Is diphenhydramine (antihistamine) effective for treating chesty cough or dry cough?

Diphenhydramine is Not Recommended for Chesty or Dry Cough

Diphenhydramine is not recommended for treating either chesty or dry cough as it has minimal to no efficacy in relieving cough symptoms and may be associated with adverse events. 1

Evidence Against Diphenhydramine for Cough

• Clinical guidelines consistently show that antihistamines, including diphenhydramine, have minimal to no efficacy in relieving cough in children or adults 1
• A randomized controlled trial demonstrated that diphenhydramine was no different than placebo in reducing nocturnal cough or sleep disturbance in both children and parents 1
• Over-the-counter (OTC) cough medications containing antihistamines like diphenhydramine have been associated with adverse events, including potential serious side effects in children 1, 2
• Honey has been shown to offer more relief for cough symptoms than diphenhydramine or placebo in children with acute cough 1, 3

Safety Concerns

• Diphenhydramine exposures in children may result in adverse events including tachycardia (53.4%), hallucinations (46.5%), somnolence (34.7%), agitation (33.9%), and mydriasis (26.3%) 2
• The FDA has issued warnings against using OTC cough medications in young children, and manufacturers have voluntarily relabeled these products "do not use in children under 4 years of age" 1
• The American Academy of Pediatrics advises against using diphenhydramine for treating any type of cough due to potential side effects and limited efficacy 1

Recommended Alternatives for Cough Management

For Dry Cough:

• In adults with chronic bronchitis, central cough suppressants such as codeine and dextromethorphan may be recommended for short-term symptomatic relief 1
• For cough due to upper respiratory infections, neither central nor peripheral cough suppressants are recommended due to limited efficacy 1
• In children over 1 year of age with acute dry cough, honey is recommended as first-line therapy, providing more relief than diphenhydramine or placebo 3

For Chesty (Productive) Cough:

• In patients with bronchitis, hypertonic saline solution and erdosteine are recommended on a short-term basis to increase cough clearance 1
• For patients with chronic bronchitis, peripheral cough suppressants such as levodropropizine and moguisteine may be recommended for short-term symptomatic relief 1
• In patients with cough due to asthma or COPD, ipratropium bromide is the only inhaled anticholinergic agent recommended for cough suppression 1, 4

Appropriate Diagnostic Approach

• Determine if the cough is acute (<4 weeks) or chronic (>4 weeks) to guide management approach 3
• Identify if the cough is specific (with pointers to underlying disease) or non-specific (dry cough without specific indicators) 3
• For chronic cough, evaluate for "cough pointers" that suggest specific etiologies requiring targeted treatment, such as wheezing (suggests asthma), digital clubbing, coughing with feeding, or abnormal chest radiograph or spirometry 3
• The British Thoracic Society recommends spirometry in all patients with chronic cough to identify reversible airflow obstruction that might respond to appropriate treatment 4

Common Pitfalls to Avoid

• Using diphenhydramine for cough based on its sedative properties rather than actual antitussive efficacy 1
• Continuing to use OTC cough medications despite evidence showing little to no benefit in symptomatic control of cough 1, 5
• Failing to address the underlying cause of chronic cough and instead focusing only on symptomatic treatment 1, 3
• Using adult cough management approaches in pediatric patients, where evidence and recommendations differ significantly 3

Despite one older study suggesting diphenhydramine may have antitussive effects in an experimental citric acid aerosol-induced cough model 6, more recent and comprehensive clinical guidelines consistently recommend against its use for cough due to limited efficacy and potential adverse effects 1, 3.