Humidifiers: Why you might need them (2023)

Humidifiers: Ease skin, breathing symptoms

Humidifiers can ease problems caused by dry air. But they need regular maintenance. Here are tips to ensure your humidifier doesn't become a health hazard.

By Mayo Clinic Staff

Dry sinuses, bloody noses and cracked lips — humidifiers can help soothe these familiar problems caused by dry indoor air. And cool-mist humidifiers also may help ease symptoms of a cold or other respiratory condition.

But be cautious: Although useful, humidifiers can make you sick if they aren't maintained properly or if humidity levels stay too high. If you use a humidifier, be sure to check the humidity levels and keep your humidifier clean. Dirty humidifiers can breed mold or bacteria. If you have allergies or asthma, talk to your doctor before using a humidifier.

What are humidifiers?

Humidifiers are devices that release water vapor or steam to increase moisture levels in the air (humidity). Types of humidifiers include:

  • Central humidifiers. These are built into home heating and air conditioning systems. They are designed to humidify the whole house.
  • Ultrasonic humidifiers. These produce a cool mist with ultrasonic vibration.
  • Impeller humidifiers. These humidifiers produce a cool mist with a rotating disk.
  • Evaporators. Evaporators use a fan to blow air through a wet wick, filter or belt.
  • Steam vaporizers. Steam vaporizers use electricity to create steam that cools before leaving the machine. Avoid this type of humidifier if you have children. The hot water inside this type of humidifier may cause burns if spilled.

Ideal humidity levels

Humidity is the amount of moisture in the air. Humidity varies depending on the season, the weather and your home's location. Generally, humidity levels are higher in the summer and lower in the winter. Ideally, humidity in your home should be between 30% and 50%. Humidity that's too low or too high can cause problems.

  • Low humidity can cause dry skin, irritate your nasal passages and throat, and make your eyes itchy.
  • High humidity can make your home feel stuffy and can cause condensation on walls, floors and other surfaces. Condensation can trigger the growth of harmful bacteria, dust mites and molds. These allergens can cause respiratory problems and trigger allergy and asthma flare-ups.

How to measure humidity

The best way to test humidity levels in your house is with a hygrometer. This device looks like a thermometer. It measures the amount of moisture in the air. Hygrometers can be purchased at hardware stores and department stores. When buying a humidifier, consider purchasing one with a built-in hygrometer that keeps humidity within a healthy range (humidistat).

Humidifiers, asthma and allergies

If you or your child has asthma or allergies, talk to your doctor before using a humidifier. Increased humidity may ease breathing in children and adults who have asthma or allergies, especially during a respiratory infection such as a cold. But mist from a dirty humidifier or increased growth of allergens caused by high humidity can trigger or worsen asthma and allergy symptoms.

When the air's too damp: Dehumidifiers and air conditioners

Just as air that's dry can be a problem, so can air that's too moist. When humidity gets too high — common during summer months — it's a good idea to take steps to reduce indoor moisture. You can reduce humidity by:

  • Using an air conditioner. Central or window-mounted air conditioning units dry the air, keeping indoor humidity at a comfortable and healthy level.
  • Using a dehumidifier. These devices collect excess moisture from the air, lowering humidity levels. Dehumidifiers work like air conditioners, without the "cooling" effect. They're often used to help dry out damp basements.

Keep it clean: Dirty humidifiers and health problems

Dirty reservoirs and filters in humidifiers can quickly breed bacteria and mold. Dirty humidifiers can especially cause problems for people with asthma and allergies. But even in healthy people, dirty humidifiers have the potential to trigger flu-like symptoms or even lung infections when the contaminated mist or steam is released into the air. Evaporators and steam vaporizers may be less likely to release airborne allergens than may cool-mist humidifiers.

