I used to work at a dry cleaners and they used ammonia. It will not hurt your fabric.

If it is your blood use your saliva to loosen it, then use a cold water dipped cloth to keep removing it, also put another dry cloth behind so the stain will migrate into the dry cloth, which you will need to keep moving to a dry area as you push from the top with the top wet one. If it has set too long you may need to use the peroxide after the wet/dry method.