drugs
Overview of Adverse Drug Reactions
Introduction
Adverse drug reactions (adverse effects) are any unwanted effects of a drug or medication. In the early 1900s, German scientist Paul Ehrlich described an ideal drug as a "magic bullet." Such a drug would be aimed precisely at a disease site and would not harm healthy tissues. Although many new medications are aimed more accurately than their predecessors, none of them, as of yet, hit the target exclusively. Most medications produce several effects, but usually only one effect—the therapeutic effect—is wanted for the treatment of a disorder. The other effects may be regarded as unwanted, whether they are intrinsically harmful or not. For example, certain antihistamines cause drowsiness as well as control the symptoms of allergies. When an over-the-counter sleep aid containing an antihistamine is taken, drowsiness is considered a therapeutic effect. But when an antihistamine is taken to control allergy symptoms during the daytime, drowsiness is considered an annoying, unwanted effect. Most people, including health care practitioners, refer to unwanted effects as side effects; another term used is adverse drug effect. However, the termadverse drug reactionis technically more appropriate for drug effects that are unwanted, unpleasant,noxious, or potentially harmful. 