Choosing a Cool Mist or Warm Mist Humidifier

The difference between these types of humidifier

A humidifier can be a useful addition to your home, but how do you know if you need a cool-mist humidifier or a warm mist humidifier?

This article will compare cool mist humidifiers vs. warm mist humidifiers, including what each type of humidifier is most useful for.

Sick woman on the couch with a humidifier
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Cool Mist vs. Warm Mist Humidifiers

Cool mist humidifiers and warm mist humidifiers both add moisture to the air which moistens your skin (including your nasal passages) and thin mucus in your sinuses. The National Institutes of Health recommends the use of humidifiers to help relieve congestion from the common cold, flu, and sinus infections. Using a humidifier makes it easier for you to breathe and makes it easier for the mucus to drain.

The key is to keep your humidifier clean and properly maintained so you don't create an environment that keeps you sick, rather than helping you get better.

There are two main categories of humidifiers: warm mist and cool mist. They essentially do the same thing but in different ways. When comparing cool mist humidifiers vs. warm mist humidifiers, you'll find that each has pros and cons to consider.

Cool Mist Humidifiers

Cool mist humidifiers are an effective way to humidify your home and relieve congestion, dry throats, and skin. There are three types of cool mist humidifiers.

  1. Impeller: Uses a high-speed rotating disk to release water droplets into the air
  2. Evaporative: Transmits moisture into the air using a fan, which blows through an absorbent material
  3. Ultrasonic: Creates a cool mist by means of ultrasonic vibrations.

The American Academy of Pediatrics recommends the use of cool mist humidifiers for children, though this advice could also apply to adults. There is a risk of burns when using warm mist humidifiers or steam vaporizers.

Although cool mist humidifiers do not have the danger of burns or fire hazards, there are concerns with these devices as well. If not properly cared for, cool mist humidifiers can harbor bacteria, mold, and mineral deposits, which they release into the air.

It is very important to properly clean your humidifier according to the manufacturer's instructions.

Other ways to ensure that you are not putting yourself and your family at risk using a humidifier include:

  • Changing the water in the holding tank every day
  • Thoroughly cleaning the entire humidifier every three days
  • Using distilled water in the tank rather than mineral-filled tap water

Monitoring Your Home's Humidity Levels

It will be helpful to monitor the humidity level in your home. The devices that do this are called hygrometers and are available at hardware stores to use in your home.

The ideal humidity level in your home should be somewhere between 30% to 50%. Humidity levels higher than 60% encourage the growth of bacteria, mildew, mold, and fungi.

Warm Mist Humidifiers and Steam Vaporizers

If you prefer to use a warm mist humidifier and do not have young children or people in your home that are at high risk for burns from them, you still need to properly care for your humidifier and follow all safety precautions.

Steam vaporizers and warm mist humidifiers both heat water and then release it into the air. Warm mist humidifiers and steam vaporizers are effective ways to relieve congestion but should be used with care. Both have heating elements that can cause burns and can even be a fire hazard.

Follow these guidelines to safely use a warm mist humidifier or steam vaporizer:

  • Keep them out of the reach of children and away from flammable objects
  • Never place a warm mist humidifier or steam vaporizer on the carpet or another upholstered surface
  • Do not add oils or “vapor rubs” to the humidifier
  • Use distilled water instead of tap water
  • As with cool mist humidifiers, always follow the manufacturer's instructions for care and use, including keeping it clean


The best humidifier for you and your home will depend on your needs. When you’re comparing cool mist humidifiers vs. warm mist humidifiers, you’ll find that while they have similar functions, each one offers its own benefits for managing certain health conditions or symptoms. No matter which humidifier you choose, make sure to read the directions and follow the instructions for safe use.

Frequently Asked Questions

  • Is a cool mist humidifier or warm mist humidifier better for allergies?

    Warm mist humidifiers tend to work well for easing symptoms like congestion that come with a cold or allergies. However, if you have a child at home, it’s safer to use a cool-mist humidifier. While they might not be as effective, they don’t have hot water that can cause burns.

    It’s also important to keep in mind that sometimes, a humidifier can make certain allergies worse—for example, a moist environment in your home can contribute to mold growth.

  • Is a cool mist humidifier or warm mist humidifier better for asthma?

    Humidifiers may ease asthma symptoms but they can also make it harder for you to breathe. Experts don’t agree on whether cold mist or warm mist humidifiers are better for everyone with asthma. You’ll need to try both and see which one helps your symptoms the most and is the safest option for your home.

    Whichever humidifier you choose, keeping it clean is very important. Mold and other contaminants from a dirty humidifier can make your asthma worse.

5 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Lau CJ, Loebel Roson M, Klimchuk KM, Gautam T, Zhao B, Zhao R. Particulate matter emitted from ultrasonic humidifiers—chemical composition and implication to indoor air. Indoor Air. 2021;31(3):769-782. doi:10.1111/ina.12765

  2. American Academy of Pediatrics. Caring for your child’s cold or flu.

  3. Children’s Hospital Colorado. The hidden danger of humidifiers.

  4. American Academy of Allergy, Asthma, & Immunology. Humidifiers and indoor allergies.

  5. Allergy & Asthma Network. What you need to know about humidifiers and sinus troubles.

By Kristina Duda, RN
Kristina Duda, BSN, RN, CPN, has been working in healthcare since 2002. She specializes in pediatrics and disease and infection prevention.