If possible, treat the stain while it's wet, and then use these easy steps from Michael Dimopoulos, a and the founder of Lazy Susans Cleaning, to remove blood stains on clothing, carpet, mattresses, or furniture.
1. Rinse the fabric under cold water, or blot the stain with a clean wet cloth. Don't use hot water—this will cause the stain to set.
2. Continue to rinse or blot until the stain comes out. You can also apply some dish soap to the stain if need be, and then launder.
If this doesn't work, you can try to use a small amount of hydrogen peroxide on the fabric, but do this with caution—this solution may weaken or stain certain fabrics. And for larger items that you can't put in the washing machine like mattresses and furniture, apply a salt and water paste with a toothbrush.