Lavender and Tea Tree Oil May Cause Breast Development in Young Boys


Lavender and Tea Tree Oils May Mimic Estrogen Effects in Boys

A study published in  the New England Journal of Medicine suggested that the use of topical agents containing lavender oil and/or tea tree oil may cause breast tissue (called gynecomastia) to develop in young boys. This finding was reported by Clifford Bloch, M.D., a pediatric endocrinologist at the University of Colorado at Denver and Health Science Center’s School of Medicine. 

This doctor found that three of his young male patients with unexplained breast development (gynecomastia) had all used lotions, creams, shampoos, styling products or soap with lavender or tea tree oil in them.  Once these products were stopped, the gynecomastia also resolved.

Researchers who conducted laboratory studies at t he National Institute of Environmental Health Sciences (NIEHS), part of the National Institutes of Health (NIH), confirmed that there may be an association between the use of products containing these oils and prepubertal breast development in boys, but cautioned more research is needed.  Large scale epidemiologic studies are needed to determine the association of lavender and tea tree oils and gynecomastia.

Ken Korach, Ph.D., chief, Laboratory Reproductive and Developmental Toxicology at NIEHS confirmed that his laboratory studies confirmed that pure lavender and tea tree oils can indeed mimic the effects of the female hormone estrogen and inhibit the effects of androgens (male hormones).

Interestingly enough, the male and female hormone levels in the three boys with gynecomastia were not changed by their exposure to lavender or tea tree oil. Therefore, Derek Henley, Ph.D., the lead NIEHS author on the study hypothesized that lavender and tea tree oils may be  “endocrine disruptors.”    Endocrine disruptors are agents that interfere with the activity of hormones but not affect the levels of the hormones themselves.  They may alter signaling of the hormones, resulting in abnormal endocrine effects.

Studies are need to decide whether lavender and tea tree oils have the same effects in females or adults.

The National Institute of Environmental Health Sciences (NIEHS),  a part of the National Institutes of Health, supports research to understand the effects of the environment on human health. 

Reference:

Henley DV, Lipson N, Korach KS, Bloch CA 2007 Prebubertal gynecomastia linked to lavender and tea tree oils. New England Journal of Medicine 365(5): 479-485  

 Photograph of Australian Tea Tree courtesy of J. Brew.

Last updated April 18, 2010 by Dr. Vee

           

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