Saturate a dye-free rag with cold water. Blot the water-soaked cloth onto the blood-stained shirt to rinse out excess blood. Prevent spreading the blood further by rinsing the cloth with fresh water between blots.
Prepare a stain-removal solution of 1 tsp. of dish soap, 1 tsp. of ammonia and 1 cup of cold water. Mix the soap, ammonia and water in a clean bowl.
Dampen another dye-free rag in the stain-removal solution. Use the saturated cloth to blot the shirt and dissolve the remaining blood. Rinse the cloth with fresh water between blots.
Moisten a third dye-free rag with cold water. Blot the water-soaked cloth onto the shirt to rinse out the soap solution.
Examine the shirt for blood. If traces of the red blemish persist, resume blotting the shirt with the stain-removal solution until the blood dissolves completely.
Launder the dress shirt in your clothes washer with warm water and 1/4 cup of chlorine bleach.
Lay the shirt flat to air-dry.