Hand Sanitizers: Are They Really Worth It?

By Aayesha Siddiqui (@aayesha)
CommonHealth Contributor

Last week I posted about norovius, a common and contagious virus that sends people scurrying for the bathroom. One of the take home lessons was the importance of routinely washing your hands, whether you’re sick or healthy.

But then came the inevitable question: What about hand sanitizers? Won’t they work?

You’ll find wall dispensers full of alcohol-based liquids, gels, and foams outside elevators, in public bathrooms, all around the hospital even. Parents send their kids to school with mini-bottles of the stuff. One of our readers commented, “I keep one in my car to apply after being in public places like stores and supermarkets…thought I was getting rid of the germs.”

Our reader is getting rid of a lot of germs—but not all of them.

The Science Behind the Sanitizer

If you look at the active ingredient on the back label of your hand sanitizer, you’ll most likely find it’s ethyl alcohol (a.k.a. ethanol, the same alcohol that’s in your glass of wine or in your spray of perfume) or isopropyl alcohol (a.k.a. isopropanol, but you probably know it as rubbing alcohol). The bottle should also say that it’s between 60% to 95% alcohol (the concentration that’s most effective in killing off most germs).

So, how does the alcohol actually work? Think of a germ as having a well manicured hair-do. Every strand of hair is styled in a very particular way, and the whole hair-do only works if every strand holds its individual structure. But then the germ steps outside into an especially humid summer day. Its hair-do gets assaulted by the heavy, sticky air; the strands end up going limp, losing their original shape. Goodbye, perfect hair-do.

The germ’s proteins (essential to its life processes) are like its strands of hair, and alcohol is like the humid weather. The alcohol denatures the proteins, causing them to lose their structure, rendering them useless. Goodbye, viable germ.

Why Sanitizer Is Not a Silver Bullet

It sounds like alcohol is pretty powerful, right? Well, there are a few things to consider.

First, consider the pathogen and what kinds of germs are you actually trying to get rid of.

Alcohol-based sanitizers, at the concentrations commercially available, work best against bacteria (like E. coli or salmonella), fungi, and certain types of viruses (enveloped viruses—viruses that have a coat around them, like the influenza virus and HIV). Check, check, and check.

But what about non-enveloped viruses (like norovirus or rotavirus)? Alcohol-based hand sanitizers have been shown to have some effect—with ethanol doing better than isopropanol—but their killing prowess here isn’t as strong as against the other germs. Sanitizers also won’t do much good against protozoa (like what causes malaria) or bacterial spores (like those of C. difficile). (If you want to geek out on the scientific literature, take a look at the World Health Organization Guidelines on Hand Hygiene in Health Care, starting on page 32.)

Take home lesson: It doesn’t hurt to use hand sanitizers, just know that you’re not fully protected.


A key question is: How long will your hands remain free of germs after using the sanitizer?

You rub your hands and the germs start dying off, and the ones that remain even take a bit longer to grow back than usual. Win-win. But that doesn’t mean that the effect persists. You’ll need to re-apply hand sanitizer after you come in contact with a contaminated surface, a sick person, or anything else that might be germ-laden.

Take home lesson: Hand sanitizers are quick-acting, but not long-lasting.

Personal Error

The research that’s been done on the germicidal powers of alcohol has been done both in the lab (in vitro) and in real life with real people (in vivo). These are, of course, two very different settings. Exposing germs to alcohol in the lab is far more uniform than when someone takes a squirt of sanitizer from the hallway dispenser and hurriedly rubs her hands together on her way to wherever she’s going. Or, perhaps her hands are visibly dirty and she doesn’t have time to run to the bathroom—maybe hand sanitizer can act as a stand-in?

The Centers for Disease Control and Prevention caution against this. They emphasize that visibly soiled or dirty hands reduce the efficacy of alcohol-based hand sanitizers. You should therefore wash your hands if there’s anything on them. Using a hand sanitizer can be effective if you have visibly clean hands, but you’ll need to make sure to correctly rub the sanitizer on so it can actually work its magic.

Take home lesson: If you’re going to use sanitizer, make sure your hands are not visibly dirty.

Hypochondria Mania?

All this talk of sanitizers had me questioning everything I touched. I admit: I too carry a travel-sized bottle in my backpack. I reach for it before I touch public keyboards, after I use public transportation—even sometimes after shaking hands. Am I overreacting? Maybe.

The truth of the matter is alcohol-based sanitizers are useful, convenient, and effective in most circumstances. But they aren’t a cure-all. If you want your bases covered, wash your hands routinely and supplement with alcohol-based sanitizers. And don’t be shy—scrub and rub vigorously. Better safe than sick in the bathroom.

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  • Jesse

    A much-needed article – more than 50% of Americans think alcohol sanitizers last longer than 15 seconds. One study out of Emory showed that it was actually more effective to just rinse your hands with plain water than use an alcohol sanitizer against the Norovirus. However, there are some great alternatives out there, and I wish the author had explored other options. One that I’ve come across is the Zylast products. The company has posted studies showing it kills 99.97% of the Norovirus on contact – more than 100 times more than alcohol and handwashing – and it’s persistent. When it was used in a school, where viruses are a major cause of illness, it was shown to reduce illness by 41.6% among students and 24.7% among teachers and staff. And it’s water-based, non-flammable, and actually moisturizes the hands – worth giving it a try if you’re fed up with your alcohol sanitizer. http://www.Zylast.com

  • lay

    im in middle school is this article wrong?

  • lay

    thank you this helped a lot

  • Concord

    I believe the article is meant for public education, not for journalistic competition.  Obviously Educational Psychology was applied in this article for   EFFECTIVE   public education. 

  • Concord

    I believe the article is meant for public education, not for journalistic competition.  Obviously Educational Psychology was applied in this article for   EFFECTIVE   public education. 

  • Concord

    I believe the article is meant for public education, not for journalistic competition.  Obviously Educational Psychology was applied in this article for   EFFECTIVE   public education. 

  • Concord

    You have no idea how many healthcare workers count on a hand sanitizer, thinking it’s good enough to protect the next patient from the bug collected from the patient before.  This article serves as a helpful warning, not only to healthcare providers but for everyone in society that fall prey to the profiting hand sanitizer manufacturers.   Proper handwashing can never be over-emphasized to a pathogen-laden society , in which a good percentage has poor health habits.  

  • http://twitter.com/Rwilsker Roy Wilsker

    This would be a more useful article if it provided some general information on the general distribution of the various pathogens – not to a super techie degree, but just general rules of thumb. Ok – hand sanitizers don’t do much about rotaviruses. But what’s the relative likelihood of encountering a rotavirus versus a bacterial pathogen?

    To take it to an extreme – I doubt hand sanitizers protect me from unicorns that fall from the sky. Should that make me worried? Don’t think so – not a real likely event.

    A little math goes a long way.

  • Oh Please

    This is a very badly written article — full of buzzspeak, meaningless “win-win” garbage, talking down to the readers like they’re all a bunch of retarded people. Fire this writer.

    • Why

      Says the person who doesn’t know the difference between action verbs and linking verbs hence using the word “badly” incorrectly. Also, if you wanna make a point, try not to use “retarded” derogatorily.