It is no doubts that the word "poison" is mostly attributed to anything that causes harm or is lethal to the human body. We live in a world full of industrial and pharmaceutical everyday products like body lotions and creams, beauty kits and nail polish remover, TEFLON coated non-stick materials, insecticides and some important drugs we take . The demarcation between a drug and a posion was bought to light by Doctor Paracelsus,a Swiss-German physician.
He stated in German,and the modern translation of his dictum was what makes something a poison or not. His statement is upheld as a basic principle of toxicology in the field of Pharmacology and medicine.
“What is there that is not poison? All things are poison and nothing is without poison. Solely the dose determines that a thing is not a poison."
—Paracelsus, 1538
How profound it is to think that in the 16th century, Dr. Paracelsus encouraged the use of minerals and metal as a therapeutic agent in treating diseases. Concerns where however raised about his idea of using minerals to heal being too "toxic" ,which lead to his statement about what made a posion. This means that even if the most harmless minerals or chemical compound like water, sodium chloride (NaCl) is to be in excess in the body,it becomes toxic and functions like a poison.
Looking at Paracelsus classic quotes,we can paraphrase as related to drugs and poison that " Every drug is a potential poison at high dose and every poison is a potential drug at low doses.
The dosage of a substance determines its toxic effect. Take for example the excessive intake of acetaminophen (paracetamol). It's can lead to acute liver failure due to the formation of a toxic metabolite of the liver breaking down paracetamol. Paracetamol as we know is a cheap,easy to use,effective Pain-killer that have therapeutic benefits. However,it can lead to paracetamol posion when taken at high dose,about 15g or more per day.
Since we now know that only the dose makes the poison as in case of therapeutic drugs,high doses. Let's look at certain poison being potential drugs a very low controllable dose. Take for example the use of mercury a highly poisonous substance. Mercury is used as a medicinal agent to tackled certain skin disease when combined with other compound like chlorine due to its antifungal and antibacterial properties .
In context,while we do not ignore the potential harm of poisons used as a medicinal agent under very small controllable agent, toxicity overtime and complex affecting factors has become an issue. Hence mercury is strictly regulated in use for treatment of which it's applied when the benefits outweigh the risks.
Reference:
Basic Clinical Pharmacology Toxicology. Author manuscript; available in PMC: 2017 Aug 1.
Published in final edited form as: Basic Clin Pharmacol Toxicol. 2016 Jun 24;119(2):126–132. doi: 10.1111/bcpt.12622
Assessed and Endorsed by the MedReport Medical Review Board