Does Hand Sanitizer Kill Viruses?
If handwashing is not an option, hand sanitizers can help protect you from Covid-19. Here's how to choose the right kind of hand sanitizer and use it correctly to kill coronavirus and other viruses that can make you sick.
Hand sanitizers have been a saving grace during the Covid-19 pandemic. They are an easy way to lower the risk of contracting the coronavirus when soap and water are not readily available. So people often turn to hand sanitizers to kill viruses.
But not all hand sanitizers work—and some may actually do more harm than good. The Food and Drug Administration (FDA) has been cracking down on hand sanitizer products that say they contain ethanol or ethyl alcohol, but actually contain methanol or 1-propanol, two different types of alcohol that can be toxic—even lethal—when absorbed through the skin or ingested.
The FDA now keeps a running list of hand sanitizers to avoid. Check it out before you make your next purchase.
Hand washing vs. hand sanitizer
First things first: Using a hand sanitizer is not a replacement for washing hands with soap and water for at least 20 seconds. That’s about as long as it takes to sing the “Happy Birthday” song twice. Hand washing is still the No. 1 way to get rid of germs on your hands. If you can’t get to a sink, hand sanitizers are the next best thing, the Centers for Disease Control and Prevention (CDC) points out.
But does hand sanitizer kill viruses? It’s the alcohol that inactivates the germs. There are many types of alcohol, but only two belong in your hand sanitizer, explains Jack Caravanos, clinical professor, NYU’s College of Global Public Health in New York City. These are ethanol or isopropyl.
“Most of the hand sanitizer formulations are made of ethanol,” he says. Your hand sanitizer should contain more than 60 percent alcohol to be effective, he adds. “When you flip the label, see the words ‘active ingredients,’ and that should be ethanol or isopropyl.”
So what is the other 40 percent? “The non-alcohol portion of hand sanitizer comprises moisturizer and/or a thickening agent,” Caravanos says. Moisturizers help the skin from becoming too dry from the alcohol. Thickening agents prevent the solution from splashing all over the place when applied.
Alcohol-based hand sanitizers work by inactivating many types of germs, according to the National Academy of Sciences. “Well-manufactured and preserved sanitizers can inactivate some viruses such as the flu and corona, but scarcely affect the naked ones like papilloma (warts), adeno (cold), and noro (diarrhea),” says Nwadiuto Esiobu, PhD, professor of microbiology and biotechnology at Florida Atlantic University in Boca Raton.
Alcohol-based hand sanitizers reduce the level of viruses below the amount needed to infect a person, Esiobu says. “They destabilize the viral envelope that bears the spike.” One key feature of SARS-CoV-2, the virus that causes Covid-19, is the protein spikes that cover its surface. The virus uses these spikes to bind to and enter human cells. When the viral envelope is destabilized, infection is less likely.
Hand sanitizers can only do their job if they are used correctly. Some people don’t use enough or may wipe it off before it has dried and completed its task. The CDC suggests covering all surfaces of your hands with sanitizer and rubbing your hands together until they feel dry.
“Increasing the exposure time also allows for [breakdown] of the spike protein. So, you get best results when you don’t wipe off the sanitizer,” Esiobu says. This typically takes about 30 seconds, according to the World Health Organization.
With hand washing, it’s the physical lathering and scrubbing that removes germs, dirt, and grime from your hands.
By contrast, sanitizers don’t get rid of dirt, and they also may not get rid of all types of germs or pesticides and heavy metals. Hand sanitizers work well in health care settings where hands come into contact with germs but are not otherwise dirty or greasy.
It’s not just how but when you wash your hands that matters. You should wash your hands before, during, and after preparing food; before and after caring for someone at home who is sick; and after using the toilet, blowing your nose, coughing, or sneezing.
Choosing the right hand sanitizer
The hand sanitizer market is flourishing and many companies have thrown their hat in the ring. But “go with a name brand product,” Caravanos says. “There are a lot of knockoffs out there and the recent FDA action shows that this can be dangerous.” Even if it is not a toxic form of alcohol, hand sanitizer can cause alcohol poisoning if swallowed, and it is also flammable.
Hand washing is one part of a Covid-19 prevention strategy that also includes wearing a face covering when social distancing is not possible, disinfecting shared surface, and staying home when you are under the weather.
- Food and Drug Administration: "FDA urges consumers not use certain hand sanitizer products"
- Food and Drug Administration: "FDA updates on hand sanitizers consumers should not use"
- Centers for Disease Control and Prevention:"How to Protect Yourself & Others"
- Jack Caravanos, DrPH, Clinical Professor, NYU's College of Global Public Health, New York City
- National Academy of Science: "Does hand sanitizer kill the coronavirus?"
- Nwadiuto Esiobu, PhD, Professor, Microbiology and Biotechnology, Florida Atlantic University, Boca Raton, Florida
- World Health Organization: "Hand Hygiene: Why, How & When?"