Question: who said the poison is in the dose?
Answer: Paracelsus, credited to Paracelsus

'' The dose makes the poison '' ( Latin : sola dosis facit venenum ) is an adage intended to indicate a basic principle of toxicology . It is credited to Paracelsus who expressed the classic toxicology maxim '' All things are poison and nothing is without poison ; only the dose makes a thing not a poison . '' This is often condensed to : '' The dose makes the poison '' or in Latin , '' Sola dosis facit venenum '' . It means that a substance can produce the harmful effect associated with its toxic properties only if it reaches a susceptible biological system within the body in a high enough concentration ( i.e. , dose ) .