Strip all bedding and wash it
Vacuum the mattress thoroughly on all sides
Sprinkle baking soda evenly over the surface
Let the baking soda sit for several hours
Vacuum the baking soda completely
Spot-clean stains with mild soap and water
Blot moisture with a clean dry cloth
Use an enzyme cleaner for urine, sweat, or pet odors
Allow the mattress to air out in sunlight if possible
Use a fan to improve airflow and drying
Repeat baking soda treatment if odor remains
Place a mattress protector on after cleaning
Keep the room well ventilated to prevent odors from returning