Accidents happen, how to get blood out of mattress, don't worry. First, blot the area gently with a clean cloth to soak up excess blood. Then, mix cold water and salt to form a paste and apply it to the stain. Let it sit for 15 minutes, then gently scrub the area with a soft brush. Rinse with cold water and blot dry. If the stain persists, hydrogen peroxide can be used sparingly. Always check manufacturer guidelines and avoid hot water, as it can set the stain. Patience and care are key to successfully removing blood stains from your mattress.