In an adult asthma patient already on optimized inhaled corticosteroid (ICS) and long‑acting β2‑agonist (LABA) therapy who still has a persistent cough, can isotonic (0.9%) saline nebulisation be used as a symptom‑relieving adjunct?

Isotonic Saline Nebulization for Persistent Cough in Optimized Asthma

Isotonic (0.9%) saline nebulization is not recommended as a symptom-relieving adjunct for persistent cough in asthma patients already on optimized ICS/LABA therapy, as there is no guideline or evidence support for this intervention in asthma-related cough management. 1

Why Saline Nebulization Is Not Indicated

• The CHEST guideline on managing chronic cough due to asthma provides no recommendation for saline nebulization as an adjunctive therapy for asthma-related cough 1
• The British Thoracic Society nebulizer guidelines restrict nebulized therapy in chronic asthma to bronchodilators (beta-agonists and ipratropium) only, with no mention of saline for symptom relief 1
• Nebulized bronchodilators in chronic asthma should only be used at Step 4 or above when patients have persistent daily wheeze despite optimized therapy, not for isolated cough 1

What Should Be Done Instead: Algorithmic Approach

Step 1: Reassess the Diagnosis

• Confirm that cough is truly asthma-related by measuring airway inflammation using sputum eosinophils, blood eosinophils, or fractional exhaled nitric oxide (FeNO), as eosinophilic airway inflammation predicts favorable response to corticosteroids 1
• Consider alternative diagnoses including non-asthmatic eosinophilic bronchitis (NAEB), which presents as isolated chronic cough without airflow limitation or airway hyperresponsiveness but responds to ICS 1
• Reconsider other causes of chronic cough (gastroesophageal reflux, upper airway cough syndrome, chronic rhinosinusitis) before escalating asthma therapy 1

Step 2: Optimize Current ICS/LABA Therapy

• Verify proper inhaler technique, as poor technique is the most common cause of apparent treatment failure 2
• Confirm medication adherence before considering dose escalation 2
• Assess environmental triggers and allergen exposure that may perpetuate symptoms 3

Step 3: Escalate Asthma-Specific Therapy

• Increase the ICS dose within the ICS/LABA combination if currently on low-to-medium dose 1
• Add a leukotriene receptor antagonist (montelukast 10 mg once daily for adults) as the next step after reconsidering alternative causes 1
• The CHEST guideline specifically recommends stepping up ICS dose and adding leukotriene inhibitors for incomplete response in asthma-related cough 1

Step 4: Consider Cough Variant Asthma (CVA)

• If cough remains the isolated symptom despite optimized ICS/LABA therapy, this may represent CVA, which requires the same stepwise escalation approach 1
• Beta-agonists combined with ICS are appropriate for CVA, which the patient already has via ICS/LABA therapy 1

Critical Pitfall to Avoid

• Never use nebulized bronchodilators (salbutamol or terbutaline) as chronic daily therapy for cough alone 1
• Nebulized beta-agonists in chronic asthma are reserved for persistent daily wheeze at Step 4 or above, and require demonstration of clinically useful bronchodilation (≥15% improvement in peak flow) during a 2-week home trial before long-term prescription 1
• Frequent use of rescue bronchodilators (>2 days/week) indicates inadequate asthma control and necessitates controller therapy escalation, not nebulized saline 4, 2

Evidence Strength

The absence of any mention of saline nebulization across multiple high-quality asthma and cough management guidelines (CHEST 2020, British Thoracic Society, GINA-derived recommendations) strongly indicates this is not an evidence-based intervention for asthma-related cough 1, 4, 2, 3.