What over‑the‑counter expectorant is recommended for a patient with a productive cough, and what are the appropriate adult and pediatric dosing guidelines?

OTC Drug for Productive Cough

For productive cough with phlegm, guaifenesin is the recommended over-the-counter expectorant, though evidence for its effectiveness is limited and conflicting. 1, 2

Adult Dosing

• Guaifenesin: 10-20 mL (200-400 mg) every 4 hours, maximum 6 doses per 24 hours 3
• The dosing range allows flexible titration to increase plasma concentrations as needed 2
• Multiple daily doses are required to maintain 24-hour therapeutic effect with immediate-release formulations 2
• Extended-release formulations are available for 12-hourly dosing convenience 2

Pediatric Dosing

• Children 6 to under 12 years: 5-10 mL (100-200 mg) every 4 hours 3
• Children 2 to under 6 years: 2.5-5 mL (50-100 mg) every 4 hours 3
• Children under 2 years: Consult a physician 3
• Maximum 6 doses in 24 hours for all pediatric age groups 3

Evidence Quality and Clinical Considerations

Limited Efficacy Data

• The ACCP guidelines state that mucokinetic agents (including expectorants) show no consistent favorable effect on cough in acute bronchitis and are not recommended (Grade I recommendation) 1
• In adults with acute cough, one larger study found 75% of guaifenesin users reported the medicine was helpful versus 31% in placebo (p<0.01), but a second study showed no statistically significant differences 4
• Guaifenesin has demonstrated clinical utility primarily in chronic respiratory conditions where mucus hypersecretion is more stable, rather than acute infections 2

Mechanism of Action

• Guaifenesin acts by loosening mucus in the airways and making coughs more productive 2
• It remains the only legally marketed expectorant in the US per OTC Monograph 2

Safety Profile

• Guaifenesin has a well-established and favorable safety profile in both adult and pediatric populations 2
• It is considered safe and effective for mucus-related symptoms in stable chronic bronchitis and acute upper respiratory tract infections 2

Important Clinical Pitfalls

• Green or yellow sputum suggests bacterial infection requiring medical evaluation 5
• Persistent cough beyond 3 weeks requires full diagnostic workup rather than continued symptomatic treatment 6
• For children, over-the-counter cough medicines lack strong efficacy evidence and can delay diagnosis of more serious underlying conditions 7
• Ensure patients are not taking multiple products simultaneously to avoid unintentional overdosing on combination ingredients 5

Alternative Approach

• Simple home remedies like honey and lemon may be equally effective as first-line treatment for benign viral cough 8, 9
• For productive cough where clearance is beneficial, do not use cough suppressants as they may impair necessary mucus clearance 8