Humidifier therapy adds moisture to the air. This can help prevent dryness that can cause irritation. But if not cleaned properly, humidifiers may spread bacteria and lead to illness.

Humidifiers are devices that add moisture to the air to prevent dryness that can cause irritation in many parts of the body.

Humidifiers can be particularly effective for treating dryness of the skin, nose, throat, and lips. They can also ease some symptoms caused by the flu or common cold.

But overusing humidifiers or not cleaning humidifiers properly can potentially worsen respiratory problems and cause other health conditions.

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Humidity acts as a natural moisturizing agent that can relieve dryness, especially when it’s cold outdoors when the air is dryer. For this reason, humidifiers are often used to relieve:

  • dry skin
  • sinus congestion/headache
  • dry throat
  • nose irritation
  • bloody noses
  • irritated vocal cords
  • dry cough
  • cracked lips

You may be prone to these discomforts when the air in your home is dry. This is especially common during winter months or when an air conditioner is being used during the summer.

Some people may also use humidifiers to relieve symptoms related to health conditions. These may include:

The type of humidifier you choose depends on your preferences, budget, and the size of the area you want to add moisture to. The five types of humidifiers include:

  • central humidifiers
  • evaporators
  • impeller humidifiers
  • steam vaporizers
  • ultrasonic humidifiers

Humidifier sizes

Humidifiers are often classified as console or portable/personal.

Console units are meant to add moisture to the entire house. They’re often very large but usually have wheels, so you can easily move them around. Console units are meant to add moisture to one room.

Personal (or portable) humidifiers are the smallest and are the best choice if you need a humidifier while traveling.

Discover the best humidifiers in both sizes.

Central humidifiers

Central humidifiers are built directly into your home’s air conditioning or heating unit. These are the most expensive types of humidifiers, but they’re the best choice if you want to add humidity throughout the entire house.

Traditional humidifiers carry a potential risk of burns from the steam they emit. Central humidifiers don’t emit steam.

You may already have one attached to your home’s heating and cooling system. If not, a heating, ventilation, and air conditioning (HVAC) specialist may be able to install one.

You may need to replace the filter once per year or up to once every 3 months, depending on how often it’s used, as well as the make and model.


Evaporators blow moisture through a moistened filter. Fans power the unit and expel humidity into the air from a single-unit system.

These are more affordable than central humidifiers, but the downside is that they only work in one room at a time. They may also expel too much moisture into the air. This can be problematic for people with asthma, as it raises the likelihood of mold growth.

Impeller humidifiers

Impeller humidifiers work with the help of rotating disks that run at high speeds. These units are often less expensive. They’re also among the most child-friendly devices because they create cool mist and carry no risk of burns.

The downside is, like evaporators, they only work for single rooms. They can potentially cause breathing difficulties for people with allergies and asthma when they’re overused.

Steam vaporizers

Steam vaporizers are electrically powered. They heat water and then cool it before expelling it into the air. These are the most inexpensive and portable humidifiers. You can purchase them at drugstores.

This type can cause burns, so it’s not the most kid-friendly.

Learn more about vaporizers.

Ultrasonic humidifiers

Ultrasonic humidifiers produce a cool mist with the help of ultrasonic vibration. The units vary in price, depending on the size you need for your home. Both cool and warm mist versions are available.

An ultrasonic humidifier — especially the cool-mist version — is a good choice if you have children.

Adding humidity to the air may be beneficial, but too much humidity can cause health issues. High humidity levels can worsen respiratory problems and create uncomfortable dampness in the air. This can encourage the growth of:

  • dust mites
  • mildew
  • mold
  • harmful bacteria

Keep the humidity between 30 and 50%. A hygrometer can determine how much humidity is in your home. Some central humidifiers come equipped with hygrometers, but you can also find them at hardware stores.

Test the humidity daily, especially if someone in your household has allergies or asthma.

Burns are the most common injuries associated with humidifiers. Take special care if you have children. Never let children handle humidifiers, and don’t place a warm-mist steamer in a child’s bedroom.

Allowing a unit to expel too much moisture can create condensation on the walls. If you place the humidifier too close to fabric, like beds, sofas, or drapes, these items can become damp. As a result, mold can grow and spread throughout the home.

Unclean humidifiers can cause bacterial growth that can promote coughs and colds, according to a 2022 study.

Steam vaporizers can get dirty quickly, but they’re also among the easiest to clean. Rinse out all the used water between uses. Some humidifiers should also be left to dry out between uses.

Following the manufacturer’s instructions, clean the unit regularly to prevent bacterial growth. Wash the bucket and filter system every 2 to 3 days during use.

Humidifiers can potentially emit minerals and microorganisms. They’re not necessarily harmful, but the residue can bother people with asthma. Use distilled water rather than tap water to avoid this problem.

Before storing the humidifier, make sure all the parts are dry to prevent mold from growing.

Learn how to clean a humidifier.

When used with care, humidifiers can make a significant difference when it comes to dry skin and airways. But keep in mind that this is a home remedy — not a medical treatment.

Stop using a humidifier and call your doctor if you have symptoms that don’t improve or seem to be getting worse because of the humidifier.