The Royal Marsden Hospital Manual of Clinical Nursing Procedures - Lisa Dougherty [529]
Table 13.3 Types of allergic reactions
Type of reaction Result of reaction Example of reaction
Type I – IgE-mediated reactions Urticaria, angio-oedema, anaphylaxis and bronchospasm Anaphylaxis from beta-lactam antibiotic
Type II – IgG/M-mediated cytotoxic reaction Anaemia, cytopenia and thrombocytopenia Haemolytic anaemia from penicillin
Type III – IgG/M-mediated immune complexes Vasculitis, lymphadenopathy, fever, arthropathy and rashes
Can also be known as serum sickness
Serum sickness from antithymocyte globulin
Type IV – delayed hypersensitivity reactions Dermatitis, bullous exanthema, maculopapular and pustular xanthemata Contact dermatitis from topical antihistamine
Beijnen and Schellens (2004), Riedl and Casillas (2003).
There are many risk factors that increase the likelihood of having an allergic reaction. These can be split into those that are specific to the patient and those that are specific to the drug.
The patient-related factors include the following.
Immune status: previous reaction to the same or related compound.
Age: younger adults are more likely to have allergic reactions than infants or the elderly.
Gender: women are more likely than men to suffer cutaneous reactions.
Genetic: atopic predisposition is more likely to result in a severe reaction and genetic polymorphisms may predispose to drug hypersensitivity, for example G6PD deficiency, slow acetylators.
Concomitant disease: viral infections such as HIV and herpes are associated with an increased risk of allergic reactions; cystic fibrosis is associated with an increased risk of allergic reactions to antibiotics, which is though to be due to the prolonged use in this group of patients.
(Mirakian et al. 2009)
The drug-related risk factors include the following.
Drug chemistry: some drugs are more likely to cause reactions than others. These are high molecular weight compounds, for example dextran and insulin. Also, drugs that bind to proteins called haptens, forming complexes that can cause an immune response, for example beta-lactam antibiotics.
Route of administration: the topical route is most likely to cause an allergy, with the oral route being least likely. The intramuscular route is more likely than the intravenous route.
Dose: a large single dose is less likely to cause a reaction than prolonged or frequent doses.
(Mirakian et al. 2009)
Although the incidence of true allergic drug reactions is low, the potential morbidity and mortality related to these reactions can be high, so it is important that drug allergies are accurately diagnosed and treated. The first step towards an accurate diagnosis is a detailed history (Mirakian et al. 2009). Guidance on what information should be collated is detailed in the BSACI drug allergy guidelines which can be found on the website at www.bscaci.com and includes the following.
Detailed description of reaction:
– symptom sequence and duration
– treatment provided
– outcome.
Timing of symptoms in relation to drug administration.
Has the patient had the suspected drug before this course of treatment?
– How long had the drug(s) been taken before onset of reaction?
– When was/were the drug(s) stopped?
– What was the effect?
Witness description (patient, relative, doctor).
Is there a photograph of the reaction?
Illness for which suspected drug was being taken, that is, underlying illness (this may be the cause of the symptoms, rather than the drug).
List of all drugs taken at the time of the reaction (including regular medication, OTC and ‘alternative’ remedies).
Previous history:
– other drug reactions
– other allergies
– other illnesses.
(Mirakian et al. 2009)
This guideline also gives details on further investigations which may be required in order to accurately diagnose an allergic reaction (Box 13.7).
Box 13.7 Treatment of acute drug reaction
An acute drug reaction must be treated promptly and appropriately.
Stop the suspected drug.
Treat the reaction.