Remove blood stains from sheets by soaking them in cold water as soon as possible, using a detergent with enzymes, and using bleach suited for the material and color of the sheets. Hydrogen peroxide and ammonia also help remove stubborn blood stains. Don't dry the sheets in the dryer until the stain is gone.
As quickly as possible, soak blood-stained sheets in cold water. Flush them with cold water to remove the stain and prevent it from setting in any further. Even a spray with cool water aids in the stain removal process.
After the initial soaking or flushing, soak the sheets in clean, cold water with added detergent. To remove the blood, the detergent must have an enzyme in it to break down the protein components of the blood. The sheets must soak in the soapy water for at least half an hour. Check to see if the stain is gone, and soak again if necessary.
Wash the sheets in the warmest water recommended for their material once the soaking process lightens the stain. Add enzymatic detergent and appropriate bleach. Use chlorine bleach for white sheets and color-safe bleach for colored sheets. Check to see if the stain is gone, and repeat if necessary. Avoid drying the sheets to prevent any residue staining from setting permanently.
If the enzymatic detergent doesn't work, dab a mixture of hydrogen peroxide and ammonia on the stain. Allow it to soak in for a few minutes, and then rinse. Repeat as necessary, and then wash the sheets in warm water and detergent again. Once the stain is gone, dry the sheets normally.