How do I get mold out of my memory foam mattress topper?

@rory This “mildew” smell may well be a very toxic mold whose fumes are dangerous. With horrid infestations of mold many houses have been abandoned in an attempt to save their lives from toxic mold. A professional should be able to tell you how serious/if at all this problem is with your mattress topper. I wish you well! I do not think the mildew/mold can be removed.

I treated a foam mattress by spraying it very heavily with Lysol and leaving it out in the sun on a sheet. I did each side separately. It seemed to work.

My son said they laid their foam mattress on a sheet and hosed it down, then left it in the very hot sun for one day on each side.

I would throw it in the trash.

If you want to give it a try I would soak it in water with some bleach, rinse well, and dry thoroughly. Does it fit in a washer and dryer? Be careful not to shrink it though.

You don’t.

I just thought of something else. If it fits in the washer you can try adding vinegar to a wash. If your washing machine has a sanitizing setting you can try that, but it might shrink.

If a couple days in the sun don’t take care of it get a new one. It’s just a topper anyway.