Humidifiers (hue-MID-ih-fy-ers) add moisture to heated air. They can also work to protect your health. They are often used to combat dry throats and coughing, and doctors occasionally recommend their use for infants. If your home is heated with a forced warm-air system, a humidifier can be incorporated into the central heating system. Otherwise, portable one-room humidifiers are available. When purchasing a humidifier, look for one that drains completely on its own, because the models that drain partially into a separate pan will create a harbor for mildew and bacteria, causing allergic reactions in some people. Humidifiers are used only during the winter months because they operate in conjunction with the heating system. Heat drives out the moisture in the air, and the humidifier is used to put the moisture back. A humidifier would not be used with the air conditioner because the air conditioner takes moisture out of the air to cool it. Contact your local appliance dealer for more specific information on humidifiers.