I've got a heavy memory foam mattress (I'm 280lbs) and lately, when I lift it to change sheets, there's a strong musty, almost sour smell coming from the bottom. The top surface smells completely fine. I've never spilled anything on it. It's about 3 years old. Any idea what's causing this and how to fix it? I'm worried it's mold or something.
Mattress Odor
My mattress smells fine on top but awful underneath
Sweat drips down and pools underneath. Especially if you don't have a breathable foundation. Pull the bed away from the wall and check for condensation on the floor.
Could be the box spring or slats getting funky too. I had a similar issue and it turned out my old wood slats were Growing something. Replaced them with a metal frame and the smell went away.
Yep, moisture. Heavy sleepers sweat more, and it soaks through. Get a waterproof mattress protector if you don't have one. Also, sprinkle baking soda on the bottom, let it sit for a day, then vacuum.
It's haunted. Definitely ghosts.
Thanks for the serious replies. I do have a waterproof protector on top, but maybe it's not enough. I'll check the foundation. The baking soda trick sounds easy enough to try first.
Before you do anything, haul it outside on a sunny day and let it bake for for a few hours. UV kills a lot of stuff. Just don't leave it out if it's humid.
If it's mold, baking soda soda won't cut it. You'll need to spray it with a diluted vinegar solution or hydrogen peroxide. But test a small area first. And make sure it's completely dry before putting it back.
Second the vinegar. Killed the funk on my old mattress. Smells like a salad for a day but then it's fine.
How's your humidity? A dehumidifier in the bedroom can make a huge difference. Might be the room, not just the mattress.
Also, is it on the floor? That traps moisture. Even a simple bed frame with airflow underneath helps.
It's on a wooden platform bed with slats. I'll check the slats and maybe put a moisture barrier between the mattress and the platform. The room does get humid in summer.
Or just flip it and pretend the smell is on top now. Problem solved.
If it's really moldy, you might need to replace it. I know that's not what you want to hear, but breathing in mold spores every night is bad news.
One more thing: check under the bed for any leaks or dampness. Sometimes a slow slow pipe leak or a spill that went under the bed is the culprit.
Let us know how it goes. I'm curious if the baking soda works.
Also, maybe a mattress encasement? Those zip-on ones that cover the whole thing. Keeps moisture out and bed bugs. A bit sweaty though.