Q. With flu season and MRSA staph infection upon us, we are urged to wash our hands frequently, usually “with warm soapy water.” My memories of Bacteriology 101 some 50 years ago aren’t crystal clear, but I can’t recall that “warm” water kills anything. Soapsuds, on the other hand, do carry nasty things away. Is there any science behind the “warm water” suggestion?

A. You are absolutely right that warm water is no more effective than cold for removing germs. Soap and water don’t kill germs but only wash them off the surface of the skin.

If we had to guess, we would venture that it is far more pleasant to stick your hands in warm water than ice-cold water. The longer you wash and rinse, the more effective the process. Sing the alphabet song as you wash to get the timing right.

As it is, few people wash their hands as often as they should (after using the bathroom, before eating, after coughing or sneezing and so on).

This is a particularly serious problem in hospitals, where it is often difficult to get health care workers of all kinds to wash hands between patients. A worker who fails to wash can take germs from one patient and give them to the next.

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  1. J P
    Reply

    If bacteria and or a virus was put in cold water and left for a short period of time (say one minute) will the sample die?
    PEOPLE’S PHARMACY RESPONSE: NOT NECESSARILY. SOME BACTERIA AND MANY VIRUSES SURVIVE WELL IN WATER. BUT IF YOU HAVE RINSED IT OFF YOUR HANDS, YOU NO LONGER NEED TO WORRY ABOUT IT.

  2. JP
    Reply

    Question: Can cold actually kill germs and or a virus? For example, if someone put such a thing in your drinking water and it was very cold, would the water kill it?

  3. Ellen Lee
    Reply

    I saw a movie a couple of weeks ago. A woman and her small daughter went ahead of me into the ladies’ room on my way to the movie. I heard the little girl say to her mother, “We should wash our hands” when they exited the stall. The mother said, “We don’t have time”, and out the door they went. They sat in front of me, eating popcorn, during the movie. There is a real problem here!

  4. Jennifer Myers
    Reply

    The reason for using warm water is that warmer water dissolves soap more effectively. Since it is the soap that washes away the germs, the better the soap washes away, cleaner the hands.
    This is something anyone can demonstrate for himself. You can put equal sized bits of soap in cold, warm and hot water to see how much dissolves–or you can simply take a cold shower with plenty of soap involved. After such a shower, one has a slight but palpable soapy residue on the skin, and a definite soapy smell.

  5. Kelly C
    Reply

    Anybody who has ever washed a dish knows it’s easier to get them clean with warm water. Also, in the lab where I work, detergents are often used to lyse cells. I’m guessing that soap can kill some of the less hardy bacteria.

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