Try hydrogen peroxide and pat it dry to loosen dried blood. A stain remover is called GONZO does an excellent job, available in larger grocery stores or bed bath & beyond. Good Luck.

This may sound strange, but if it is your own blood, Spit on it! The enzymes in your saliva will do wonders on the blood from your finger pricks.
Honest, it works. It was noted several times in a book I have that includes over 1000 "secrets" of quilters. I have done this after I have worked on a quilt and later found the dried blood stain. It works!

June in Cincinnati

I have used Fels Naptha to get out blood stains. If it's just a little spot, I just wet the fabric a little, rub an old tooth brush on the bar of Fels and then very gently brush using small circles. When I'm done I take a damp cloth to try to wipe away some of the soap, and then blot it dry with a cloth or paper towel. It's really been a lifesaver more than a few times.

Your own saliva has an enzyme that will remove your own blood out of fabrics. It won't work if the blood is someone else's. Everyone I know around here uses that trick and it has saved a lot of heart ache and not a few quilts. My kids are darn lucky I didn't know about that when they were young!! I can just picture it now - them sucking on the knees of their pants. :lol:
~Tiffany

Oh Tiffany, that was a funny "vision" and then when others followed I decided it was time to change the subject. It can get to be too much. Maybe we were blessed NOT to know those things.

LOL.

What is this 1000 book of secrets you speak of? It sounds like something every quilter should have in their quilt library. I have a great book of tips by other quilters, though it's a bit old and doesn't reflect a lot of the new things we've discovered/learned about quilting. That's okay with me, the book still has given me tons of tips that have improved my quilting. This 1000 book of secrets has me intrigued to see what all the tips are. I hate that there is stuff out there that I may not know. Hm, wonder what that says about my personality. :lol:
~Tiffany

Oxiclean is the absolute best for removing blood stains. Mix a paste with warm water and let it set for awhile. Then wash. May have to do it a few times, but usually comes out. Do not dry until blood is out. Good luck.