Does hand sanitizer kill coronavirus? How it works and when you should use it

Hand sanitizer: the convenient, on-the-go method of cleaning your hands. The only problem is, hand sanitizer may not be as effective as washing your hands, according to the Centers for Disease Control and Prevention. Learn how and when to properly use hand sanitizer, when you should just wash your hands with soap instead and how to protect yourself from viruses (including coronavirus) and bacteria. 

As with many other coronavirus-related products, panic buying has cleared the shelves of real-world and online retailers of cleaning products and other essentials, or introduced high pricing from third-party resellers.

Read more: Why you shouldn't make your own hand sanitizer.

How does hand sanitizer work?

Hand sanitizers are a convenient way to clean your hands when soap and water aren't available. Often used on the go, hand sanitizers contain ethyl alcohol, isopropyl alcohol or both to kill bacteria and viruses on your hands. Alcohols have long been known to kill germs by denaturing the protective outer proteins of microbes and dissolving their membranes. 

The CDC recommends using a hand sanitizer with at least 60% alcohol, as sanitizers with lower concentrations of alcohol aren't as effective at killing germs. Even up to 90% alcohol is preferable to ensure that hand sanitizer completely kills germs rather than just reducing their growth on your hands. 

Hand sanitizer vs. washing your hands

According to the CDC, hand sanitizer is not as effective at killing germs as washing your hands with soap and water. The CDC says that washing your hands is a better tactic for removing certain viruses and bacteria, such as Cryptosporidium (causes diarrhea) and norovirus(stomach bugs).

Part of the reason that hand sanitizer isn't as effective as washing your hands is that people often wipe their hands before the hand sanitizer dries completely. Also, if your hands are dirty or greasy, hand sanitizers may not work because they can't penetrate dirt and grease like soap can. 

Read more: Face masks aren't the answer to preventing coronavirus

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The World Health Organization recommends using hand sanitizer only as an alternative when you don't have access to soap and water. Like the CDC and WHO, the National Institutes of Health also recommends washing your hands whenever possible. The US National Library of Medicine has a helpful topic page where you can find everything from quick facts to in-depth scientific studies on hand-washing.

When should you use hand sanitizer?

Again, you should only use hand sanitizer when soap and water aren't available, according to the CDC. Ideally, you'd never use hand sanitizer with greasy or dirty hands -- try to find soap and water instead. 

Hand sanitizer can also serve a purpose in hospitals and clinics: If you visit someone in the hospital, using hand sanitizer after your visit can help prevent the spread of diseases (unless the person is sick with a bacterium called Clostridium difficile, or C. Diff, in which case the CDC says you should still wash your hands). 

Can hand sanitizer protect you from viruses?

Hand sanitizers can help protect you from infections -- both viral and bacterial -- when used correctly and in the right scenarios. This means applying a hand sanitizer that is at least 60% alcohol, using the directed amount (read the label), rubbing it in completely and waiting for it to dry before doing anything else with your hands. 

Some research has shown that hand sanitizer can actually increase your risk of some infections, such as norovirus, possibly by way of bacterial resistance. Hand sanitizer has also been shown to be less effective than hand-washing at preventing the flu. So far, however, the evidence remains unclear, so it's still best to use hand sanitizers if soap and water aren't available.

Read more: The best thermometers for cold and flu  

Hand sanitizer is recommended for use by healthcare professionals in clinical settings, as it's been shown to reduce the spread of numerous hospital-borne bacteria and viruses, including Methicillin-resistant Staphylococcus aureus (MRSA), which is considered a superbug. 

The best way to protect yourself from sickness

During cold and flu season, your best defense is the flu vaccination coupled with regular hand washing, as well as basic tactics for keeping your immune system ready to fight off illnesses: Exercise, get enough sleep, hydrate and eat nutritious foods. 

Hand hygiene -- washing and sanitizing when necessary -- should be something you do multiple times per day. Everyone should wash their hands after using the restroom, handling any form of waste, before and after eating, after touching an animal or animal food or toys and after treating a wound. The CDC provides a helpful list of scenarios that require hand-washing.

Other things that can help include: keeping surfaces in your home clean, disinfecting your electronics, staying away from people who are sick and avoiding densely populated areas, such as public transportation, if possible.    

The CDC also recommends that you avoid touching your eyes, nose and mouth, and that you cough and sneeze into tissues and throw the tissues away. Additionally, you should stay home when you're sick to prevent the spread of any infectious diseases. These preventative guidelines go for all infectious diseases, including the novel coronavirus.

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