Dennis Considen (died 1815) was an Irish-born surgeon, best known for his pioneering role in the use of Australian native plants for pharmaceutical use, especially eucalyptus oil, which he used to treat the convicts.
In November 1788 Considen proclaimed himself to English colleague, Dr Anthony Hamilton, as the colony's pharmaceutic pioneer: "...if there is any merit in applying these & many other simples[sic] to the benefit of the poor wretches here, I certainly claim it, being the first who discovered & recommended them.".
[3][4] The Australian botanist, Joseph Maiden, expressed the opinion that Considen deserves credit for being the first person to recognize the medicinal value of eucalyptus oil extracted from E. piperita found growing on the shores of Port Jackson.
[7] In November 1791, after a period on Norfolk Island working with fellow Irish surgeons D'Arcy Wentworth and Thomas Jamison, Considen returned to Sydney.
Considen graduated as a Doctor of Medicine on the 24 June 1804, with a thesis entitled De Tetano, in which he refers to his discovery of eucalyptus oil.