Management of Allergic Cough
For allergic cough, begin treatment with a first-generation antihistamine/decongestant combination as the primary intervention, addressing the underlying upper airway inflammation that drives the cough reflex. 1
Confirm the Allergic Etiology
- Verify the diagnosis through allergy skin testing to differentiate allergic from non-allergic causes, as postnasal drip from allergic rhinitis is the single most common cause of chronic cough 1
- Document specific allergen triggers (pollen, dust mites, pet dander) and their temporal relationship to cough symptoms 1
- Rule out ACE inhibitor use, as this is a common drug-induced cause that mimics allergic cough 1, 2
- Assess smoking status and counsel for cessation, as tobacco exposure exacerbates any allergic respiratory condition 1
Initial Pharmacologic Management
Start with a first-generation antihistamine/decongestant combination as this directly treats upper airway cough syndrome (UACS) from allergic rhinitis 1, 2, 3. This is more effective than newer non-sedating antihistamines for cough suppression due to anticholinergic properties.
If Cough Persists After 1-2 Weeks
- Add intranasal corticosteroids (fluticasone propionate 200 mcg daily or mometasone furoate 200 mcg daily) to reduce nasal inflammation 4, 5
- Fluticasone can be dosed as two 50-mcg sprays in each nostril once daily, with symptom improvement beginning within 12 hours and maximum effect in several days 4
- Mometasone has demonstrated significant improvement in daytime cough severity scores compared to placebo in patients with seasonal allergic rhinitis (P = 0.049) 5
Consider Alternative Antihistamine Therapy
- Loratadine 10 mg daily may be beneficial if sedation from first-generation antihistamines is problematic, as it has shown efficacy in reducing both cough frequency (P < 0.05) and intensity (P < 0.01) in allergic rhinoconjunctivitis 6
Evaluate for Coexisting Asthma
Perform spirometry to assess for reversible airflow obstruction, as 50-90% of chronic coughers may have hyperreactive airways 1, 7. Allergic cough and asthma frequently coexist.
- If spirometry shows obstruction or if testing is unavailable, initiate an empiric trial of inhaled bronchodilators and inhaled corticosteroids 1, 8
- Cough alone is a poor marker of asthma, so objective testing is critical to avoid overdiagnosis 1
Sequential and Additive Treatment Approach
Therapy must be given in sequential and additive steps because multiple causes often coexist 1. If cough persists despite treating allergic rhinitis:
- Add empiric treatment for gastroesophageal reflux disease (GERD) with proton pump inhibitors 1
- Consider non-asthmatic eosinophilic bronchitis (NAEB) and trial inhaled corticosteroids if induced sputum shows eosinophilia 8
- Systematically address all common causes: UACS, asthma, NAEB, and GERD 1
Allergen Avoidance and Immunotherapy
- Implement specific allergen avoidance measures based on skin testing results, particularly for dust mite allergy which can be highly relevant 1
- Consider allergen immunotherapy for patients with symptoms interfering with quality of life or those who have found medications ineffective, as it provides lasting benefits even after discontinuation 1
When to Escalate Evaluation
Obtain chest CT scan and bronchoscopic evaluation if cough persists after systematic treatment of common causes and uncommon etiologies need exclusion 1, 2. Do not diagnose idiopathic cough until this thorough evaluation is complete.
Common Pitfalls
- Do not rely on cough characteristics (timing, sound, productivity) for diagnosis, as these have limited diagnostic value 1, 2
- Do not use antibiotics for allergic cough unless bacterial superinfection is clearly documented 2
- Do not stop treatment prematurely—allergic inflammation requires sustained therapy, and intranasal corticosteroids need several days for maximum effect 4
- Do not treat in isolation—always assess for multiple contributing factors, as more than one cause is frequently present 1