Hand sanitizer (also known as hand antiseptic, hand disinfectant, hand rub, or handrub) is a liquid, gel or foam generally used to kill many viruses/bacteria/microorganisms on the hands. In most settings, hand washing with soap and water is generally preferred. Hand sanitizer is less effective at killing certain kinds of germs, such as norovirus and Clostridium difficile, and unlike hand washing, it cannot physically remove harmful chemicals. People may incorrectly wipe off hand sanitizer before it has dried, and some are less effective because their alcohol concentrations are too low. Alcohol-based hand sanitizer that is at least 60% (v/v) alcohol in water (specifically, ethanol or isopropyl alcohol/isopropanol (rubbing alcohol)) is recommended by the United States Centers for Disease Control and Prevention (CDC), but only if soap and water are not available. The CDC recommends the following steps when using an alcohol-based hand sanitizer: Apply product to the palm of one hand. Rub hands together. Rub the product over all surfaces of hands and fingers until hands are dry. Do not go near flame or gas burner or any burning object during application of hand sanitizer. In most healthcare settings, alcohol-based hand sanitizers are preferable to hand washing with soap and water, because it may be better tolerated and is more effective at reducing bacteria. Hand washing with soap and water, however, should be carried out if contamination can be seen, or following the use of the toilet. The general use of non-alcohol-based hand sanitizers is not recommended. Alcohol-based versions typically contain some combination of isopropyl alcohol, ethanol (ethyl alcohol), or n-propanol, with versions containing 60% to 95% alcohol the most effective. Care should be taken as they are flammable. Alcohol-based hand sanitizer works against a wide variety of microorganisms but not spores. Compounds such as glycerol may be added to prevent drying of the skin. Some versions contain fragrances; however, these are discouraged due to the risk of allergic reactions. Non-alcohol based versions typically contain benzalkonium chloride or triclosan; but are less effective than alcohol-based ones. Alcohol has been used as an antiseptic at least as early as 1363 with evidence to support its use becoming available in the late 1800s. Alcohol-based hand sanitizer has been commonly used in Europe since at least the 1980s. The alcohol-based version is on the World Health Organization's List of Essential Medicines. History Uses General public Alcohol-based hand sanitizers may not be effective if