Why do some people still experience side effects after a compound has been found safe in animals?
Even after years of intensive study, and a comprehensive evaluation of all the data, medicines sometimes cause unexpected side-effects in general use. Those who campaign against animal research frequently cite such side-effects as an argument against animal testing but this is to misunderstand the careful step-by-step nature of the research process. No one expects animal studies to provide all the necessary information and final decisions are never made on the basis of animal tests alone. Rather, they enable researchers to move as close as possible to the human situation before a new medicine is tested and used in people. All medicines approved by the FDA, even those later found to have unexpected side effects, passed all the testing stages including non-animal, animal and human research. No amount of testing can guarantee to find all of the possible side-effects for every person who may take a medicine. A reaction which occurs at a rate of 1 in 100,000 people or even at a higher rate
