Why You Shouldn’t Ignore Cleaning Your Humidifier

A humidifier can be a lifesaver when indoor air gets dry, helping to soothe irritated sinuses, prevent nosebleeds, and relieve dry skin. But if you’re not cleaning it regularly, it could be spreading bacteria, mold, and other harmful particles into the air you breathe.

We spoke with Jonathan D. Sexton, PhD, a research scientist at the University of Arizona, to learn about the hidden dangers of a dirty humidifier and how to keep yours safe to use.

What Germs Can Grow in a Humidifier?

Humidifiers create the perfect environment for bacteria, mold, and other pathogens to thrive. According to the Children’s Hospital Colorado, some of the most common contaminants include:

• Mold spores

• Bacteria like Pseudomonas aeruginosa and Legionella

• Dust mites, which flourish in high humidity

The location of your humidifier may also influence the type of bacteria that accumulate. Sexton notes that placing one in a kitchen could encourage foodborne bacteria, while a unit near a bathroom may harbor more fecal organisms.

Can a Dirty Humidifier Make You Sick?

Unfortunately, yes. Breathing in contaminated mist from an unclean humidifier can trigger respiratory problems, infections, and allergic reactions.

1. It Can Lead to a Lung Infection

Cool mist humidifiers, especially ultrasonic models, can disperse bacteria and mold directly into the air. When inhaled, harmful microbes like Legionella can cause Legionnaires’ disease, a severe lung infection that may require hospitalization, according to the Centers for Disease Control and Prevention (CDC).

Similarly, Pseudomonas aeruginosa, another bacteria commonly found in humidifiers, can lead to pneumonia and other serious infections.

2. It Can Worsen Asthma and Allergies

If you have asthma, a dirty humidifier can trigger attacks by increasing airborne allergens like mold and dust mites. The American Lung Association (ALA) warns that dust mites thrive in humid environments, worsening symptoms like sneezing, congestion, and difficulty breathing.

Additionally, minerals from tap water can accumulate in the device and be released into the air as a fine white dust. Inhaling this dust may further irritate sensitive airways.

3. It Can Cause Flu-Like Symptoms

Even in people without underlying health conditions, exposure to bacteria and mold from a contaminated humidifier can lead to flu-like symptoms such as:

• Persistent cough

• Shortness of breath

• Fever and muscle aches

How Often Should You Clean Your Humidifier?

Experts recommend cleaning your humidifier more frequently than you might think:

• Every 3 days: The Mayo Clinic advises scrubbing your humidifier every few days to prevent bacteria buildup.

• At least once a week: If cleaning every three days isn’t realistic, once a week is the minimum recommended by the Children’s Hospital Colorado.

How to Clean Your Humidifier Properly

While cleaning methods vary by model, here are general steps recommended by the Children’s Hospital Colorado:

1. Unplug and Empty the Tank

Always start by turning off and unplugging your device before cleaning.

2. Use White Vinegar

Fill the tank with enough distilled white vinegar to cover all areas that come into contact with water. Let it sit for 20 minutes to dissolve mineral deposits and kill bacteria.

3. Scrub the Interior

Use a toothbrush or small brush to scrub any crevices where mold or slime may accumulate.

4. Rinse and Air Dry

Thoroughly rinse the tank with clean water and let it air dry completely before refilling.

Additional Maintenance Tips:

• Use distilled or demineralized water to reduce mineral buildup.

• Change the water daily to prevent bacteria from multiplying.

• Replace filters regularly if your model includes them.

• Store properly by draining and drying the humidifier completely before putting it away.

Are Humidifiers Worth the Risk?

Yes as long as you clean them regularly. Sexton compares humidifier maintenance to car upkeep: "If you never change your car’s oil, it will break down. Likewise, if you neglect cleaning your humidifier, someone might get sick."

If maintaining a humidifier feels like too much effort, consider alternative moisture-boosting solutions, such as saline nasal sprays, which add moisture without the risk of bacteria or mold exposure.

The Bottom Line

Failing to clean your humidifier can expose you to mold, bacteria, and allergens that may lead to infections or respiratory problems. To safely enjoy the benefits of humidifiers, regular cleaning is essential. If you’re unable to maintain it properly, it may be best to store it until you can.

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