To remove a blood stain, mix 1/4 teaspoon of liquid dishwashing detergent with 1 cup warm water, and blot the cleaner onto the carpet using a white cloth. Continue blotting until the stain is transferred to the cloth then rinse the carpet by blotting it with cold water. Dry the carpet with paper towels.
Alternately, mix 2 tablespoons of white, non-sudsing ammonia with 4 cups of cold water, and blot the cleaning solution onto the stain beginning at the outside edge of the stain. Working inward toward the center of the stain, continue to apply the cleaning solution by dipping the cloth into the cleaner to apply it.
Allow the cleaning solution to remain on the carpet for five minutes, and blot the stain with a clean cloth to transfer the stain to the cloth. Rinse the area with a small amount of cold water, and place a thick layer of paper towels over the stain. Weigh the paper towels down with a heavy glass object to absorb the moisture, and vacuum the carpet after it is dry.
Another option is to blot the stain with rubbing alcohol and a clean cloth until the stain is lifted. Rinse the carpet with cool water after cleaning it, and place weighed-down paper towels on the stain to dry the carpet.