🩺 Unusual Case of Sweet Syndrome Triggered by New Inhaler Therapy in Primary Care


Patient Profile:

  • Age: 55-year-old female
  • Medical History: Hypertension, stable COPD
  • Baseline Medications: Enalapril, formoterol inhaler (long-standing use)

Clinical Change:

Due to declining lung function, her pulmonologist transitioned her from formoterol to a dual bronchodilator combination: indacaterol/glycopyrronium (a long-acting beta-agonist + anticholinergic).

Presentation:

Just 48 hours after starting the new inhaler, she developed:

  • Rapid onset of tender, bright erythematous plaques on the face and neck
  • Mild fever (37.9°C / 100.2°F)
  • No joint pain, respiratory worsening, or mucosal involvement
  • Denial of new cosmetics, dietary changes, or illness
  • Recent sun exposure with proper protection (SPF 50+)

She sought care in primary care, concerned about possible infection or allergic reaction.

🧪 Diagnostic Workup

Complete Blood Count (CBC)
Normal WBC, mild neutrophilia
Inflammatory Markers
Elevated CRP and ESR
ANA, ANCA, RF
Negative
Throat swab & blood cultures
No evidence of infection
Skin Biopsy
Dense neutrophilic infiltrate in dermis, no vasculitis — consistent with Sweet syndrome

✅ Diagnosis: Drug-induced Sweet syndrome, likely triggered by the new inhaler therapy.

💊 Why This Case Stands Out

While there are documented cases of Sweet syndrome linked to systemic medications, this may represent one of the first reported instances associated with an inhaled dual bronchodilator — specifically indacaterol/glycopyrronium.

Although neither component has been definitively tied to Sweet syndrome before, both are pharmacologically active and absorbed systemically to some degree.

🔬 Mechanism Hypothesis:
The rapid onset suggests an immune-mediated hypersensitivity reaction — possibly through cytokine activation or neutrophil recruitment triggered by drug components.

✅ Management & Outcome

Immediate steps taken:

  1. Discontinued the new inhaler
  2. Reinstated previous regimen (formoterol)
  3. Prescribed oral prednisone (40 mg/day) for five days, then tapered

Result:

  • Skin lesions resolved within 72 hours
  • Fever subsided
  • No recurrence at 3-month follow-up
  • Patient managed COPD effectively on alternative therapy

🩺 Alternative inhalers were considered, with close monitoring if future changes are needed.

🚨 Key Takeaways for Clinicians

✅Monitor closely after inhaler changes
Even "routine" switches can have rare side effects
✅Consider Sweet syndrome in acute dermatoses
Especially with fever and neutrophilia, even without systemic drugs
✅Biopsy is key
Differentiates from cellulitis, vasculitis, or erythema multiforme
✅Early discontinuation improves outcome
Symptoms often resolve quickly once trigger is removed
✅Document thoroughly
Helps avoid re-exposure and supports pharmacovigilance

📌 This case underscores the importance of patient-reported symptoms — even when they seem unrelated to the intended treatment.

❌ Debunking Misconceptions

❌ “Only oral or IV drugs cause Sweet syndrome”
False — systemic absorption of inhaled meds can still provoke immune reactions
❌ “It’s just a rash — treat with antibiotics”
Dangerous error — misdiagnosis leads to unnecessary antibiotics and delayed care
❌ “Sweet syndrome is contagious”
No — it’s an inflammatory condition, not infectious
❌ “All rashes after inhalers are allergies”
Not true — could be irritation, infection, or non-allergic immune reactions like this one

Final Thoughts

This case reminds us that even familiar treatments can carry unfamiliar risks.

While indacaterol/glycopyrronium remains a safe and effective option for most COPD patients, this rare event highlights the need for vigilance in primary care.

When a patient reports sudden, unexplained symptoms shortly after a medication change — especially involving skin, fever, or inflammation — consider the possibility of drug-induced syndromes, even with inhaled agents.

Because real medicine isn’t just about protocols. It’s about paying attention to patterns — and acting before small signals become big problems.

And sometimes, the most powerful tool in healthcare? It’s curiosity — paired with care.