in your car only if they’re stored in cool, dark places such as your glove compartment.

Don’t use hand sanitizers beyond their expiration dates. Also, it’s important to wash your hands as often as possible, using hand sanitizer primarily as a backup only when soap and water are unavailable.

The FDA maintains that hand sanitizers have not been proven to be more effective than traditional hand washing.