Drug allergy
Drug allergy | |
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Specialty | Immunology, pharmacology |
A drug allergy is an allergy to a drug, most commonly a medication, and is a form of adverse drug reaction. Medical attention should be sought immediately if an allergic reaction is suspected.
An allergic reaction will not occur on the first exposure to a substance. The first exposure allows the body to create antibodies and memory lymphocyte cells for the antigen. However, drugs often contain many different substances, including dyes, which could cause allergic reactions. This can cause an allergic reaction on the first administration of a drug. For example, a person who developed an allergy to a red dye will be allergic to any new drug which contains that red dye.
A drug allergy is different from an intolerance. A drug intolerance, which is often a milder, non-immune-mediated reaction, does not depend on prior exposure.
Signs and symptoms
Symptoms of drug hypersensitivity reactions can be similar to non-allergic
- Hives
- Itching
- Rash
- Fever
- Facial swelling
- Shortness of breath due to the short-term constriction of lung airways or longer-term damage to lung tissue
- Anaphylaxis, a life-threatening drug reaction (produces most of these symptoms as well as low blood pressure)
- Cardiac symptoms such as chest pain, shortness of breath, fatigue, chest palpitations, light headedness, and syncope due to a rare drug-induced reaction, eosinophilic myocarditis
Causes
Some classes of medications have a higher rate of drug reactions than others. These include
Risk factors
Risk factors for drug allergies can be attributed to the drug itself or the characteristics of the patient. Drug-specific risk factors include the dose, route of administration, duration of treatment, repetitive exposure to the drug, and concurrent illnesses. Host risk factors include age, sex, atopy, specific genetic polymorphisms, and inherent predisposition to react to multiple unrelated drugs (multiple drug allergy syndrome).[3] A drug allergy is more likely to develop with large doses and extended exposure.[citation needed]
People with immunological diseases, such as
Mechanisms
There are two broad mechanisms for a drug allergy to occur: IgE or non-IgE mediated. In IgE-mediated reactions, also known as immunoglobulin E mediated reactions, drug allergens bind to IgE antibodies, which are attached to mast cells and basophils, resulting in IgE cross-linking, cell activation and release of preformed and newly formed mediators.[5]
Most drugs do not cause reactions in themselves, but by the formation of
Types
Drug allergies or hypersensitivities can be broadly divided into two types: immediate reactions and delayed reactions. Immediate reactions take place within an hour of administration and are IgE mediated, while delayed reactions take place hours to weeks after administration and are
Management
Management of drug allergy consists principally of avoidance or discontinuation of the causative drug.
See also
- Adverse drug reaction
- Drug reaction with eosinophilia and systemic symptoms
- Drug intolerance
- Drug tolerance
References
- ^ "Drug Allergy". Mayo Clinic.
- ^ ISBN 9780723436584.
- ^ "Drug Allergy: An Updated Practice Parameter" (PDF). Retrieved 2013-12-02.
- ^ ISBN 978-0-323-08593-9.
- ^ "World Allergy Organization". Retrieved 2013-11-25.
- ^ PMID 30275849.
- ^ PMID 19563988.
- PMID 23282530.