Are you using hand sanitizer effectively?

Photo by Kelly Sikkema on Unsplash


As concern about Covid-19 rises, people are panic buying. Many retailers are experiencing a shortage of many products. One of them is hand sanitizer. 

As discussed in the previous post, the best way to protect yourself and the people around you is by washing your hands frequently. But what if you don’t have access to water and soap when you are in public transport or out on your grocery run, where you will be touching door handles, grocery cart, etc. Hand sanitizers can be handy during those situations. 

There are two main types of sanitizers: alcohol-based or non-alcohol based. 

Alcohol-based sanitizers are found to be effective in reducing the number and type of microbes on your hands. Studies have shown that alcohol-based sanitizers are effective against bacteria such as the notorious E.coli and Methicillin-resistant Staphylococcus aureus (MRSA). It is also effective against viruses, including influenza A, hepatitis A virus, Ebola virus, and coronaviruses (SAR-CoV-2 and MERS- CoV).  

Why alcohol? How does it work?

Alcohol (mainly isopropyl alcohol and ethyl alcohol) have bactericidal, fungicidal and virucidal properties. The way it works is by the denaturation of proteins. Denaturation is a process where the protein structure unfolds, hence rendering the protein inactive and loses its function. At 60-80%, ethyl alcohol is potent in killing viruses. Denaturation of the protein capsule in a virus particle leads to exposure of its DNA/RNA content. Without the protective layers and structural integrity, DNA/RNA content in virus particles are harmless and the viruses cannot infect host cells and multiply.

Is 100% alcohol better?

The answer is no. Denaturation of proteins works better when water is present. Pure alcohol evaporates quickly and is less effective in denaturing proteins. There are some variations in the percentage but anything between 60% and 80% would be effective. CDC recommends using a hand sanitizer with at least 60% alcohol if soap and water are not available.  Anything less than 60% would be less effective, hence increasing the risk of leaving harmful germs on your hands.

Does alcohol-free hand sanitizer actually work?

Alcohol-free hand sanitizers aren’t recommended by the CDC. They do not kill as many germs as most alcohol-free products claim. Instead of using alcohol as a disinfecting agent, alcohol-free sanitizers use other agents such as benzalkonium chloride or triclosan as a substitute. These substitutes have antimicrobial activities but there aren’t enough studies on their effectiveness against viruses. Besides, some studies have indicated that benzalkonium chloride may be associated with staphylococcal antimicrobial resistance.

The downside of alcohol-based sanitizers

Although alcohol-based sanitizers are effective against most germs, they might not be as effective in cleaning heavily soiled or greasy hands and do not eliminate all types of germs.   

When using hand sanitizer, apply the product to the palm of one hand (read the label to learn the correct amount) and rub the product all over the surfaces of your hands until your hands are dry. Alcohol can also cause dry skin and irritation. That can discourage people from sanitizing their hands as frequently. For this matter, most hand sanitizers contain emollients such as glycerin, which will help soften and moisturize your skin. 

If you are looking to use hand sanitizers to protect yourself against Covid-19, your best bet is still alcohol-based hand sanitizer, just made sure the alcohol content is over 60%.  

Unfortunately, due to the shortage of sanitizing products in the market, many have resorted to making their own sanitizers at home. Bear in mind, vodka (40% alcohol) doesn’t contain enough alcohol for it to be an effective disinfectant. The same goes for alcohol-free sanitizers. 

How to use hand sanitizers: 

  • Apply enough product (usually 2mL, read the product label to learn the recommended amount) to the palm of one hand. 
  • Rub the product all over the surfaces of your hands, including between your fingers, and under your nails. 
  • Keep rubbing your hands until your hands feel dry. This should take around 20 seconds. 
Credit: CDC

Beware of FAKE news on social media claiming victims suffered a burn injury from using alcohol-based hand sanitizers and caught on fire. 

If you use the hand sanitizer properly until your hands feel dry, all alcohol would have evaporated. The only residues remaining would be the moisturizing components of the hand sanitizer to protect your skin from dryness and irritation. 

Fact:
Alcohol-based sanitizers are flammable. They should be stored in secure locations (out of reach of young children) away from extreme heat and ignition sources.  

In no way, hand sanitizer can be a substitute for good old handwashing with soap and water. Practice good handwashing technique, respect social distancing policies and refrain from touching your face. 

Be informed and don’t fall for marketing traps. Stay safe!

Additional resources:
CDC handwashing and hand sanitizer factsheet

When & How to Use Hand Sanitizer in Community Settings

WHO-recommended hand rub formulations

About the Author

Ameline Lim, Ph.D.
Ameline Lim, Ph.D., is a research scientist and biologist. She received her PhD from the University of New South Wales at Sydney, Australia. She has broad interests in medicine, history of science, and behavioural science. She is particularly interested in science education and the public understanding of scientific research. Her blog 'Science with Amy' celebrates the pleasures of finding things out and general curiosity.

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