In medical practice, small treatment adjustments often improve patient outcomes. But occasionally, a simple change can reveal something unexpected. Such was the case for a 55-year-old woman with COPD. For years, she was stable on enalapril and a formoterol-based inhaler. When her lung function declined, her pulmonologist prescribed a new inhaler containing indacaterol and glycopyrronium.
Within 48 hours, she developed painful red plaques on her face and neck, along with fever. With no new products or illnesses to explain the reaction, she was referred to dermatology. Blood tests ruled out common causes, and a skin biopsy confirmed Sweet syndrome—a rare immune-mediated condition. Discontinuing the inhaler and starting corticosteroids brought rapid improvement.
Sweet syndrome, first described in 1964, typically presents with sudden, painful lesions, fever, and elevated neutrophils. Known triggers include infections, cancers, autoimmune disorders, and systemic medications. However, this appears to be the first case linked to an inhaled therapy.
The case underscores vital lessons: remain vigilant after medication changes, consider rare reactions, and act quickly with treatment. Even inhaled drugs, often considered safer, can produce unexpected immune responses.
