Eucalyptus Oil Worst Irritant No known benefits Eucalyptus Oil description Fragrant plant oil whose active constituents are found in the leaves and in the oil obtained from them. The oil has benefits for skin, but is also a potent skin sensitizer due to its chemical components. Truly a mixed bag, this oil, like rosemary oil, has benefits and risks. Low amounts of eucalyptus oil do not seem to pose a risk of sensitivity in the general population, but its fragrance components are known sensitiser.