Rinsing and blotting with cold water while the blood is still fresh is an effective way to remove the stain from carpet or clothing. Dishwashing detergent mixed with cold water or ammonia mixed with warm water helps remove remaining blood.
Hot water makes the blood stain set into the fabric, so using cold water is necessary to effectively remove the blood. When removing the stain from carpet or upholstery, use a blotting action instead of rubbing. Blotting with a wet cloth helps soak up the blood. Rubbing with a cloth grinds the blood into the fabric or carpet. If the blood is already dry, a brush can help loosen some of the chunks before you wash it out.
If water alone doesn't remove the blood from carpet or upholstery, mix a few drops of dishwashing detergent with cold water. Repeat the blotting method with a clean cloth dipped in the soapy water. One tablespoon of ammonia mixed with 1/2 cup of warm water is another option. Test the solution on a hidden spot first to check for potential damage.
When washing blood from clothing, rinse the item under cold water from the tap. Add a few drops of soap to the fabric. Work the soap into the stain before rinsing with more cold water.
When you remove most of the stain, put the item through a cold cycle in the washing machine. Use a laundry stain remover if necessary. Do not dry the item until the stain is gone.