Humidifiers: How to Use and Maintain Them

Medically Reviewed by Jabeen Begum, MD on December 26, 2023
9 min read

Dry air may seem like a minor inconvenience, but it can significantly impact your daily comfort and health. Low humidity in your home affects moisture in your mucous membranes and skin. This dryness can cause you to experience bloody noses, dry eyes, itchy skin, and other unpleasant symptoms.

If you’re sick, you’ll feel the harmful effects of dry air even more. For example, harsh winter air can turn a mild cold or flu into a miserable ordeal as your cough worsens, your lips dry up, and your throat constantly feels scratchy. Dry air can also worsen allergies, asthma, and skin conditions.

A humidifier can help reduce these symptoms by putting moisture into the air.

Humidifier vs. vaporizer

A humidifier creates mist from cool water to spray into the air. A vaporizer heats the water until it's boiling and then releases that steam into the room.

Humidifier vs. air purifier

An air purifier helps improve indoor air quality. Many air purifiers draw air into the machine, where it passes through a filter where contaminants such as dust, pollen, and mold are removed. The air is then circulated back into the room. Some combination products have both an air purifier and a humidifier in one.

Humidifier vs. dehumidifier

The purpose of a dehumidifier is to remove moisture from the air. You may use one in your house if you live in a very humid area or have a damp basement. Dehumidifiers work by pulling air in and moving that air across a material or coil that dries it. As it dries, moisture is removed, and the air is returned back into the home. The processed air is about 50% less humid than when it went into the machine.

There are three different types of cool-mist humidifiers: ultrasonic, evaporative, and impeller. All of these use different mechanisms to release cool, humidified air into a room. These are safer for children's rooms because they don't have to be hot enough to boil water (like a vaporizer).


These humidifiers have an internal element that vibrates at a sound frequency that's outside the range of what people can hear (so they are named ultrasonic). This element moves so quickly that it creates water drops, which are then pushed into the air to increase the air's moisture level. One product that uses this technology is the rain cloud humidifier. Ultrasonic humidifiers are effective, quiet, and don't use a lot of energy.

One thing to consider if you are thinking about an ultrasonic humidifier is your pets. Sometimes, the sound can make dogs uncomfortable (even though humans can't hear it).


Impeller humidifiers have a disk made of small blades. The disk spins at high speed, making water droplets. The blades move the water through a mesh screen where the water is broken up and then pushed out through a nozzle, into the air.


Evaporative humidifiers use a fan to blow air over a wet, absorbent material such as a wick that sends moisture into the air. Not only is it simple and relatively safe, but it’s also less likely than other types of humidifiers to release bacteria and minerals into the air. But that’s only if you regularly clean it, dry it, and change the filters.


Central humidifiers are connected to your house’s plumbing as well as heating and air conditioning, and they cover the entire house. It’s convenient because you don’t have to refill the water supply, but you do need to maintain the system well to keep certain allergens from getting into the air.

Steam vaporizers

Vaporizers work the same way as a pot of water on the stove. They boil water to make steam, and it evaporates into the air. Some doctors warn against using these if you have children because of the risk of burns.

Dry, cold air can cause all kinds of problems with your sinuses and throat. Parched air draws fluid from your sinuses, which can make you more likely to have nosebleeds or sinus infections. Besides helping prevent those things, a humidifier also may make it easier to breathe if you have a cold or another condition that affects your lungs.

Humidifiers may also help with the following:

  • Calm and reduce a cough
  • Loosen mucus in your chest so you can expel it more easily
  • Maintain pets’ body temperature during general anesthesia in veterinary settings
  • Reduce stuffiness caused by the common cold and other respiratory conditions
  • Soothe a sore throat

If you have dry skin, dry eyes, and other irritations from dry air, a humidifier can ease these symptoms. Even if you don’t have problems with your nose, throat, or skin, you may find dry air to be unpleasant. A humidifier may give you a sense of comfort.

Humidifier for babies

Putting a humidifier in your baby's room could help your little one's dry sinuses and skin. The soft humming can also help your baby sleep better. But talk with your doctor before putting a humidifier in an infant's room. They get moldy easily if not cleaned well, and they can circulate that mold and bacteria back into the room, potentially causing harm to your baby's lungs. If your doctor recommends a humidifier for your baby's room, be sure to:

  • Keep it on a high shelf away from where your baby sleeps.
  • Check it regularly for mold or white dust.
  • Clean it at least every few days.
  • Fill it with distilled water.
  • Use a cool-mist humidifier.
  • Measure the room's humidity to make sure it doesn't get too damp and grow mold on the walls or ceilings.
  • Avoid scented oils or other additives.

Humidifier for asthma

Humidifiers haven't been proven to be an effective treatment for asthma. In fact, if humid air triggers your symptoms, you want to avoid humidifiers. If your symptoms worsen in cold, dry air, which is common for some people with asthma, a humidifier may reduce the number of asthma attacks you have. If you do want to use a humidifier, be sure to maintain and clean it regularly, so you don't inhale mold and bacteria trapped in the machine. This can worsen your symptoms. Clean it frequently, use distilled water to reduce mineral buildup, and make sure to replace filters or other components according to the manufacturer's instructions.

