Eucalyptus oil is commonly used in respiratory conditions like pharyngitis, bronchitis, sinusitis, and asthma, the medicinal ingredients can easily be delivered to the airways through steam inhalation. Many of the antimicrobial actions come from the constituents 1,8‑cineole, limonene, and alpha-pinene. Research has shown these to be protective against Haemophilus influenzae virus as well as Staphylococcus spp. and Streptococcus spp. bacteria, which are all common causes of respiratory tract infections. Eucalyptus oil does have a drying action on the mucous membranes, so if you inhale too much, it may cause mild irritation to these surfaces.

Eucalyptus has also been shown to improve working memory and focus. One study exhibited the combination of peppermint and eucalyptus oils beneficial for memory. This therapeutic tandem also proved to promote a relaxed mental state.