Of all the stains that might get on your carpet, blood stains can be among the most stubborn. Whether you accidentally cut your finger or a toddler ran down the hallway with skinned knees, you can get the stains out quickly and easily with a few different methods. Getting blood out of carpet is typically considered difficult because the hemoglobin in blood actually binds it to the carpet fibers. So, you'll need a cleaning solution that will loosen the binding between the hemoglobin and individual carpet fibers in addition to removing the stain.
With water only
If the blood stain is fresh, then you might be in luck. Water alone will lift fresh blood stains as long as the stain has not had time to set. Grab a washcloth and dampen it with cool water, then press it gently on the stain. The pressure should help to soak up the stain into the washcloth. Do not rub the cloth, since this can spread the stain further. Also, remember that cold water works best because it prevents the stain from setting and expanding further.
Mix dishwashing or laundry detergent with cold water and use a cloth to press the soapy mixture on top of the blood stain. Your dishwashing liquid is a great stain fighter and it can help loosen the bonds in blood stains to clean your carpet. You may have to rewet the cloth multiple times to completely remove the stain, but if the blood is still wet then the stain should disappear without using harsher chemicals.
If gentler methods don't work, turn to a stronger cleaning solution. Ammonia is a great solution for removing blood stains. Remember, use ammonia by itself and never combine it with bleach, as the combination can create toxic fumes. Apply ammonia directly on the blood stain and blot until it's fully lifted. Dab the remaining ammonia away with a cold, wet cloth and vacuum the area when you're finished to restore carpet fibers.