ABSTRACT
An adverse effect is defined as an unwanted and harmful reaction resulting from drugs used therapeutically, prophylactically, diagnostically or to alter physiological functions.
Drugs exert their effects wherever there are substrates or receptors that are influenced by them. This makes it possible for both desired and undesired effects to occur. Ideally, drugs should have a high specificity, that means an effect on the minimum number of different receptors and organs. High specificity allows for a therapeutic effect which largely avoids adverse effects. Effects due to misuse, or which occur as a result of a planned overdose, are not regarded as adverse effects.
