Hand sanitizer is a liquid generally used to decrease infectious agents on the hands. Formulations of the alcohol-based type are preferable to hand washing with soap and water in most situations in the healthcare setting. It is generally more effective at killing microorganisms and better tolerated than soap and water. Hand washing should still be carried out if contamination can be seen or following the use of the toilet. They are available as liquids, gels, and foams. Alcohol-based versions typically contain some combination of isopropyl alcohol, ethanol (ethyl alcohol), or n-propanol. Versions that contain 60 to 95% alcohol are most effective. Care should be taken as they are flammable. Alcohol-based hand sanitizer works against a variety of microorganisms but not spores. Some versions contain compounds such as glycerol to prevent drying of the skin. Non-alcohol based versions may contain benzalkonium chloride or triclosan.