Do hand sanitizers really work?

October 14th, 2009

Professor James Scott is an associate professor in the Division of Occupational & Environmental Health at the Dalla Lana School of Public Health. He is cross-appointed to the Department of Medicine, Division of Clinical Pharmacology and Toxicology, and holds hospital appointments at St. Michael’s Hospital and the Hospital for Sick Kids.

Does hand sanitizer work?

I was one of the skeptics. But as I have looked critically at the research that has come out, I can say yes, it really works. It works exceedingly well. It reduces the skin burden of bacteria much more effectively than soap and water and the amount of bacteria on the skin tends to remain lower for much longer than when soap and water is used. It also tends to be less damaging to skin because it has built-in emollients. People who are in occupations where there is a lot of hand washing, have skin that tends to dry out easily and it can crack and become more prone to carrying bacteria.

How does it work?

It works by killing cells—not human cells. It kills microbial cells. It’s based on the use of 70 per cent isopropanol alcohol, which is rubbing alcohol.  That’s the concentration of rubbing alcohol that is most effective in killing germs—it’s even more effective than 100 per cent. Because it has a little bit of water in it, it improves penetration. For a virus, sanitizers work by disrupting the virus’s outer coat. For a bacterium, they work by disrupting its cell membrane.

Some people say that using hand sanitizer is bad because it prevents us from building up natural resistance to bugs.

Show me the evidence.

Physicians used to tell their patients if they didn’t want their kids to be allergic to cats, then don’t have a cat. Physicians have told their patients this for the last 50 years. Now there’s growing evidence that if you have the cat, you might actually have some protection against allergies. What you’re saying is a similar idea. But the reality is we just don’t have that information. There’s no evidence to support it one way or another.

So for things like H1N1 you recommend people use hand sanitizer.

This is the absolute best front-line protection for those kinds of diseases.

Is it only colds and flus that hand sanitizers fight?

They work on a range of bacterial and viral illness. Depending on what the agent is, it may be more or less tolerant or susceptible to these hand sanitizers, but for most of the things that people need to worry about in day-to-day life—upper respiratory infections, gastrointestinal infections, those kinds of things—most agents that cause those diseases are highly susceptible to modern hand sanitizers.

What about health care workers? How much does our health depend on them using these products?

In occupations where there’s a lot of human contact there’s the potential for the practitioner to act as an intermediary, transferring germs from one patient to the next. Anything that’s effective and increases the compliance of the practitioner in going through the motions of infection control and prevention is helpful.

There have always been difficulties with compliance, getting health care workers to wash hands on a sufficiently frequent basis, between patients and between tasks. Compliance was always difficult because handwashing is often inconvenient and takes time. The introduction of hand sanitizers improved hand hygiene tremendously, not only because it was so effective, but it was also easier and faster than regular handwashing. It’s really helped in terms of reducing germ transmission. It’s often cited as an example of an improved infection control measure that is a runaway success on all fronts.

So you’re not a skeptic any longer.

No. In the past several years, as I’ve seen evidence build up, I’ve ceased to be a skeptic. This stuff really does work. I doubted it, but it works.

Hand santizing station. Source Flickr, photo by John Kannenberg


16 responses to “Do hand sanitizers really work?”

  1. M.Mendel Bocknek, MD says:

    we in the medical profession need to get this out there NOW….perhaps you have enough influence to get this on FOX TV Cable Sunday am ‘House Call’ w/ Dr.Isadore Rosenfeld….
    Dr.M.M.Bocknek, Meds U/T 1954.

  2. TS says:

    I’m no expert on this, but I find it very interesting.But I wonder: what are the chances of hand sanitizers adding to the problem of anti-microbial resistance?

  3. John Murphy says:

    While its true there’s abundant information on germicidal efficacy, I’m unaware of any evidence that use actually reduces risk of influenza transmission. Influenza A on the hands doesn’t equate to getting sick, and its absence on the hands doesn’t equate to being protected. If I’m missing some key evidence to the contrary I’d welcome correction.

