Cool Mist vs. Warm Mist Humidifiers: What Experts Say

For people who experience uncomfortable symptoms like sinus irritation, dry throat, nasal congestion, and dry skin, a humidifier can be a game-changer. These accessible devices can help ease symptoms of colds, asthma, and allergies. We asked experts to explain the differences between cool mist vs. warm mist humidifiers.

“A humidifier can help if there’s dryness in the air and that dryness is a trigger. For example for some, dry air can make their asthma and sinus/allergies worse, whereas for some, humidity can trigger it. This can be helpful in winter when heaters make the air more dry,” explains Purvi Parikh, M.D., an allergist at Allergy and Asthma Associates of Murray Hill

Meet the experts: Timothy Ryan, M.D., lead otolaryngologist at Wellstar Health System; Purvi Parikh, M.D., an allergist at Allergy and Asthma Associates of Murray Hill; and Michael Yong, M.D., otolaryngologist and fellowship-trained neuro-rhinologist at Pacific Neuroscience Institute

There are two types of humidifiers: Cool mist and warm mist. And while the type you choose ultimately comes down to personal preference, according to Michael Yong, M.D., board-certified otolaryngologist (ENT) and fellowship-trained neuro-rhinologist at Pacific Neuroscience Institute, “there are some different features of warm and cool mist humidifiers which may or may not be better for things independent of nasal symptoms,” including safety, noise, and more.

“Cleaning is the biggest thing missed,” says Timothy Ryan, M.D., lead otolaryngologist at Wellstar Health System. “A dirty humidifier can aerosolize mold, bacteria, and mineral particles into the air. The best humidifier is the one that’s cleaned regularly and keeps indoor humidity between 30% and 50%.”

Below, experts explain key differences between cool mist and warm mist humidifiers.

Most of the humidifiers you’ll find on the market today are cool mist humidifiers, which have a few different ways of operating, but in general are the safest option (especially if you have children or pets around), according to the U.S. National Library of Medicine.

Below, experts break down the pros and cons of cool mist humidifiers.

Cool mist humidifier pros

• May help calm coughs and other cold symptoms
• May slightly cool the overall room temperature
• Considered the safest to use around children and pets. “Most pediatricians prefer cool-mist humidifiers because they provide the same humidity benefit without the risk of burns from hot water or steam,” explains Dr. Ryan.

Cool mist humidifier cons

• May be noisier than warm mist humidifiers
• May harbor and dispense mold, dust mites, and bacteria if not cleaned properly

Types of cool mist humidifiers

Dr. Yong explains that cool mist humidifiers can work in two different ways:

• Evaporative cool mist humidifiers. These humidifiers use a fan to add moisture to the air.
• Ultrasonic cool mist humidifiers. Using physical sonic energy or vibrational sound energy, Dr. Yong notes, these humidifiers produce a cool mist that adds moisture to the air.

Warm mist humidifiers, also known as vaporizers, use electricity to heat water inside the tank and produce a warm mist to add moisture to the air. According to the United States Environmental Protection Agency (EPA), these humidifiers pose a lesser threat of dispersing bacteria into the air. However, they are generally not recommended for use around children and pets as the hot water and steam can be a safety risk.

“Warm mist can feel more soothing and may help nasal congestion from colds, thick mucus, postnasal drip, sore throat, laryngitis/voice strain, and dry coughs,” says Dr. Ryan.

Below, experts share the pros and cons of warm mist humidifiers.

Warm mist humidifier pros

• May help elevate the overall room temperature in colder months
• Are often quieter than cool mist humidifiers
• Pose a lesser threat of dispensing allergens and bacteria into the air
• Helps soothe nasal passageways.

Warm mist humidifier cons

• Not recommended for use around children and pets

Types of warm mist humidifiers

When it comes to warm mist humidifiers, they most often function as a vaporizer. The humidifier heats the water in its tank with an electrical heating element, producing hot steam that then exits the machine to humidify and slightly warm the air, Dr. Yong explains.

According to experts, both types of humidifiers are equally effective at adding moisture to the air in your home and reducing symptoms of colds and allergies. Luckily, there are options on the market that combine both cool and warm mist options, which might be the way to go if you have trouble deciding.

While personal preference will help you determine which is right for you (especially when you take into account various unique features like humidity readings, auto-shut-off, etc.) experts agree that it’s more important to consider how easy it is to clean, its size, and its ability to add humidity to your room or home.

Additionally, “Make sure you speak to your physician first to make sure it is a good idea for you, especially if you suffer from asthma and allergies,” Dr. Parikh explains.