Tea tree oil would be CONTRAINDICATED on a BF mom's nipples. Although it has its uses as a treatment for skin conditions, it should not be used internally. The risk of the infant ingesting tea tree oil from mom's nipples would contraindicate its use. When taken internally, even small amounts of tea tree oil can produce neurologic toxicity including confusion, muscle weakness, and tremors. Tea tree oil can also cause contact dermatitis if applied to broken skin. Source: Kemper, Kathi J., MD, MPH "Seven Herbs Every Pediatrician Should Know" in Contemporary Pediatrics, Vol. 13, No 12, December 1996, pg. 79 ff. Hope this helps. Linda Shaw MD