Dismiss Modal

Causes

Mold

Choose a preferred language


What is mold?

Mold is a member of the fungus family. It's rarely killed by heat or cold exposure. Mold stays inactive (dormant) until a certain season, such as spring or fall, or when favorable environmental conditions appear. Then it grows and thrives.


Where does mold grow?

Mold lives in moist conditions where there is oxygen and material to feed on. Mold may be found both outdoors and indoors.

Outside, mold is most often found:

  • On dead or dying vegetation, such as rotting leaves and logs.

  • In moist, shady areas.

Inside, you may find mold in:

  • Damp basements and closets.

  • Bathrooms.

  • Food storage areas.

  • Refrigerators.

  • House plants.

  • Air conditioners and humidifiers.

  • Mattresses or upholstered furniture that is damp.

  • Garbage containers.


What is mold allergy?

Mold spores or fragments may be breathed in through the nose and into the lungs. In some people, they may cause allergic reactions or asthma.

There is no known relationship between an allergy to the mold Penicillium and an allergy to the antibiotic penicillin, which is made from the mold. Talk with your child's health care provider for more information.

© 2000-2026 The StayWell Company, LLC. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions.

Find the right providers for your needs.

CalOptima Health works with thousands of Orange County providers, including doctors, specialists, health networks, medical groups and more.

Find a Doctor

Get Care Now

Your health is everything to us. Please reach out for support if you need it.

Get Care Now
Related Articles
Read article
Allergies
Food Allergy

The best way to deal with food allergies is to stay away from the foods you are allergic to. Understand and be aware of the foods that you have reacted to. Also be cautious of foods or dishes that may have flavorings or small amounts of foods that you are allergic to. Read on to learn more.

Read article
Wellness
Milk Allergy Diet

Detailed information on milk allergy, a type of food allergy. Learn about how to read a label for a milk-free diet, other possible sources of milk, and tips for eating out.

Read article
Allergies
Controlling Allergens: Dust Mites in the Bedroom

Dust mites are tiny bugs that live in warm, damp places. They're too small to see. And they're found in nearly every home. Read on for helpful tips on controlling dust mites in your bedroom.

Read article
Allergies
Allergens: Pollen

Pollen is the most common cause of hay fever. Read on for more information--and helpful tips for reducing the effects of hay fever during pollen season.