Many generations of children remember the strong, aromatic smell of eucalyptus. Our mothers were quick to bring out the family supply of whatever eucalyptus product was available at the time and liberally slather it on our chests when we were in the throes of a bad cold or had the croup or bronchitis.

While Mom may not have understood the chemical activity that helped us to breathe easier, the relief that eucalyptus provided was enough to continue the practice. Today, there are multiple brand-name products that contain eucalyptus oil for medicinal uses.


Australia is the world’s main producer of eucalyptus oil.1 Also called the “gum tree,” eucalyptus is an evergreen, and its leaves are broad, whitish-green, and waxy. It is the leaves of Eucalyptus globulus that are harvested for the distillation of its essential oil. The active ingredient of eucalyptus oil is 1.8-cineol, or eucalyptol.2


The actual mechanism of action in eucalyptus oil is still unclear. Generally, eucalyptus oil is thought to be anti-inflammatory and antimicrobial. There is some evidence that it can be used as an antifungal agent.3  

One study examined the effect of eucalyptus oil on human monocytes, specifically its ability to stimulate protective macrophage activity.The substance was also studied for its effect on the release of pro-inflammatory cytokines. Eucalyptus oil significantly induced macrophage activation and reduced the release of inflammatory cytokines.4

Steroid-dependent asthma patients were studied to determine the potential for steroid reduction when treated with an oral preparation of eucalyptus oil.5 After randomization, patients’ daily steroid doses were reduced by 2.5mg every three weeks. At the end of 12 weeks, 36% of the patients on the active eucalyptus-oil therapy tolerated an average of 3.5mg/day reduction in oral steroid use while only 7% of the placebo-treated patients were able to decrease their daily dose with an average reduction of 0.91mg/day.

Eucalyptus oil has also been studied for its potential as an antimicrobial. A study of 56 respiratory isolates from 200 symptomatic patients showed definite antimicrobial activity with eucalyptus oil.6 Isolates included Staphylococcus aureus, Streptococcus pyogenes, Streptococcus pneumoniae, and Haemophilus influenzae. With the rise in antimicrobial resistance, a potential new method for treating these infections is welcome news.


This article originally appeared on Clinical Advisor