Are blood stains on cotton permanent?

Blood stains are removable. I treat blood stains instantly and they always come out. Just use cold water and laundry detergent on the stain itself to spot wash and it will come out.

If the blood stain is set in, then you may need to soak it in cold water over night. If the stain still remains, put some peroxide in the cap of the bottle and use a q-tip to spot the peroxide on the stain. You will see the stain bubble up in white foam, this is a good thing. Rinse and repeat until the stain is removed. DO NOT leave the peroxide on the fabric for a long time and do not allow to dry. Rinse, repeat. Peroxide can remove some of the dye in the fabric, so test a seam first.

If nothing gets rid of a stain and it is on white fabric, I use bleach as a very last resort. Bleach, used with a q-tip on a stain will remove it. Again, rinse and do not allow the bleach to stay on the fabric long because it has the capability to weaken the fabric fibers and ruin the garment/sheet/blanket, or what have you.

As Jimmy C stated, removing the body is the hardest part!

Not if laundered correctly. Always soak ASAP, use stain stick or spray, wash in cold water( always!). Never dry until stain is gone.

Blood stains wash off. The hard part is getting rid of the body.

Soak for an hour in cold salt water. Rinse well then wash as usual.

It depends. If washed in cold water with a biological detergent then they are easily removed. If they get hot though they get much harder to remove.