Drug Allergies Flashcards
What are examples of rashes induced by drugs?
morbilliform
hives
photo-sensitive reactions
SJS/TEN
DRESS
toxic epid necrolysis
What is the most common form of drug eruption?
morbilliform
What is another word for measles-like?
morbilliform
What kind of rash is morbilliform?
maculopapular rash
What is the most common drug group to induce morbilliform?
antibiotics
What percentage of new prescriptions cause a drug eruption?
2%
When starting a drug, what is the most common time frame for a drug eruption to present?
1-2 weeks after starting the drug
True or false: it is very common for a drug that has been taken for months or years to cause a morbilliform drug eruption
false
Where do morbilliform drug eruptions tend to first appear? Where will they spread?
trunk
spreads to the limbs and neck
What other symptoms might morbilliform be associated with?
itch
mild fever
What is the most important treatment for morbilliform drug eruptions?
stop the drug
try identify the causative drug
True or false: antihistamines are helpful for morbilliform
false
If the causative drug of morbilliform is stopped, how long can you expect the rash to improve?
improvement in 48 hours and clears in 1-2 weeks
What is itchier; hives or morbilliform?
hives
When should you be really worried about a morbilliform drug eruption?
the presence of blisters and pus-filled lesions
What is the second most common form of drug rash?
hives
What do the vast majority of pharmacists do in most cases of drug rashes?
recommend patients stop the drug and contact their MD
What is the difference between phototoxic reactions and photoallergic reactions?
phototoxic:
-resembles sunburn
-drug activated by sunlight
-fast onset
-clears upon drug clearance from body
photoallergic:
-resembles eczema
-UV rays create an allergen
-longer lasting
-can occur even upon drug clearance
What are the most common drugs that cause SJS?
allopurinol (gout medications)
acetaminophen, ibuprofen, naproxen
sulfa antibiotics
medication for seizures or mental illness
True or false: toxic epidermal necrolysis is far more common than SJS
false
When does SJS start to present itself?
4-30 days following first exposure
-within 8 weeks
What are the symptoms of SJS?
skin pain (most common)
flu-like
usually not itchy
blisters and open wounds
When should you seek an MD for drug rashes?
covering the entire body
high temperature
very painful
blisters or open sores
difficulty breathing or throat tightens
True or false: drug rashes only appear after the first dose
false
can appear after many doses
What can be seen as drug rashes start to resolve?
mild skin peeling
What might it be smart to start indicating on a patient profile when they have a drug rash?
“rash potentially via drug” rather than “drug allergy”
What could happen upon next exposure to a drug that someone previously got a rash from?
no reaction (one off)
same reaction (for a few days)
worse reaction=very RARE
What is the number difference between rashes to ibuprofen compared to allergies to ibuprofen?
10x more rashes
-5% of people get rashes
-0.5% of people are allergic
Describe rash that results from amoxicillin.
morbilliform, erythematous, hives
may occur after 3-14 days of therapy, this rash is not a true allergy
starts on trunk and can spread to the periphery
subsides after 1-2 weeks with continued therapy or 7 days if dc
When is amoxicillin rash more common?
during viral illness (should not be considerd an allergy)
True or false: penicillin allergies can resolve over time
true
Which drug is the poster-boy for SJS?
sulfas
What are key things to keep in mind with a patient who got a rash from a newly started drug?
IF due to drug, most likely morbilliform appearance
IF person was also sick, sickness could be cause of rash
most likely d/c the agent
What are causes of morbilliform rashes?
infectious: measles, 6th disease, strep
drugs: antibiotics, NSAIDs, etc
