Myrrh oil comes from a dried resin extracted from the Commiphora myrrha tree. Myrrh is traditionally used for respiratory congestion, coughs, and sore throat. It kills candidia yeast and other fungus, and promotes digestive health. Made into a mouthwash it kills the bacteria that causes gum disease and gingivitis and strengthens the immune system. A study conducted by Chinese researchers, published in the Journal of Medicinal Plants Research, also found that extracts made from myrrh resin may be effective against human gynecologic cancer cells.