Last Updated On November 2nd, 2018

Not only is mold disgusting, but it can also be dangerous to you and your family. While we might be more accustomed to hearing about mold in the bathroom or kitchen, it can also occur in the bedroom, especially underneath your mattress. To prevent mold, you need to understand what it is, what causes it and how you can adjust your room to avoid it.

What Is Mold?

Mold is a type of fungi that are commonly found in homes and which thrives in moist environments. There’s also another type of fungi that you should be aware of, mildew, which is often confused with mold. In the case of your mattress, mildew is far more common, but most of us refer to it as a mold because we don’t understand the differences.

Mildew is a specific type of mold which has flat growth, and which remains on the surface of your mattress, allowing it to be easily removed. Mold on the other hand tends to creep deep into surfaces and pollutes them with mold. Fortunately, mildew can be quite easily removed whereas mold will require much more serious treatments.

Mildew is typically easy to identify because it appears as black dots, spread out and can be quite easily wiped off. Mold, on the other hand, has a fuzzier appearance like what you might see on old food and can be difficult to remove from the surface of your mattress. In almost all cases the “mold” that you’re dealing with is mildew.

Mold In Mattress Symptoms

Mold on edge of bedMold or mildew is microscopic, to begin with, meaning that you won’t be able to spot the early signs until it has grown to become visible to the naked eye. This problem is especially prevalent among those who don’t regularly turn and check their mattress when they are changing the sheets.

Typically, the earliest symptoms of mold under the mattress is a visible appearance of small black dots which you can notice far before you have any health problems or notice a stench. Keeping a close eye on your mattress is an essential tactic to guarding against the growth and occurrence of mildew.


The spores from the mold have a particularly persistent and strong smell which you might not associate with mold. Typically, when you think of it, you associate it with rotting food which tends to smell rancid, whereas spores on your mattress can have a damp or dank smell which you might notice over an extended period.

If you start to smell this, you should continue to search for the spores so that you can solve the issue. Depending on where they are and how dense the concentration of mold, you may notice the scent before you see any large density of mildew on the mattress.

Health Problems

Spore exposure can cause serious health problems, especially for those who are already sick or suffer from severe allergies. Mold under your mattress is particularly harmful because you spend long periods of time in bed and are therefore exposed to the danger for far longer than you might be in another part of your home.

Exposure to mold for this extended period will typically become evident through allergy-like symptoms such as headaches, itchy eyes, congestion, and exhaustion. If you’re feeling these symptoms, especially shortly after waking up, it could be the exposure to mold or mildew that is causing the symptoms.

Usually, you’ll start to feel better shortly after leaving the infected area, whether that is to leave the house to go to work or even to another part of the house without mold. This sudden change in feeling is a common symptom of mold that is on your mattress as opposed to throughout your home.


Moldy mattressOne of the earliest signs of mold is tiny black spots which will appear along the mattress, typically on the underside which either touches the ground, bed slats or box spring. This black mold is mildew, and if left it will progress and begin to cover the mattress, causing damage and releasing spores which can have a severe impact on your physical health.

Mold tends to appear as a fuzzy layer in large segments, often in white or black color. While mildew is evident because of its dotty and black appearance, which is unique to this type of fungus. Mildew is far more common under mattresses, and you can identify it by seeing how easy it is to wipe off with a wet cloth.

While mildew will slide off the surface of the mattress with very little pressure or effort, mold tends to be more stubborn and can require further treatment to remove. Check our mattress cleaning tips and more help and advice on this.

What Causes Mold?

For mold to grow, it needs a dark and wet environment where it can thrive without being disturbed. The underneath of your mattress provides this by guarding it against direct light and transferring the moisture from your bodies you sweat through the night. This combination of dark and sweat causes mold to grow quickly and abundantly.

Usually, your mattress won’t hold that moisture in large quantities or for long. Your bed sheets absorb much of it, and when you’re washing them regularly, it’s removed before any issues can develop. Similarly, the circulation of air underneath your bed should dry it out quickly and prevent mold from appearing.

However, when your mattress is close to the ground, directly touching it or lays on a solid box spring, air circulation is limited, and this adds in little extra heat and prevents it drying out. Both of these factors allow the mold to increase quickly, causing severe problems.

Mold Under The Bed

Mold under the bedMold typically occurs on the bottom of your bed, but it is possible for it to appear elsewhere first. The reason why the underneath of your bed is the most common spot for fungus growth is that it gets practically no light exposure and the air circulation is limited. While the top and sides of a bed see sunlight and artificial light, as well as receiving air every time, you lift your bed sheets.

To prevent this fungus from growing on the underneath of your bed, try to make a conscious effort to allow air flow under the mattress and bed. Open the window in your room as well as your bedroom door and a window in a different room, causing air flow throughout the home.

Similarly, ensure that there is a sizable gap between your mattress and the floor and preferably opt for bed slats rather than a box spring which completely prevents air from reaching the bottom of the mattress.

As always, it’s wise to lift up the mattress periodically to check for early signs of mold both visually and with your nose. When you do this, perhaps leave it leaning against the bed for a few hours, this will dry it out substantially, reducing the risk of fungus developing.

The Mattress-On-Floor Mold

The most likely circumstance for mold to develop on your mattress is when it is in direct contact with the floor. Regardless of whether your floor is carpeted or hardwood, the moisture is going to sit against the mattress, and no air can get to it to dry it out. Over time you have the perfect environment for fungus; warmth, dark and moisture.

It’s unsurprising then that unless you are careful about regularly washing your sheets, minimizing moisture and drying out the underside of the mattress, mold will inevitably develop. Ideally, you should purchase a raised bed from that uses slats to allow significant air flow, but if this is impossible, you should lean the mattress against a wall for at least a few hours each week to let it dry out.

Mold On Popular Mattresses

Innerspring Mattresses

Regardless of all the fascinating and incredible technology that is used in spring mattresses, the mold is still possible. As long as there is a warm environment underneath the mattress where light can’t reach, and moisture begins to settle, the fungus will eventually grow and spread.

To prevent this, it’s essential to raise the mattress up from the ground as much as possible to allow greater air circulation. To promote dryness, you can also use dehumidifying machines and open the windows occasionally to create a flow of air throughout the home which can help dry it out.

Memory Foam Mattresses

These mattresses are made using a variety of different foams. The problem with foam is that it absorbs moisture and holds it incredibly well, meaning that the sweat and liquid from your body can be held in the mattress for a long time. This moisture can get to the bottom of the bed where it can facilitate the growth of mold.

Memory foam mattresses are arguably more susceptible to mold than traditional coil or spring mattresses because memory foam lays flat against the ground and holds moisture well. These two factors ensure that there is less air flow against the bottom and there is plenty of moisture, both of which encourage the growth of fungus.