Cutaneous drug reactions Flashcards
Most common types of cutaneous drug reactions
- Maculopapular
- Urticarial
- and fixed drug eruptions
Most common time frame for onset of drug eruption
Usually within 1-2 weeks of starting drug
Maculopapular drug eruptions
Difficult to distinguish from viral exanthems, often pruritic, start on trunk and spread out symmetrically (hands and soles usually spared)
Ampicillin drug rashes
Two types: 1) Urticarial and 2) Maculopapular. Okay to give ampicillin/other penicillins to patients with history of maculopapular rash but NOT urticarial
MCC of urticarial drug eruptions
Aspirin, penicillin, and blood products
MCC of morbilliform drug eruptions
Ampicillin, amoxicillin, Bactrim, and allopurinol
Three mechanisms of drug-induced urticaria
- Anaphylactic and accelerated reactions
- Nonimmunologic histamine release
- Serum sickness
MCC of anaphylactic/accelerated reactions
Penicillins. Can investigate vis skin testing. Only 5% cross reactivity between patient allergic to penicillins and cephalosporins. Rxn within minutes to hours
Serum sickness drug rxn timeline
Usually see urticaria 4-21 days after drug ingestion. Get systemic signs.
NonIgE Induced urticaria
Common with aspirin and NSAIDs. Urticaria frequently appears on face first and spreads caudally. Antihistamines not as effective in treating
Nonimmunologic histamine releasers
Things that make you itch via mast cells releasing histamine: opioids, lobster, polymyxin B, strawberries
DRESS Syndrome Etiology
MCC of mortality is fulminant hepatitis
Onset 2-6 weeks after drug administration
MCC are anti-convulsants and sulfmonamides (Dapson, sulfasalazine)
DRESS syndrome clinical presentation
Begins with pruritus and fever followed by morbilliform rash
Erythema Multiforme and TEN
Reactions occur on skin and mucous membranes. EM usually presents with targetoid lesion with central duskiness (can also see it in association with mycoplasma or herpes infxn)
MCC death in TEN is fluid loss
MCC are sulfonamides, NSAIDs, and anticonvulsants
Acute generalized exanthematous pustulosis (AGEP)
Occurs acutely after drug administration, multiple non-follicular sterile pustules
MCC are CCBs, NSAIDs, anti-convulsants, beta-lactam and macrolide antibiotics
Must rule out generalized pustular psoriasis
Other patterns of drug eruptions
Acneiform (think oral steroids/abuse of anabolic steroids as possible causes)
Eczema (variant known as baboon syndrome)
Photosensitive (phototoxicity vs. photoallergy)
Small vessel necrotizing vasculitis
Lymphomatoid
Fixed Drug eruption
Single/multiple Red plaques or blisters that recur at same site with each exposure (~ around 2 hrs with refractory period)
Specific common fixed drug eruptions
Tetracyclines and co-trimazole (lesions on glans penis)
Pseudoephedrine (non-pigmented lesion)
Tx of fixed drug eruption
Topical steroids
Blistering drug reactions
MCC are NSAIDs
Can look like linear IgA dermatosis, pemphigus/BP, or pseudoporphyria
Exfoliative erythroderma
Can be seen not only with drug rxns but also CTCL, PRP, and psoriasis
Lichenoid drug reaction
Look like generalized lichen planus and latent period between drug administration and reaction is between 3 weeks and 3 years
MCC are gold and antimalarials
Lupus like Drug eruption MCC
Hydralazine, procainamide, isoniazid, methyldopa, quinidine, minocycline, and chlorpromazine.
Association with anti-TNF drug also reported
Clinical presentation of drug induced lupus
Milder sx but still see arthralgias, fever, malaise, etc
Cutaneous signs much less common than in SLE although there is an SCLE variant
Rxn is dose related