Humidifier for sleep

Using a humidifier at night may help reduce the discomfort that comes with a dry bedroom. Here are various ways a humidifier can help:

  • Unclogging a stuffy nose and making it easier to release mucus when you have a cold
  • Easing breathing issues if you have bronchitis
  • Soothing dry skin
  • Reducing nosebleeds related to dry sinuses
  • Creating white noise, which can help some people sleep better
  • Relieving the dry skin, nose, and mouth, which are a result of using a continuous positive airway pressure (CPAP) machine

You should put your humidifier about 6 feet away from your bed in a place where air circulates well.

Humidifier for cough 

Increasing the amount of humidity in the air can help soothe a sore throat and relieve your cough. Moisture in the air may also help break up chest congestion, making it easier to cough up and get rid of mucus.

Humidifier for allergies

Talk to your doctor before using a humidifier to relieve your allergy symptoms. A cool-mist humidifier may improve some of your symptoms, but if you don't clean the machine regularly, mold can grow in it and get carried into the air, which could make your allergies worse. Too much humidity in a room can also cause mold growth, which can worsen your symptoms.

What are other common humidifier uses?

  • Helping humidity-loving houseplants thrive
  • Preventing your floorboards, furniture joints, and other wood from drying out
  • Reducing irritation in your eyes, lungs, throat, and mucus membranes

Tap water has different amounts of minerals, depending on where you live. These can gum up your humidifier and breed bacteria that get spewed into the air along with water vapor. The minerals also can form a fine white powder that can lead to crusty deposits in the machine, which is another breeding ground for bacteria. These issues are more common with ultrasonic and impeller humidifiers.

Distilled water, available in grocery stores, has fewer minerals, but it’s not clear that it’s any better than tap water as long as you clean your humidifier regularly.

The humidity level in your home needs to be 30%-50%. Humidity that is too low can cause dry skin and eyes, static electricity, and cold-like symptoms such as sore throat and cough. If humidity is too high, the vapor in the air becomes water droplets, settling onto walls, floors, and furniture. These wet conditions can cause the growth of mold and bacteria in your house.

You can measure the moisture in your home's air with a tool called a hygrometer, which you can find at most hardware stores. Some humidifiers, called humidistats, have built-in hygrometers. A humidistat will track the moisture level in your room and make sure it stays in the 30%-50% range.

Humidifiers can be hard to set up and use. Because they retain water to add moisture to the air, you'll need to clean the machine regularly to prevent mold growth. If you get respiratory symptoms, including a flu-like feeling, fever, cough, or difficulty breathing, after starting the use of a humidifier, turn it off and call your doctor.

 If you use a humidifier improperly, this machine can have several negative effects:

  • Excess humidity can make allergies and asthma worse.
  • Humidifiers kept in a small space can cause excess condensation, leading to the growth of bacteria and mold. 
  • If you don’t clean your humidifier frequently, mold can also grow inside the machine before being blown around the house.

Humidifiers that use ultrasound technology leave a fine white dust, which can build up in your house over time. This is due to the minerals in tap water that are filtered and released back into the air. This is more likely to happen if you live in an area that has very hard water. Using distilled water in your unit reduces the amount of dust that collects as a result of humidifying.

While humidifiers can be helpful in lots of ways, it’s important to keep them clean and well-maintained. A dirty humidifier can be a breeding ground for bacteria and mold, which can get sent out into the air where you can breathe them in. The same goes for the tiny minerals in bottled or tap water.

And don’t let the air get too humid as it can lead to condensation on walls and floors, providing a home for bacteria, mold, and dust mites. These can trigger allergies and be especially harmful if you have problems with your breathing, such as asthma. An air conditioner or dehumidifier can help even humidity out.

The device manufacturer should offer instructions on keeping your humidifier clean and mold-free. You may also want to follow these steps:

  • Always unplug your humidifier before you clean it. Water and electricity can be dangerous together.

  • Change the water daily and rinse and dry the base and tank every day.

  • Every 3 days, get rid of any mineral buildup with vinegar, hydrogen peroxide, or another solution suggested by the manufacturer. If the manual for your model calls for it, disinfect the humidifier with a 10% bleach solution or any other disinfectant. Be sure to rinse the tank with several changes of water if you use bleach or any other cleaning chemicals so the machine doesn’t put them into the air next time you use it.

  • Check your filters or cartridges regularly, and change them according to the manufacturer's instructions, or more frequently if needed.

  • When it's time to store your humidifier, clean it before putting it away. When you get it out again, clean it well and replace any old filters or cartridges.

  • If your humidifier is getting old and there is a buildup of minerals that can't be removed, it's time to replace it.