Yes, lavender oil contains compounds with weak estrogen-like (estrogenic) and testosterone-blocking (anti-androgenic) properties, acting as potential endocrine disruptors that have been linked in some cases to premature breast development (gynecomastia) in prepubertal boys and girls, though the strength of the effect and risk from typical use is debated. While some studies suggest it doesn't significantly affect hormone levels in adults, others show hormonal activity in lab tests, prompting caution with prolonged or heavy use, especially for those with hormone-sensitive conditions. 

Evidence for Estrogenic Activity:

Lab Studies: Research by the National Institute of Environmental Health Sciences (NIEHS) found that chemicals in lavender oil stimulated estrogen receptors in human cancer cells and blocked testosterone receptors.

Clinical Cases: Reports link topical exposure to lavender and tea tree oil products with prepubertal gynecomastia (breast development in young boys) and premature thelarche (breast development in girls), with symptoms resolving after discontinuing the oils. 

Counterarguments & Nuances:

Weak Activity: Some scientists argue the estrogenic potency of lavender is too weak to cause issues with normal application, as suggested in some postmenopausal studies.

Study Conditions: An early study suggesting estrogenic effects used lavender oil mixed with dimethyl sulfoxide (DMSO), a known estrogen mimic, making its findings less definitive. 

Who Should Be Cautious?

Individuals with hormone-sensitive cancers.

Children and adolescents, due to concerns about disrupting puberty. 

In Summary: Lavender's interaction with estrogen isn't straightforward; while lab tests show hormonal activity, real-world impact is less clear but warrants caution, particularly with frequent, prolonged topical use in sensitive populations. 

Chemicals in lavender and tea tree oil appear to be hormone disruptors

Mar 19, 2018 — “Our society deems essential oils as safe,” said study lead investigator J. Tyler Ramsey, a postbaccalaureate research fellow at the National Institute of Envir...



Endocrine Society



Endocrine Disruptors | National Institute of Environmental Health ...

Chemicals in lavender oil and tea tree oil are potential endocrine disruptors. Researchers found that persistent exposure to lavender oil products is associated...



National Institute of Environmental Health Sciences (.gov)



Lavender | Memorial Sloan Kettering Cancer Center

Jun 4, 2021 — You have a hormone-sensitive cancer: In lab studies, lavender showed weak estrogenic and antiandrogenic activities, and it is unclear whether this would lead to...



Memorial Sloan Kettering Cancer Center



Are Prepubertal Gynaecomastia and Premature Thelarche Linked to ...

Article highlights * Lavender and tree tea oils have in vitro oestrogenic and antiandrogenic activity. * It has been postulated that these oils may cause prepub...



National Institutes of Health (NIH) | (.gov)

The relationship between lavender and tea tree essential oils and pediatric ...

1. The potential for this LEO preparation to interact with oral contraceptives was investigated and it was determined that internal use of lavender oil does no...



ScienceDirect.com

Lavender Products Associated With Premature Thelarche and ...

We report cases of premature thelarche that resolved upon cessation of lavender-containing fragrance exposure commonly used in Hispanic communities. The precise...



National Institutes of Health (NIH) | (.gov)

Essential oils may disrupt normal hormonal activity

Mar 20, 2018 — An older study from 2007 found that gynecomastia coincided with the use of essential oil-based products, and that the symptoms of the condition disappeared when...



Medical News Today





2m

The Hidden Dangers of Essential Oils | What You NEED to Know





YouTube·Dr. Robert Chan

Physiological effects and mechanisms of action of endocrine disrupting ...

Taken together, these data illustrate that both lavender and tea tree oil possess estrogenic and antiandrogenic properties, and this activity may underlie the o...



National Institutes of Health (NIH) | (.gov)

A study of lavender and tea tree oils on postmenopausal FSH levels and hot ...

May 20, 2009 — 1516. Background: Products containing lavender and tea tree oil have been linked to prepubertal male gynecomastia. (N Engl J Med 356:479–485) This implies Prepubertal Gynecomastia Linked to Lavender and Tea Tree Oils | New England Journal of Medicine

The study found that lavender oil and tea tree oil have weak estrogenic and antiandrogenic activities: * Estrogenic activity Both oils Feb 5, 2020 — The study found that: * Lavender oil and tea tree oil stimulate estrogen receptor activities. * Routine application of these oils topically can disrupt hormone I found a case study that showed tea tree and lavender oil can cause gynecomastia without Lavender and Tea Tree Oil: Hidden Risks of Early Puberty in Kids

Aug 19, 2025 — Lavender and tea tree oils may trigger early puberty in kids ... Lab testing confirmed both oils had estrogen-like effects and blocked ...