Memory Foam Molds

Unfortunately, mold on your memory foam mattress is a sign that it's time to throw it away. Although you can remove surface mold with a vacuum cleaner, household cleaners and a bit of time in the sun, there is no way to remove mold from deeper parts of the mattress. Instead, you'll need to get a new mattress and take steps to prevent mold from growing again.
The Problem

Mold likes damp dark places, and there are few places darker than the core of a memory foam mattress. Memory foam mattresses consist of a memory foam casing and a polyurethane foam inner core. This inner foam core contains millions of air pockets, all of which are capable of housing mold spores. Moisture enters the mattress as you sweat at night or when humidity levels in your home are high. Once moisture and mold spores find their way into the depths of a foam mattress, there is simply no way to get them back out. It thrives inside the millions of air pockets within the foam core. Even if you clean the mold from the surface of the mattress, you risk breathing in dangerous mold spores from within it with every use.
Why It's Dangerous

Exposure to mold and inhalation of mold spores can cause health problems. Anyone can experience nasal congestion,
throat irritation, wheezing, coughing, itchy skin and irritated eyes after mold exposures. Those with mold allergies will experience the same symptoms but to a greater degree. People who are already fighting lung disease or immune system disorders can develop serious long-term lung diseases when exposed to mold. Even in healthy people without allergies, prolonged and repeated mold exposure may result in asthma, respiratory illness or pneumonitis (lung tissue inflammation). Sleeping on a moldy mattress could make you quite ill and is simply not worth the risk.
Mold Prevention

It may be too late to save your current mattress, but you can take steps to prevent mold on the next one.
Place your new memory foam mattress in a mattress cover that is waterproof but breathable. Breathable and waterproof may not seem like they go together, but you can buy mattress covers made of special materials that are both. Your local mattress store is a good place to find them. Further protect your mattress by making sure it is on a breathable base. Plywood, captain's beds and platform beds don't allow air circulation and contribute to mattress mold. Use a slatted bed system or breathable box spring system under your mattress. Run a dehumidifier in your bedroom if it tends to be humid and keep wet towels, clothes swimsuits and hair off of your
bed.