Drug Allergy Flashcards
What are the 4 different drug reactions which can occur?
Immediate
Delayed
Idiosyncratic= off-target effect
Side effects
What is the time frame for a reaction to be classified as immediate?
What might a patient present with?
<1hr Urticaria/angioedema D+V Tachy HypoTN Wheeze Hoarse voice (laryngeal swelling) Confusion/LOC
What is the time frame for a delayed reaction?
How might a person typically present?
> 1hr i.e. likely to have occurred after several doses so need to ask about chronological association between symptoms and dosage
Variety of rashes Itching Unexplained fever GI upset Arthralgia Myalgia
What are examples of idiosyncratic reactions?
How might these reactions present?
Steven Johnsons syndrome
Toxic epidermal necrolysis
Haemolysis
Presentation:
- high fevers
- exfoliating rash
- mucous membrane= oral-genital
- haematological problems
- liver problems
What is the most common drug allergy?
Penicillin -can’t give any drugs in this class once had reaction
What needs to be included as part of drugs reaction?
Drugs at the time:
- drug name
- date started
- time to reaction from starting dose
Concomitant medication
-antihistamines + steroids
Previous hx
Details of reaction
-any evidence of systemic reaction= decrease BP/tachy/bronchospasm
What is the approach to managing a drug allergy?
Depends on kind of allergy:
IgE mediated
- stop drug
- monitor for signs of anaphylaxis
Idiosyncratic
- stop drug
- supportive treatment
- never give the drug again
Non-IgE mediated:
- mild/moderate= consider continuing
- severe= stop drug
When can desensitisation be considered?
Can be considered in IgE mediated drug reaction when the drug is essential and the benefits of taking the drug outweigh the harms of reaction
NOT VERY COMMON
