Do Lavender and Tea Tree Oil Cause Hormonal Side Effects?

lavender and tea tree oil
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There's some concern that lavender oil and tea tree oil may cause certain hormonal side effects. Two types of essential oil commonly used in aromatherapy, these substances are found in a variety of personal care products. Some research has shown that lavender oil and tea tree oil may trigger such hormone-related side effects as breast growth in males.

When used as ingredients in skin-care and hair-care items, lavender oil and tea tree oil are thought to have cleansing effects.

Both oils are also said to aid in the treatment of skin conditions such as acne.

Related: Natural Remedies for Acne

Research on Lavender and Tea Tree Oil's Hormonal Effects

A study published in the New England Journal of Medicine in 2007 found that repeated topical use of products containing lavender oil and/or tea tree oil may increase risk of prepubertal gynecomastia (a rare condition marked by enlarged breast tissue in boys prior to puberty).

Before the study was conducted, three otherwise healthy boys (ages four, seven, and 10) were diagnosed with gynecomastia by a pediatric endocrinologist at the University of Colorado at Denver and Health Science Center's School of Medicine. All three boys had used either lavender-scented soap and skin lotions, or shampoos or styling products containing tea tree oil and lavender oil as ingredients. What's more, gynecomastia had either subsided or resolved in all three boys within several months of their discontinuing use of these products.

Given these circumstances, it was theorized that lavender oil and tea tree oil may act as endocrine disruptors (i.e., chemicals that interfere with the body’s system of glands and the hormones produced by them).

Suspecting that lavender oil and tea tree oil may have hormonal effects, a group of researchers at the National Institute of Environmental Health Sciences conducted a series of experiments on human cells.

These tests demonstrated that lavender oil and tea tree oils may mimic the action of estrogen (a female hormone known to promote the growth of breast tissue) as well as inhibit the activity of androgen (a hormone known to hinder breast-tissue growth). When combined, the researchers noted, lavender oil and tea tree oil have effects that make them "somewhat unique as endocrine disruptors."

Although further research is needed to confirm these findings, the study's authors stated that patients with gynecomastia should consider reducing their use of products containing lavender and/or tea tree oils. The authors also noted that use of such oils does not appear to have any long-term effects on hormonal levels.

Other Endocrine Disruptors in Personal Care Products

It's possible that other chemicals found in some personal care products containing lavender oil and tea tree oil may contribute to the products' potential side effects.

For example, synthetic chemicals such as phthalates and parabens (two substances sometimes used as ingredients in personal care products) have each been found to act as endocrine disruptors in scientific studies.

Therefore, it's possible that these chemicals may play a role in the hormonal side effects thought to result from the use of certain personal care products.

More Research on Lavender and Tea Tree Oil and Their Hormonal Effects

In recent years, studies evaluating the hormonal effects of lavender oil and tea tree oil have yielded mixed results.

In a preliminary study published in the International Journal of Toxicology in 2013, for instance, tests on rats indicated that lavender oil does not have estrogen-like activity.

On the other hand, a report published in the Journal of Pediatric Endocrinology & Metabolism in 2015 suggests that lavender may play a role in the development of prepubertal gynecomastia. This report included an analysis of the case reports involving the three boys who presented with prepubertal gynecomastia and were chronically exposed to lavender.


While the National Institutes of Health state that use of personal care products containing lavender oil and/or tea tree oil is possibly safe for most adults, such product use may be unsafe for young boys who have not yet reached puberty.

Go here to learn more about safe use lavender and tea tree oil (as well as other types of essential oils).


Diaz A, Luque L, Badar Z, Kornic S, Danon M. "Prepubertal gynecomastia and chronic lavender exposure: report of three cases." J Pediatr Endocrinol Metab. 2015 Sep 3.

Henley DV1, Lipson N, Korach KS, Bloch CA. "Prepubertal gynecomastia linked to lavender and tea tree oils." N Engl J Med. 2007 Feb 1;356(5):479-85.

Myers SL1, Yang CZ2, Bittner GD3, Witt KL4, Tice RR4, Baird DD5. "Estrogenic and anti-estrogenic activity of off-the-shelf hair and skin care products." J Expo Sci Environ Epidemiol. 2015 May;25(3):271-7.

National Institutes of Health. "Lavender: MedlinePlus Supplements." February 2015.

National Institutes of Health. "Tea tree oil: MedlinePlus Supplements." February 2015.

Politano VT1, McGinty D, Lewis EM, Hoberman AM, Christian MS, Diener RM, Api AM. "Uterotrophic assay of percutaneous lavender oil in immature female rats." Int J Toxicol. 2013 Mar-Apr;32(2):123-9.

Disclaimer: The information contained on this site is intended for educational purposes only and is not a substitute for advice, diagnosis or treatment by a licensed physician. It is not meant to cover all possible precautions, drug interactions, circumstances or adverse effects. You should seek prompt medical care for any health issues and consult your doctor before using alternative medicine or making a change to your regimen.

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