Volume 52, Issue 6, June 2023


Brendon Evans   
doi: 10.31128/AJGP-06-23-1234e   |    Download article
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Paracelsus – Father of toxicology, brother of general practice

‘Every physician must be rich in knowledge, and not only of that which is written in books; his patients should be his book, they will never mislead him.’

– Paracelsus, 15651

Paracelsus is a historical medical name that is not taught in modern medical education (or at least not in my own). Yet the Swiss physician is often referred to as the ‘father of toxicology’ and the ‘Martin Luther of medicine’.2 He espoused patient-centred care, broadmindedness and holistic evidence-based medicine – in other words – the principles of general practice.

Paracelsus significantly progressed medical practice. He was among the vanguard marrying science to medicine and the first to apply chemistry – although in its embryonic renaissance form.3 He was also the first to express what is now referred to as the threshold and no-adverse effect level concepts – central principles of toxicology, as illustrated by the famous statement, ‘All things are poison and nothing is without poison; only the dose makes a thing not a poison.’3 He rejected the previously accepted model of disease based on the four humours, and was perhaps the first occupational physician describing illness patterns among miners.4

Itinerant for most of his life, Paracelsus believed that experience and open-mindedness were keys to understanding. ‘The universities do not teach all things,’ he wrote, ‘so a doctor must seek out old wives, gypsies, sorcerers, wandering tribes, old robbers, and such outlaws and take lessons from them. A doctor must be a traveler.…Knowledge is experience’.5 He espoused the principles of patient-centred care, as illustrated by the headline quotation. He opened his lectures to all, not just paying students, and taught in German, the common language, not Latin,6 demonstrating his belief in the dignity of the individual and a rejection of classism.

Australian general practice has much in common with Paracelsus. We are found in the city, the outback, the mine, the sporting field and the barracks. Our treatments are scientific, and our actions evidence-based. We provide care regardless of socioeconomic class or station. We think broadly, try emerging therapies and teach without reserve. Our connection to patient environment and lived experience are the foundation of both our insight and our impact.7 These shared values and processes place general practice alongside one of the legends of medical history.

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  1. Paracelsus, Das Buch Paragranum (1565); SamtlicheWerke, I viii 70; English translation from Paracelsus: Selected writings, edn. Jolande Jacobi, trans. Norbert Guterman, 2nd edn. New York: Pantheon, 1958; p.50. Search PubMed
  2. Bynum B. Does Paracelsus deserve a place in the medical pantheon?. The Lancet 2006; 367(9520): 1389–90. Search PubMed
  3. Grandjean P. Paracelsus revisited: The dose concept in a complex world. Basic Clin Pharmacol Toxicol 2016;119(2):126–32. doi: 10.1111/bcpt.12622. Search PubMed
  4. Whysner J. 4. Mining and the beginnings of occupational medicine. The alchemy of disease: How chemicals and toxins cause cancer and other illnesses. Columbia University Press, 2020; p. 33–41. Available at [Accessed 31 March 2023]. Search PubMed
  5. Hargrave JG. Paracelsus. Encyclopedia Britannica, 2023. Available at [Accessed 31 March 2023]. Search PubMed
  6. Michaleas SN, Laios K, Tsoucalas G, Androutsos G. Theophrastus Bombastus Von Hohenheim (Paracelsus) (1493–1541): The eminent physician and pioneer of toxicology. Toxicol Rep 2021;8:411–14. doi: 10.1016/j.toxrep.2021.02.012. Search PubMed
  7. Evans B. More than what we prescribe. Aust J Gen Pract 2023;52(4):167. doi: 10.31128/AJGP-04-23-5678e. Search PubMed

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