"How to get blood out of a mattress" To remove blood stains from a mattress, start by blotting the stain with a cloth or paper towel to absorb excess blood. Mix cold water with a mild detergent and gently sponge the stain, avoiding excessive saturation. For tougher stains, you can try using hydrogen peroxide or a paste made of baking soda and water. After treating the stain, blot the area with a clean cloth to remove any excess moisture. Allow the mattress to dry thoroughly before making the bed.