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A well-maintained humidifier can ease the symptoms of asthma, allergies and the common cold. Extra humidity can also alleviate the effects of dry indoor air, such as dry nose, lips, skin and the throat, according to the United States Environmental Protection Agency's (EPA) website.

But a poorly maintained humidifier breeds mold and bacteria, which can worsen asthma and allergies or trigger lung infections, even if you're healthy. User documents for Vicks humidifiers, which include cool mist, warm mist, ultrasonic and UV models, closely echo the EPA's advice to clean your humidifiers regularly, although the EPA recommends cleaning a humidifier every three days, instead of the Vicks recommendation for weekly cleaning.


Switch off and unplug the humidifier before filling, cleaning or disinfecting it.

Insert a new filter or demineralization cartridge into the appropriate cavity, either in the top of your humidifier as for the V400, underneath the removable water container as for the V5100NS, or not at all as for the V745A.

Lift the water container straight out of the humidifier. In some cases the top section of the humidifier doubles as the water container. Turn the reservoir upside down, unscrew the cap, and fill to the fill line with cool tap water. If you live in a hard water area, using distilled water will cut down on the buildup of minerals inside your humidifier and the fine white powder these minerals produce when dispersed into the air.

Screw the cap back into the water container, turn it back right side up and insert it into the humidifier. Plug the humidifier in and turn the power switch on. Some Vicks humidifiers feature an additional intensity setting, either a high-low switch or a rotary knob that allows you to select the desired humidity level.

Check the water level in the humidifier once or twice a day if it is in near-constant use. Vicks humidifiers may run continuously for up to 20 hours after a single filling, depending on which model you use.


Wipe the outside of the humidifier and any non-submersible parts with a soft, dry cloth every day. Vicks recommends rinsing submersible parts with lukewarm water, then wiping clean and drying.

Wipe any parts of your humidifier that come into contact with water, except the nebulizer, with a soft cloth dipped in undiluted white vinegar once weekly. To the clean the nebulizer, soak it in a solution of one part white vinegar to one part water, then gently clean it with a cotton swab.

Soak the reservoir and pick-up tube, if present, in undiluted white vinegar for 20 minutes, swishing periodically. This loosens scale and other mineral buildup. Rinse clean, until all traces of scale have been removed. Wipe dry.

Disinfect your humidifier by soaking all submersible parts for 20 minutes in a solution of 1 tsp. bleach to one gallon of water. Shake or stir every few minutes. Rinse clean until all traces of bleach odor have dissipated.