Essential oils may smell great, but orally ingesting them can cause all sorts of problems. Recent studies have found that essential oil poisonings are becoming more frequent and more severe in Europe and the US, and the latest figures from Australia show a similar trend Down Under.

Appearing in the Medical Journal of Australia, the new study analyzes data from the New South Wales Poisons Information Centre (NSWPIC), which deals with about half of all calls to Poisons Informations Centres across the country. Between July 2014 and June 2018, the facility recorded a total of 4,412 cases of essential oil poisoning, with around two-thirds of these involving children under the age of 15. The number of calls rose from 1,011 in 2014-15 to 1,177 in 2017-18, representing a considerable 16 percent increase.

Essential oils are volatile chemical compounds (meaning they evaporate at low temperatures) that are extracted from plant material via a distillation process that commonly involves steaming. Their name refers to the fact that they contain the essence of the plant's fragrance, and as such are known for their pleasant scent.

Used in perfumes, soaps, incense burners, and as aromatherapy aides, essential oils are said to benefit overall health by relaxing the nervous system. However, some suppliers also suggest applying the oils topically or even ingesting them orally, which the study authors strongly warn against.

Essential oils can “cause severe toxicity when ingested, the risk depending on the oil used; the onset of toxicity can be rapid, and small quantities (as little as 5 mL) can cause life-threatening toxicity in children,” they explain in their report.

“Clinical effects include vomiting, central nervous system depression or excitation, and aspiration pneumonitis.”

Some essential oils can also mess with the body’s hormonal balance, with studies showing that both lavender and tea tree oil contain compounds that mimic oestrogen and inhibit testosterone. This has led to a small number of cases of prepubertal gynecomastia, whereby young boys developed enlarged breasts after repeatedly applying these oils to their skin. In all recorded cases, symptoms disappeared once the boys stopped using the oils.

Breaking down the data, the study authors explain that of those who contacted NSWPIC, around 80 percent had unintentionally ingested essential oils after mistaking the bottle for something else, such as cough syrup, or were the result of therapeutic error (13 percent). However, 105 people – making up 2.4 percent of the total – had deliberately taken the oils, following misinformation regarding the safety and efficacy of doing so.

“Flow restrictors and child-resistant closures would be desirable, but containers are only required to have such closures when the essential oil volume exceeds 15 millilitres,” explain the researchers. Given that as little as 5 millilitres is enough to produce severe toxicity, the authors insist that current regulations are inadequate to ensure the safety of children.