Even tea tree oil has been taken in up to 5-10 drops per cup of water and been tolerated well (by the people who choose to try it, like me.) The body likes essential oils, infectious gut buggers hate it, and there's the toxic link. (Dieoff is very hard on the body!)
After researching Turpentineparasite cleanse therapy, though, it's necessary to have a good mineral intake to protect the kidneys from damage on high Turpentine intake (proper turpentine, pine essential oil from gum resin).
Cinnamon essential oil is part of several candies and self-treatments. Products like doTerra's DDR Prime blend use cinnamon in their capsules for oral use, a heavy bomb against gut flora that's gone bonkers.