  4. James Scott says:

    Yes, alcohol-based hand sanitizers are effective against flu viruses (Clin Inf Dis 48: 285-291, 2009). The extent to which this reduces transmission is uncertain, but many experts are in agreement that on the balance of probability and based on the precautionary principle, hand hygiene is a worthy component of a flu infection control program (e.g.

  5. Noemi says:

    How often I have to wash my hand with sanitizer to prevent any ills.
    In my country, we have swine flu epidemic.

  6. shweta says:

    see H1N1 is a viral infection which spreads through air and hand sanitizer is used to clean hands. this infection will spread through air like cough, sneeze etc. how will sanitizer then help you stay away from it.please help!!

  7. Lancks says:

    Hand sanatizer such as this won’t encourage ‘super-bugs’, as alcohol physically breaks down the bugs. It doesn’t poison them (leaving a few behind to become poison-resistant).

  8. Dr. Grant Merritt says:

    Dr. Scott’s opinions are very interesting but I have done PubMed searches and don’t find the research to back up his claims. Yes, alcohol based sanitizers work well on clean, inantimate surfaces, (that’s where most of the studies have been performed), but I can’t find any reputable research that shows that they work any better than soap and water on human skin. The problem with the general public is that they are not washing their hands several times an hour and the bio-burden on a runny-nosed little kid’ hands will quickly render the gels and foams ineffective. Of course if we’re to uncaring or too lazy to wash our hands at least they may smell better.

  9. Shweta – there is strong suggestion that H1N1 is not like other flu viruses in that it can be transmitted by contact as well as aerosols.

    Dr. Merritt, a pubmed search using “hand sanitizer” or “hand hygiene” as a keyword terms will not reach much of the relevant literature. I suggest you start by reading the very comprehensive review given in chapter 96 (pp 1727-1746) of Hospital Epidemiology and Infection Control, 2nd edition.

  10. tracey says:

    Thats all well and good but the stuff is not so much fun when you have a twelve year old girl who gets a headache, light headed and vomits everytime someone uses it around her and the government decices it has to be in every school for the children to stay safe!
    Wonder if anyone has any information to help my daughter avoid this stuff when she has it in her school.

  11. Kevin says:

    While the alcohol based foam is effective and we have very good compliance of use by all caregivers, they have very dry hands.
    So they bring in their favorite hand lotion to use. A consultant now says we must ban all hand lotion EXCEPT on type because the lotion renders the alcohol based foam sanitizer ineffective. This makes no sense to me and I cannot find the resarch either way. Any suggestions?

  12. Luke Chapman says:

    An interesting article and some interesting responses too. I’ve recently taken on a new range of sanitisers and was searching the internet to get a bit of background information. Unlike alcohol based hand sanitisers this range works at a molecular level, targeting the bacteria, viruses and fungi themselves, leaving the environment or surface unaffected. In doing this it builds a residual barrier on the surface that goes on protecting against re-contamination, unlike alcohol based sanitisers that are only effective when wet. This barrier has been proven to stay effective over 30 days in clinical trials. I’d like to get your thoughts and views on the range and possible comparissons against the alcohol based sanitising products that you’ve been discussing. I’m not sure if I can post links here so please search RBT 24/7 for full information.

  13. T Peacock says:

    Unfortunately this bald statement of Prof Scott lacks the limitations needed to qualify such a statement. As the Mayo Clinic clearly points out, ALCOHOL BASED hand sanitzers work. There is enough research available which clearly states that non-alcohol based hand sanitizers DO NOT work.

  14. HLS says:


  15. JJL says:

    ^^^ LOL.

  16. brittany says:

    i love hand sanitizer soooooooooooooooooooooooooo much i use it every day of my life goooooooooooooooooooooooooooooo hand sanitizer