Low-dose venlafaxine-induced erythema multiforme: a case report

Venlafaxine, a serotonin-norepinephrine reuptake inhibitor, is commonly prescribed for depressive and anxiety disorders, with a safety profile comparable to selective serotonin reuptake inhibitors. Although venlafaxine's adverse effects are generally mild, serious cutaneous reactions such as erythema multiforme are exceedingly rare.

To the best of our knowledge, we report the first known case of venlafaxine-induced erythema multiforme in a 74-year-old Iranian male with generalized anxiety disorder, who developed an erythematous, papular rash after initiating low-dose venlafaxine. The patient's comorbidities and polypharmacy increased his risk for hypersensitivity, and the development of delayed skin lesions aligned with drug-induced erythema multiforme. Differential diagnoses, including drug reaction with eosinophilia and systemic symptoms, Stevens-Johnson syndrome, and viral exanthems, were ruled out on the basis of lesion morphology, distribution, and absence of systemic symptoms. Although histopathologic confirmation was not obtained, the rapid resolution of symptoms following venlafaxine discontinuation supports the diagnosis of drug-induced erythema multiforme.

This case highlights the complexities of managing cutaneous drug reactions in elderly patients with multiple medications and emphasizes the importance of vigilance for rare adverse reactions with psychiatric medications, particularly in high-risk populations. Prompt recognition and withdrawal of the offending agent are crucial to prevent progression to severe drug reactions such as Stevens-Johnson syndrome or toxic epidermal necrolysis. Prompt drug discontinuation can prevent progression to severe reactions. This case also underscores the need for further research into the mechanisms and management of rare drug-induced reactions, particularly in elderly patients with complex medical histories.