II. Causes: Infections
- Idiopathic (50%)
- However, up to 90% of Erythema Multiforme Minor cases are thought due to infections
-
Herpes Simplex Virus (>50%)
- Occurs 10 days after acute eruption, and resolves over a 2 week period
- HSV may be cause even without active lesions
- Typically associated with HSV-1, but HSV-2 can also cause Erythema Multiforme
-
Mycoplasma pneumoniae
- Second most common cause (esp. children)
- Other infections
III. Causes: Drug Sensitivity
- Background
- Occurs 1-3 weeks after intake
- Highest risk with higher doses and rapid drug introduction
- Most common cause of erythema mutiforme major
- Contrast with Erythema Multiforme Minor which is typically caused infections (esp. HSV, Mycoplasma)
- Medications cause 50% of Stevens Johnson
- Medications cause 90% of Toxic Epidermal Necrolysis)
- Most common with NSAIDS, antiepileptics and Antibiotics
- NSAIDs (esp. Ibuprofen)
-
Antibiotics
- Sulfonamides (e.g. Septra)
- Trimethoprim-Sulfamethoxazole (Bactrim) is the most common cause of Erythema Multiforme Major
- Risk of Erythema Multiforme Major with Trimethoprim-Sulfamethoxazole is up to 40 fold higher in HIV
- Penicillins
- Erythromycin
- Nitrofurantoin
- Tetracyclines
- Ciprofloxacin
- Sulfonamides (e.g. Septra)
- Antiepileptics
- Vaccinations (low overall percentage risk given the very large number of annual Immunizations)
- Miscellaneous Medications
- Acetaminophen
- Phenothiazines
- Bextra (FDA black box warning)
- Allopurinol
- Candesartan (Atacand)
- Metformin (Glucophage)
- TNF-alpha inhibitors (e.g. Adalimumab or Humira)
- Checkpoint Inhibitors (e.g. Pembrolizumab)
- Bupropion (Wellbutrin)
- Statins
- Corticosteroids
IV. Causes: Miscellaneous Causes
- Food Allergy
- Autoimmune Conditions
- Neoplasm
- Associated with Leukemia, Lymphoma
- Solid organ neoplasms (Renal Cell Carcinoma, gastric adenocarcinoma) may cause persistent and refractory cases
- May also be associated with Radiotherapy
- Conditions in Women
- Pregnancy
- Menstruation