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exanthematous drug eruption (morbilliform exanthem)
Morbilliform exanthem due to drug reaction.
Etiology:
1) amoxicillin (5%)
2) Bactrim (3%)
3) ampicillin (3%)
4) cephalosporins (2%)
5) semisynthetic penicillins (2%)
6) erythromycin (2%)
7) penicillin G (2%)
8) quinidine (1%)
9) cimetidine (1%)
10) allopurinol (1%)
11) barbiturates
12) indapamine
13) methyldopa
14) phenytoin
15) captopril
16) gold
17) carbamazepine
18) sulfonamides (including diuretics)
19) NSAIDs
Epidemiology:
1) common in geriatric patients due to polypharmacy
2) most common type of cutaneous drug eruption
Pathology:
- type 4 hypersensitivity
Clinical manifestations:
1) commonly occurs 1-3 weeks after initiation of drug
- may occur sooner if exposure is recurrent [2]
2) may occur at any time or with change is dose
3) erythematous macules or papules which may become confluent
4) symmetric distribution on trunk & extremities
5) palms & soles generally spared [2]
5) pruritus variable
- sudden, itchy, resembles measles
6) lymphadenopathy common
Laboratory:
- complete blood count may show eosinophilia
Differential diagnosis:
- pseudoallergies, drugs that release histamine
- photosensitivity
- other dermatitis
- DRESS
- leukocytoclastic vasculitis
Complications:
- may become generalized exfoliative erythroderma
Management:
1) discontinue offending agent
2) supportive care
a) topical antipruritics containing menthol
b) antihistamines
1] H1 antagonists
a] hydroxyzine (Atarax, Vistaril)
b] diphenhydramine (Benadryl)
2] H2 antagonists
a] cimetidine (Tagamet)
b] ranitidine (Zantac)
c) medium-potency topical glucocorticoids [2]
d) short prednisone taper (1 week)
Specific
drug eruption with eosinophilia & systemic symptoms
General
exanthem
drug eruption; drug rash
type 4 hypersensitivity; T-cell-mediated (delayed) hypersensitivity
References
- Harrison's Principles of Internal Medicine, 13th ed.
Companion Handbook, Isselbacher et al (eds), McGraw-Hill
Inc. NY, 1995, pg 829-39
- Medical Knowledge Self Assessment Program (MKSAP) 11, 17, 19
American College of Physicians, Philadelphia 1998, 2015, 2022
- Takahashi S, In: UCLA Intensive Course in Geriatric Medicine
& Board Review, Marina Del Ray, CA, Sept 29-Oct 2, 2004
- Prescriber's Letter 14(10): 2007
Management of common skin diseases
Detail-Document#: 231011
(subscription needed) http://www.prescribersletter.com
- Stern RS. Clinical practice.
Exanthematous drug eruptions.
N Engl J Med 2012 Jun 29; 366:2492
PMID: 22738099
http://www.nejm.org/doi/full/10.1056/NEJMcp1104080
- Kroshinsky D
Adverse cutaneous reactions to medications
Clin Dermatol. 2020 Nov-Dec;38(6):605-606
PMID: 33341194