Lavender oil has been linked to abnormal breast growth in young girls in a new study published in the Journal of Clinical Endocrinology & Metabolism, writes Jenny Berich.

Previous research has linked lavender-containing fragrances with breast growth in boys but this study, ‘Lavender Products Associated With Premature Thelarche and Prepubertal Gynecomastia: Case Reports and EDC Activities’, is the first to report abnormal breast growth in young girls.

The researchers studied four prepubertal patients (three girls and one boy) experiencing premature thelarche (breast tissue development in females before the age of eight without any other signs of puberty) or prepubertal gynecomastia (breast tissue development in males) who had a history of continuous exposure to lavender-containing fragrances.

The children, including a three-year-old girl who had been bathed in a lavender fragranced calming lotion since infancy and a seven-year-old girl who had inhaled the fumes of a lavender oil diffuser on her teacher’s desk for almost a year were evaluated in the Pediatric Endocrine Departments at the University of California-Irvine.

According to the researchers, the breast growth in all four children resolved three to six months after the lavender oil products were removed from their environment.

They also determined that “certain components of essential oils mimic estrogen and block testosterone, indicating that essential oils could be a source for the observed breast growth”.

Study lead investigator J. Tyler Ramsey, a postbaccalaureate research fellow at the National Institute of Environmental Health Sciences, said “the public should be aware of these findings and consider all evidence before deciding when to use essential oils”.

“It appears that essential oil products have the potential to cause premature breast growth in young girls and boys, so it may be best to discontinue using them on children.”

“It’s also important that physicians are aware that lavender and tea tree oils contain endocrine-disrupting chemicals and should be considered in the evaluation of premature breast development in young girls and boys, and the swelling of breast tissue in adult men.”

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