doTERRA Eucalyptus essential oil is sourced from Eucalyptus radiata leaves harvested in Australia, where growing conditions make the oil particularly rich in eucalyptol. Eucalyptol produces a cooling, soothing vapor when inhaled or applied topically. This vapor is beneficial to the airways when inhaled. When you feel under the weather, diffuse Eucalyptus, or rub a couple drops onto your chest, to promote feelings of open airways.