Yes, pee can ruin a mattress. It seeps into the foam layers. And if not cleaned properly, it candamage the fabric, foam, and other materials. Although getting rid of the traces of urine on yourmattress could be a real challenge, it is still possible. With the right cleaning method andmaterials (e.g., bicarbonate of soda, bleach, white vinegar), you can recover your mattress andmake it look as if that night of incontinence never happened.