Three-percent hydrogen peroxide can be used to remove tough spots and stains on clothing, including bloodstains. Pour on the spot, let sit for a minute, then rub and rinse with cold water. Note that peroxide is a bleach, so use carefully on colors—it might lift both the stain and color. To remove stains of unknown origin,
Readers Digest recommends this sure-fire method: Mix 1 teaspoon hydrogen peroxide with a little cream of tartar or non-gel toothpaste, rub the mixture into the stain with a soft cloth until the stain in lifted, and then launder as usual.