The dose makes the poison

"The dose makes the poison" ( 'only the dose makes the poison') is a proverb intended to indicate a basic principle of toxicology. It is credited to Swiss physician Paracelsus who expressed the following classic toxicology maxim:

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). cite web | url-status=dead | access-date=2022-08-13 | archive-url=https://web.archive.org/web/20110202055026/http://learn.caim.yale.edu/chemsafe/references/dose.html | archive-date=2011-02-02

The principle relies on the finding that all chemicals—even water and oxygen—can be toxic if too much is eaten, drunk, or absorbed. "The toxicity of any particular chemical depends on many factors, including the extent to which it enters an individual’s body." This finding also provides the basis for public health standards, which specify maximum acceptable concentrations of various contaminants in food, public drinking water, and the environment.

The idea also describes the phenomenon in which a poisonous substance, such as digitalis, can be medicinal (digoxin) in small, controlled, doses.