What are the recommended treatments for a persistent cough reflex?

Management of Persistent Cough Reflex

For persistent chronic cough (>8 weeks), follow a systematic diagnostic and treatment algorithm targeting the most common causes in sequence: upper airway cough syndrome (UACS), asthma/eosinophilic bronchitis, and gastroesophageal reflux disease (GERD), with gabapentin and speech pathology therapy reserved for unexplained refractory cases. 1

Initial Mandatory Evaluation

• Obtain chest radiograph and spirometry in all patients with chronic cough to exclude structural lung disease, malignancy, and assess baseline lung function 1
• Perform bronchial provocation testing (methacholine challenge) in patients with normal spirometry and no clinically obvious cause 1
• Assess cough severity and quality of life impact using validated questionnaires or visual analogue scores 1

Critical History Elements

• Discontinue ACE inhibitors immediately if the patient is taking them—this is the only uniformly effective treatment for ACE inhibitor-induced cough, which resolves in 1-4 weeks (occasionally up to 3 months) 1
• Document smoking status—smoking is one of the most common causes and cessation should be strongly encouraged 1
• Identify symptoms suggesting upper airway involvement: throat clearing, post-nasal drip sensation, or rhinosinusitis 1
• Ask about reflux triggers: cough with talking/phonation, postprandial timing, or positional changes 1

Sequential Treatment Algorithm

First-Line: Upper Airway Cough Syndrome (UACS)

• Trial topical nasal corticosteroids for patients with prominent upper airway symptoms (rhinosinusitis, post-nasal drip) 1
• This should be the initial empiric treatment when upper airway symptoms are present 1

Second-Line: Asthma/Eosinophilic Bronchitis

• Administer a 2-week trial of oral corticosteroids (e.g., prednisone) to assess for corticosteroid-responsive cough 1
• If no response after 2 weeks, eosinophilic airway inflammation is effectively ruled out 1
• If positive response, transition to inhaled corticosteroids for maintenance 1
• Consider adding leukotriene inhibitors before escalating to oral corticosteroids in suspected asthmatic cough 1

Third-Line: Gastroesophageal Reflux Disease

• Prescribe intensive acid suppression with proton pump inhibitors (PPIs) plus alginates for minimum 3 months 1
• This extended duration is critical—GERD-related cough may take weeks to months to respond, unlike UACS or asthma 1
• Consider adding prokinetic therapy (metoclopramide) if initial PPI therapy fails 1
• Note: In patients with negative workup for GERD, do not prescribe PPIs 1

Unexplained Chronic Cough Management

When systematic evaluation and treatment of common causes fails:

Diagnostic Confirmation

• Ensure objective testing for bronchial hyperresponsiveness and eosinophilic bronchitis has been completed 1
• Do not prescribe inhaled corticosteroids if tests for bronchial hyperresponsiveness and eosinophilia (sputum eosinophils, exhaled nitric oxide) are negative 1

Treatment Options for Refractory Cases

Gabapentin (Preferred Pharmacologic Option):

• Start gabapentin 300 mg once daily, escalating as tolerated to maximum 1,800 mg daily in two divided doses 1
• Discuss potential side effects and risk-benefit profile before initiation 1
• Reassess risk-benefit at 6 months before continuing 1
• This recommendation is based on demonstrated quality of life improvement in randomized controlled trials 1

Multimodality Speech Pathology Therapy:

• Refer for speech pathology therapy as a non-pharmacologic option for unexplained chronic cough 1
• This addresses the underlying cough reflex hypersensitivity that characterizes refractory chronic cough 2, 3

Common Pitfalls to Avoid

• Never continue ACE inhibitors in a patient with troublesome cough—switch to an angiotensin receptor blocker (ARB) if indicated, which has similar cough incidence to placebo 1
• Do not assume cough is due to an underlying condition (e.g., interstitial lung disease) without first evaluating for the common triad of UACS, asthma, and GERD 4
• Avoid premature diagnosis of "unexplained" cough—ensure adequate treatment duration, especially for GERD (minimum 3 months) 1
• Do not prescribe antibiotics for acute viral cough—they are ineffective and promote resistance 2

Symptomatic Treatment Considerations

For acute cough (<3 weeks) or symptomatic relief:

• Dextromethorphan temporarily relieves cough and helps with sleep 5, 2
• Guaifenesin helps loosen mucus and thin bronchial secretions 6
• Limited evidence supports specific pharmacologic effect of over-the-counter preparations, though patients report subjective benefit 1

When to Refer

• Persistent cough despite systematic evaluation and treatment trials 1
• Red flag symptoms: hemoptysis, significant weight loss, fever with systemic illness, or suspicion of malignancy 1
• Consider high-resolution CT if targeted investigations are normal and cough persists 1