Understanding adverse drug reactions and drug allergies: principles, diagnosis and treatment aspects.

Adverse Drug Reactions (ADRs) and drug allergies- as a subset of ADRs- make a significant public health concern, complicating 5 to 15% of therapeutic drug courses. They may result in diminished quality of life, increased physician visits, health care costs, hospitalizations, and even death. The incidence of serious ADRs in hospitalized patients was estimated to be 6.7% and for fatal ADRs to be 0.32%, so recognizing and taking action on ADRs is an important aspect of medication management. Allergic reactions to drugs refer to those ADRs that involve immune mechanisms which account up to 15% of ADRs and can be identified as being a type I through IV immune reaction that the most common immunologic mechanism is IgE-mediated- type I reaction. Clinical manifestations of allergic reactions range from pruritus and rash to serious reactions such as systemic anaphylaxis and cardiovascular emergencies and they are responsible for 2-3% of hospitalized patients. Health professionals should be aware of the ADRs presenting clinical features and the risk factors and should be able to differentiate between allergic and non-allergic adverse drug reactions. This will lead to increased opportunities to review drug selection and prescribing practices affecting patients' outcome. This article will review the definition and estimated incidence, the features, classification and types of ADRs and drug allergies and related patents. It will highlight the role of detecting, reporting, and assessing suspected ADRs and drug allergies in the most clinically relevant drugs group. Priorities in the evaluation and management of the conditions of patients who have experienced allergic and non-allergic drug reactions also will be discussed.