Three cases of gynecomastia (enlarged breasts) in prepubertal boys who were otherwise healthy were found to be caused by the topical application of products containing lavender and tea tree oils. The boys were aged 4 years 5 months, 10 years 1 month, and 7 years 10 months. Each boy had normal serum concentrations of endogenous steroids. The products linked to the enlarged breasts were a healing balm containing lavender oil, a hair styling gel and a shampoo both listing Lavandula angustifolia (lavender) oil and Melaleuca alternifolia (tea tree) oil as ingredients, lavender-scented soap and lavender-scented commercial skin lotions. After discontinuing the use of these products, the gynecomastia resolved within several months in each of the patients. Testing using dose-response experiments in human breast cancer cell lines led the authors to conclude that the two oils have estrogenic and antiandrogenic properties.

The current study was designed to compare 4-week courses of aromatherapy massage and massage alone in 42 patients with advanced cancer. The patients were randomly assigned to receive weekly massages with inert oil mixed with lavender essential oil (aromatherapy group), inert oil only (massage group), or no intervention. The study used a Visual Analogue Scale of pain intensity, the Verran and Snyder-Halpern sleep scale, the Hospital Anxiety and Depression scale, and the Rotterdam Symptom Checklist as outcome measures. There were no demonstrable significant long-term benefits of aromatherapy or massage in improving pain control, anxiety or quality of life. However, sleep scores improved significantly in both the massage group and the aromatherapy group. There also were reductions in depression scores in the massage group. The authors conclude that the addition of lavender essential oil did not appear to increase the beneficial effects of massage. Patients with high levels of psychological distress responded best to these therapies.

To study the effects of the monoterpene perillyl alcohol in the first stages of hepatocarcinogenesis, male Wistar rats were initially treated with a single dose of the carcinogen N-nitrosomorpholine and subsequently were treated with the potent tumor promoter PB until the end of the experiment. Subgroups of rats received either perillyl alcohol or phenobarbital in the diet. Rats were killed at multiple time points. A key finding was that 87 days of perillyl alcohol diet revealed no protective effect, rather, similar to PB treatment, it increased the growth of G+ cell foci. The authors concluded that perillyl alcohol exerted no detectable chemopreventive effect in the early stages of rat liver cancer. Instead, it exerted a PB-like tumor promoting activity.

The current study investigated the effects of citral in a rat model for benign prostatic hyperplasia. A four-month course of citral treatment of male Copenhagen rats via the transdermal route resulted in marked hyperplasia of glandular epithelium and interglandular stroma in the ventral prostate. Further investigation showed that application of citral directly to the vagina in female rats with their ovaries removed resulted in increased proliferation of vaginal epithelium and a significant increase in 5-bromodeoxyuridine incorporation in vaginal epithelial cells, in other words a similar effect to that of the application of estrogen. Citral proved to inhibit estrogen binding to estrogen receptors in vitro, while no such inhibition was observed with testosterone for androgen receptors. The authors conclude that the study observations, together with reported incidences of gynecomastia following exposure to geraniol, strongly suggest that the prostatic hyperplasia-inducing capacity of citral may be due to its estrogenic action. [Note: Citral is formed when geraniol, a monoterpene-alcohol found in lavender essential oil, is oxidized.]