Herbal drugs rely on effects that have evolved over long periods, but they have uncertain strength, while medical versions of those drugs are more predictable.
Herbal drugs rely on chemical effects that evolved over long periods to be biologically active in some way, and just happen to also affect some other condition.
The study of past use of plant medicines is ethnobotany. It involves identifying those plants which experimentation has identified as effective against disease.
In 1785 William Withering published 'An Account of the Foxglove and Some of Its Medical Uses', introducing the traditional herb digitalis as a medical drug.
In 1809 Benjamin Silliman and a partner opened the first two soda water fountains in New York City, promoting the drink as a remedy against yellow fever.
In 1941, Selman Abraham Waksman coined the term 'antibiotic' to describe compounds produced by microorganisms which are able to kill bacteria.
Antibiotics have evolved naturally to combat other life forms, mostly in the soil, on the moist skin of frogs, or in other places where competition is intense.
Antibiotics are selective poisons that kill some sorts of bacteria which lack resistance, but it should not be assumed that they do not harm us as well.
Many frogs secrete antibiotics on their skin, an important adaptation in an animal that lives mostly in damp places. Some frogs also secrete toxins.
Many living things living in damp and moist conditions produce antibiotics, chemicals that limit the growth of bacteria on the organism producing them.
Antibiotics are effective against some bacteria. They are selective poisons that kill bacteria: they are more poisonous to bacteria than to our cells.
Many bacteria are resistant to some antibiotics, and given time and enough exposure, especially in small doses, can develop resistance to any known antibiotic.
The development and spread of antibiotic resistance is favoured by uncontrolled use of antibiotics in medicine and agriculture and by horizontal gene transfer.
Virus diseases cannot be treated with antibiotics, but a great deal of waste of antibiotics goes on when they are prescribed for viral illnesses.