Tips for keeping your humidifier clean

To keep humidifiers free of harmful mold and bacteria, follow the guidelines recommended by the manufacturer. These tips for portable humidifiers also can help:

  • Use distilled or demineralized water. Tap water contains minerals that can create deposits inside your humidifier that promote bacterial growth. When released into the air, these minerals often appear as white dust on your furniture. It's also possible for you to breathe in some minerals that are spread into the air. Distilled or demineralized water has a much lower mineral content than does tap water. Also, use demineralization cartridges or filters if recommended by the manufacturer.
  • Change humidifier water often. Don't allow film or deposits to develop inside your humidifiers. Empty the tanks, dry the inside surfaces and refill with clean water every day if possible, especially if using cool-mist or ultrasonic humidifiers. Unplug the unit first.
  • Clean humidifiers every 3 days. Unplug the humidifier before you clean it. Remove any mineral deposits or film from the tank or other parts of the humidifier with a 3% hydrogen peroxide solution, which is available at pharmacies. Some manufacturers recommend using chlorine bleach or other disinfectants.
  • Always rinse the tank after cleaning. This can keep harmful chemicals from becoming airborne — and then inhaled.
  • Change humidifier filters regularly. If the humidifier has a filter, change it at least as often as the manufacturer recommends — and more often if it's dirty. Also, regularly change the filter in your central air conditioning and heating system.
  • Keep the area around humidifiers dry. If the area around a humidifier becomes damp or wet — including windows, carpeting, drapes or tablecloths — turn the humidifier down or reduce how often you use it.
  • Prepare humidifiers for storage. Drain and clean humidifiers before storing them. And then clean them again when you take them out of storage for use. Throw away all used cartridges, cassettes or filters.
  • Follow instructions for central humidifiers. If you have a humidifier built into your central heating and cooling system, read the instruction manual or ask your heating and cooling specialist about proper maintenance.
  • Consider replacing old humidifiers. Over time, humidifiers can build up deposits that are difficult or impossible to remove and encourage the growth of bacteria.

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June 08, 2021

  1. Use and care of home humidifiers. U.S. Environmental Protection Agency. Accessed Feb. 9, 2021.
  2. Dirty humidifiers may cause health problems. U.S. Consumer Product Safety Commission. Accessed Feb. 9, 2021.
  3. The inside story: A guide to indoor air quality. U.S. Consumer Product Safety Commission. Accessed Feb. 9, 2021.
  4. Indoor air pollution: Introduction for health care professionals. U.S. Consumer Product Safety Commission. Accessed Feb. 9, 2021.
  5. Pappas DE. The common cold in children: Management and prevention. Accessed Feb. 9, 2021.

See more In-depth

See also

  1. Antibiotics: Are you misusing them?
  2. Avoid rebound nasal congestion
  3. Breastfeeding and medications
  4. Can chicken soup cure a cold?
  5. Chicken soup: Can it treat a cold?
  6. Cold and flu viruses: How long can they live outside the body?
  7. Cold or allergy: Which is it?
  8. Cold remedies
  9. Cold symptoms: Does drinking milk increase phlegm?
  10. Common cold
  11. COVID-19: How can I protect myself?
  12. Cough
  13. Vitamin C and mood
  14. Does zinc work for colds?
  15. Exercise and illness
  16. Fatigue
  17. Hand-washing tips
  18. Have a cold? Common sense rules
  19. Have a cold? Fight back with humidity
  20. Have a cold? Fight it with fluids
  21. Headache
  22. Honey: An effective cough remedy?
  23. How well do you wash your hands?
  24. Humidifier care 101
  25. Is antibacterial soap a do or a don't?
  26. Nasal Cleaning
  27. Nasal congestion
  28. Neti pot: Can it clear your nose?
  29. Plugged ears: What is the remedy?
  30. Runny nose
  31. Stuffy nose? Try saline spray
  32. Symptom Checker
  33. Vicks VapoRub: An effective nasal decongestant?
  34. Vitamin C: Can it prevent colds?
  35. Warm-mist versus cool-mist humidifier: Which is better for a cold?
  36. Watery eyes
  37. What is MERS-CoV?
  38. When to Take Your Child to the E.D.
  39. Do zinc supplements shorten colds?


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