Desvenlafaxine-induced myositis with positive medication rechallenge

To the Editor: A 23-year-old woman presented to the emergency department with bilateral pain, swelling and loss of power in her upper arms, which had started that morning. She had no history of significant trauma. Her medical history was significant for Wolff–Parkinson–White syndrome, diagnosed 3 weeks earlier at the same institution, and mild depression, diagnosed 8 months earlier, for which she had been taking desvenlafaxine (50 mg daily for the first 4 months, and then 100 mg daily until her presentation). She had no known adverse drug reactions.