Fixed Drug Eruption

Aka: Fixed Drug Eruption, Morbilliform Drug Reaction, Exanthematous Drug Reaction

1. See Also
   1. Adverse Drug Reaction
   2. Life-Threatening Drug-Induced Rashes
   3. Hypersensitivity Reaction
   4. Anaphylaxis
   5. Penicillin Allergy
   6. Gell and Coombs Classification
2. Pathophysiology
   1. Delayed Type IV Hypersensitivity Reaction
   2. Antibody-dependent, cell-mediated cytotoxic response
3. Epidemiology
   1. Of cutaneous drugs eruptions, Morbilliform rash accounts for 80% in adults and 35% in children
4. Causes: Antimicrobials
   1. Antibiotics (most common)
      1. Sulfonamides (e.g. Bactrim) - most common
      2. Tetracycline - most common
      3. Cephalosporins
      4. Macrolides (e.g. Erythromycin, Clarithromycin)
      5. Clindamycin
      6. Fluoroquinolones
      7. Penicillins (e.g. Amoxicillin)
   2. Antifungals
      1. Fluconazole
      2. Ketoconazole
      3. Griseofulvin
   3. Miscellaneous
      1. Antimalarials
      2. Dapsone
5. Causes: Miscellaneous
   1. Cardiovascular agents
      1. Beta Blockers
      2. ACE Inhibitors
      3. Flecainide
   2. Analgesics
      1. Acetaminophen
      2. NSAIDs or Aspirin (common)
      3. Allopurinol
      4. Colchicine
      5. Opiates (e.g. Codeine)
   3. Neuropsychiatric agents
      1. Barbiturates
      2. Gabapentin
      3. Carbamazepine
      4. Lamotrigine
      5. Benzodiazepines
      6. Lithium
   4. Antihistamines
      1. Hydroxyzine
      2. Laratodine
   5. Miscellaneous
      1. Finasteride
6. Risk Factors
   1. Immunosuppression
   2. Childhood Viral Infections
7. Symptoms
   1. Lesion with pruritic or burning pain
   2. Lesion timing after initial exposure
      1. Onset 4 to 21 days after starting medication
   3. Lesion timing after subsequent exposure
      1. Onset within 0.5 to 8 hours (up to 16 hours) after medication ingestion
      2. Lesions recur at same site on reexposure to drug
   4. Systemic Symptoms are rare
      1. Fever, malaise and Nausea may be seen with Drug-Induced Bullous Disease
8. Signs
   1. Lesion onset on the trunk and spreads peripherally
   2. Lesion distribution
      1. Symmetric involvement on trunk and extremities (especially dependent, warm areas)
      2. Face or ears
      3. Genital region
      4. Sacral area
      5. Hands or feet
      6. Spares mucous membranes
   3. Lesion characteristics
      1. Coloration
         1. Pink to dark red
      2. Maculopapular Rash with Annular Lesions
         1. Round erythematous patch with sharp borders
      3. May also present as bullae or ulcers
      4. Hyperpigmentation may occur on healing after withdrawal of causative agent
9. Management
   1. Withdraw suspected medication
   2. Consider Corticosteroids (topical or systemic)
   3. Consider Antihistamine for Pruritus
   4. Observe open lesions for secondary infection
10. Course
    1. Resolves in 7-10 days after medication stopped
11. Complications
    1. Postinflammatory Hyperpigmentation
12. References
    1. Crowson (2003) Am J Clin Dermatol 4:407-28 [PubMed]
    2. Nelson (2022) Am Fam Physician 106(2): 193-4 [PubMed]
    3. Trayes (2018) Am Fam Physician 98(5): 283-91 [PubMed]