A 55-year-old woman with a history of high blood pressure and chronic obstructive pulmonary disease (COPD) attended her Primary Care clinic after developing sudden, painful red patches on her cheeks and neck, accompanied by a mild fever.

Her medical history included daily smoking (10 cigarettes) and ongoing treatment with enalapril for six years. For her lung condition, she had been using inhaled formoterol for two years. Following a recent worsening of symptoms, her pulmonologist replaced formoterol with a combination of indacaterol and glycopyrronium capsules.

Just two days after starting the new inhaler, the skin reaction appeared. The patient denied using new skincare products, changing her diet, or having cold symptoms, though she had recently been exposed to the sun with proper protection.

Due to the severity and sudden onset of symptoms, she was urgently referred to Dermatology. Specialists advised discontinuing the new inhaler and prescribed oral corticosteroids. Blood tests and a skin biopsy were performed. Within 48 hours, the lesions began to fade, and discomfort decreased. Test results showed elevated white blood cell counts but no infectious cause.

Twenty days later, biopsy results confirmed Sweet syndrome—a rare inflammatory skin condition that can also affect internal organs. It typically presents as painful, red or violet-colored skin plaques, often with fever and increased white blood cells. The exact cause is unknown, but possible triggers include infections, autoimmune diseases, cancer, and certain medications.

Sweet syndrome is more common in women and can be linked to drugs such as antibiotics, antihypertensives, contraceptives, and vaccines. However, no previous cases had been documented involving inhaled indacaterol and glycopyrronium, making this case the first reported in medical literature.

Early treatment with corticosteroids is highly effective, usually resolving symptoms within a week. In rare instances, Sweet syndrome may signal an underlying condition such as cancer, autoimmune disease, or serious infection—making prompt diagnosis and investigation essential.

Key takeaway for healthcare professionals: Even uncommon diseases should be considered in the diagnostic process, particularly when symptoms closely follow a change in medication. Early recognition and referral can prevent complications and lead to faster recovery.