Around 1520, the Swiss physician and alchemist Paracelsus began to fundamentally challenge the established medical traditions of his era. At a time when European medicine was dominated by the classical teachings of figures such as Galen and Hippocrates, which focused on the balance of bodily humours, Paracelsus advocated for a radical shift towards chemical therapeutics. He argued that the natural world contained specific chemical substances that could be harnessed to treat disease, effectively laying the groundwork for the development of modern pharmacology.

Central to his philosophy was the revolutionary concept that the difference between a remedy and a poison lies solely in the dose. This principle, which remains a cornerstone of toxicology and medicine today, encouraged practitioners to move away from purely theoretical explanations of illness and towards a more empirical, observation-based approach. By prioritising the direct study of chemical reactions within the body, he sought to replace the rigid, centuries-old reliance on ancient texts with a more practical understanding of how substances interact with human physiology.

Although his ideas were met with significant controversy and resistance from the medical establishment of the time, his work proved instrumental in shifting the trajectory of European healthcare. By championing the use of minerals and metals in medicine, he helped to legitimise the role of chemistry in the healing arts. His influence gradually eroded the dominance of classical dogma, paving the way for the scientific advancements that would eventually define the field of pharmaceutical medicine.

• Challenged the traditional reliance on classical medical authorities.
• Promoted the use of chemical remedies over herbal or humoural treatments.
• Established the foundational principle that the dose determines the effect of a substance.
• Encouraged an empirical approach to medical practice and observation.
• Shifted European medicine towards the development of chemical therapeutics.