If You Smell This in Your Bathroom, You Have a Mold Problem, Experts Say

“One of my cleaning superpowers is being able to smell mold as soon as I walk into a client’s home,” says cleaning expert Sharon Garcia of @sharoncleanseverything on TikTok. It’s true: mold often has a signature scent that can be stronger to some people than others.

Experts say it’s important to keep “a nose out” for these odors as exposure to mold over time can pose serious health risks, including allergic reactions, respiratory issues, lung conditions, or, in the case of black mold, neurological problems and even organ damage.

If you get a whiff of the following smells in your bathroom, you may have a mold problem.

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Mold emits a distinctive smell because of the gaseous chemicals, called Microbial Volatile Organic Compounds (mVOCs), that are released as it grows and spreads, says Tony Abate, a certified mold inspector and vice president and chief technology officer at AtmosAir Solutions.

“Though you may not see it when you smell it, mold is lurking around somewhere, so you should investigate where it is coming from, paying close attention to areas where moisture is present.”

In most cases, these smells are described as:

Musty or Stale

Think of what wet laundry smells like when it’s been chilling in the washing machine for too long. This can also remind you of your grandma’s attic with its old, damp, and stagnant objects giving off an aged aroma.

Musty or stale is the most common smell associated with bathroom mold. “This kind of smell typically means mold is growing somewhere moisture has settled and stayed,” says Martyn Fowler, founder of Elite Renewables, with over 20 years of experience working on residential HVAC systems.

“The most common spots are behind tiles, in ceiling cavities, or around poorly sealed fixtures. It’s often the result of condensation that hasn’t had a way to escape.”

If the source is small, it can usually be removed by cleaning it with a stiff brush and a mix of warm water and mild detergent. Or, you can call a mold remediation specialist.

While small amounts of mold in your bathroom might not always be a big deal, its ability to trigger allergies and issues in people with weakened immune systems means it’s worth getting rid of as soon as possible.

Earthy

When you take an early morning hike and the scent of wet leaves and soggy dirt floods your nostrils, that’s described as “earthy.”

Experts say this type of smell is often a sign of black mold, known as Stachybotrys. This is the most dangerous type of mold, which produces mycotoxins—toxic substances that can cause a range of health issues when inhaled, touched, or ingested.

If you smell an earthy scent in your bathroom and are experiencing any brain fog, memory loss, fatigue, or mood swings, call a mold remediation specialist right away.

“Although mold begins growing fairly quickly (24 to 48 hours), it takes a while before you can detect the musty odor,” says Robert Weitz, an environmental testing expert and the founder, principal, and certified microbial investigator at RTK Environmental Group.

“Because mold is often hidden, growing on the back sides of walls and sheetrock, and under carpets and floorboards, the only way to be sure is to have a mold inspection performed by a certified professional.”

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Rotting or Fermenting

These smells are as gross as they sound. You know the scent of aging cheese or rotting wood? Yes, that’s a pretty positive sign that there’s a buildup of moisture hiding somewhere in your bathroom that’s seeping into porous materials like your drywall or baseboards.

In this case, you’ll want a professional to assess and remove the mold. “Qualified, trained mold inspection professionals offer the best protection, as they can provide you with a blueprint of where the mold is,” says Weitz. “To find out if the individual or company you want to hire is certified, search for them on the ACAC site.”

Ammonia or Chemicals

“If you can smell ammonia or sharp chemical-like scents, that could indicate longer-term water damage,” says Fowler.

“That kind of smell usually means moisture has been absorbed into materials like wood or plasterboard, which can lead to deeper mold colonisation. It’s something you’ll often find around toilet bases, under flooring, or where leaks have gone unnoticed.”

Call a pro who can fix the problem. They can also suggest how to improve your bathroom ventilation and keep all surfaces clean in order to prevent future growth.

“Good airflow is essential,” says Fowler. “Without it, steam lingers and creates the perfect conditions for mold to take hold behind the scenes.”