Soak up spills as soon as they happen on the mattress pad using a thick towel or paper towels.
Mist the stain with hydrogen peroxide. Wait for five to eight minutes. Use a towel to blot the stain. If the stain persists, sprinkle borax on the mattress pad and rub it into the stain. Spray more hydrogen peroxide on the stain and blot again.
Spray the mattress pad with an upholstery cleaner. Allow several minutes for the cleaner to penetrate the stain. Blot the stained area with a towel. Upholstery cleaners work best for tough stains, such as urine and blood.
Put the mattress pad in the washing machine after treating the stain. Use warm water and 1 cup of laundry detergent. Set the machine on the normal cycle. Dry the pad on low or medium heat. If the pad has waterproof backing, let it air dry instead.