What is the role of methylprednisolone in treating chronic cough, particularly in patients with suspected inflammatory conditions such as asthma or eosinophilic bronchitis?

Methylprednisolone in Chronic Cough

For chronic cough due to asthma or eosinophilic bronchitis, reserve oral corticosteroids like methylprednisolone for severe or refractory cases after inhaled corticosteroids and bronchodilators have failed—use a short 1-2 week course (prednisolone 30 mg daily equivalent) followed by transition to inhaled corticosteroids. 1

When to Use Systemic Corticosteroids

Patients with severe and/or refractory cough due to asthma should receive a short course (1 to 2 weeks) of systemic (oral) corticosteroids followed by inhaled corticosteroids. 1 This represents a Grade B recommendation with substantial net benefit despite low quality evidence. 1

Specific Indications for Oral Steroids:

• Refractory asthmatic cough that persists despite adequate doses of inhaled corticosteroids and bronchodilators, after excluding poor compliance or other contributing conditions 1
• Diagnostic trial when testing is unavailable—prednisolone 30 mg daily for 2 weeks establishes whether cough is due to eosinophilic airway inflammation 1, 2
• Severe presentations requiring rapid symptom control before maintenance inhaled therapy takes effect 1

Treatment Algorithm

First-Line Approach (Do NOT Start with Oral Steroids):

• Inhaled corticosteroids are first-line treatment for both cough variant asthma and non-asthmatic eosinophilic bronchitis 1, 3
• Start with standard doses (beclomethasone 200-800 μg daily equivalent) combined with bronchodilators for asthma 1, 2
• Allow 4-8 weeks for full therapeutic response 4, 2

Escalation Steps Before Systemic Steroids:

1. Increase inhaled corticosteroid dose up to 2000 μg beclomethasone daily equivalent 2
2. Add leukotriene receptor antagonist (montelukast) before escalating to systemic corticosteroids 1, 2
3. Reassess for alternative causes of cough at each step 1

When to Use Methylprednisolone/Prednisolone:

• Only after steps 1-2 fail and severe symptoms persist 1
• Dosing: Prednisolone 30 mg daily (or methylprednisolone equivalent) for 1-2 weeks 1, 2
• Transition immediately to high-dose inhaled corticosteroids after the short oral course 1

Critical Diagnostic Considerations

Confirm Eosinophilic Inflammation:

• Non-invasive measurement of airway inflammation (sputum eosinophils, FeNO, blood eosinophils) predicts corticosteroid responsiveness 1, 4
• Patients without sputum eosinophilia do not respond to corticosteroids—do not use methylprednisolone in this population 3, 5

Distinguish Asthma from Eosinophilic Bronchitis:

• Bronchial challenge testing (methacholine) demonstrates airway hyperresponsiveness in asthma but is negative in non-asthmatic eosinophilic bronchitis 1, 4, 2
• Both conditions respond to corticosteroids, but this distinction guides long-term management 1, 6
• A negative hyperresponsiveness test excludes asthma but does not rule out steroid-responsive cough 1, 2

Common Pitfalls to Avoid

Do Not Use Oral Steroids When:

• Inhaled corticosteroids have not been tried first—this violates guideline-based stepwise therapy 1
• Sputum shows no eosinophilia—these patients have 100% treatment failure with corticosteroids 3, 5
• Alternative diagnoses have not been excluded—particularly gastroesophageal reflux disease, upper airway cough syndrome, or ACE inhibitor use 1, 2

Diagnostic Trial Interpretation:

• If no response to prednisolone 30 mg daily for 2 weeks, cough is unlikely due to eosinophilic airway inflammation—pursue alternative diagnoses 1, 2
• Corticosteroid response does not distinguish between cough variant asthma and eosinophilic bronchitis—both respond similarly 1

Evidence Quality and Nuances

The recommendation for systemic corticosteroids in refractory asthmatic cough carries Grade B strength with low quality evidence but substantial net benefit. 1 The 2020 CHEST guidelines emphasize that cough-specific studies are limited because cough is not captured independently in most asthma trials. 1

Inhaled corticosteroids show modest benefit in chronic persistent cough (mean decrease 0.34 standard deviations), but evidence quality is low due to significant heterogeneity. 7 One study showed fluticasone 500 μg twice daily for 14 days significantly improved cough visual analogue scale scores and reduced sputum eosinophilic cationic protein. 8

The presence of non-asthmatic corticosteroid-responsive cough syndromes emphasizes the importance of a corticosteroid trial in all patients with chronic cough, regardless of airway function tests. 1, 2 However, this trial should be with inhaled corticosteroids first, reserving oral agents for refractory cases. 1

Long-Term Considerations

• 30-40% of cough variant asthma patients progress to classic asthma if inadequately treated, making early and adequate corticosteroid therapy critical 4, 9
• Inhaled corticosteroids prevent airway remodeling and reduce progression risk 9
• After oral steroid course, maintain long-term control with inhaled corticosteroids—do not use repeated courses of oral steroids 1