Myrrh gum is a great antiseptic and expectorant. It is also a great source of immune stimulating polysaccharides. One its effects rarely found in herbs is its ability to to block the enzyme hyaluronidase. As a hyaluronidase inhibitor it can block the spread of cancer cells, venoms and viruses in the system.
It is a resin though, and resins can be hard on the kidneys used long term. Therefore it is recommended that myrrh not be used internally for more than 2 months without a break.