We get questions sometimes about the use of ingredients such as lavender and tea tree oil in topical products. Although these may be generally safe and helpful, many "natural" products can cause side effects. I just read a report today by Dr. Stan Block, MD in Pediatric Annals about an issue with lavender and tea tree oils used in various "calming creams" applied to the chest for young children. He reported a number of cases of breast swelling (premature gynecomastia) in these children after the cream had been repeatedly massaged into the chest. The vast majority of the cases of breast swelling stopped after the creams were stopped. It is not known for sure how these products caused the swelling.
This information is not meant to stop you from using these products all together, but if something unusual such as breast swelling is occurring at a young age, it is good to examine the possible causes. And it is possible that a product that is generally safe and tolerated by others may be causing more harm than good.