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RESPIRATORY SYSTEM › COUGH AND COLD PREPARATIONS › EXPECTORANTS, EXCL. COMBINATIONS WITH COUGH SUPPRESSANTS › Expectorants
combinations
R05CA10
Forms & Strengths
- Syrup 10 mg/5 mL dextromethorphan + 100 mg/5 mL guaifenesin
- Extended‑release tablets 30 mg dextromethorphan + 200 mg guaifenesin
- Oral solution 2 mg/5 mL dextromethorphan + 20 mg/5 mL guaifenesin
Adult Dosing
- Cough suppressant: 10‑20 mg dextromethorphan PO q6‑8h (max 120 mg/24h)
- Expectorant: 200‑400 mg guaifenesin PO q4‑6h (max 2400 mg/24h)
- Combination product: 10 mg/100 mg dextromethorphan/guaifenesin PO q6h
Pediatric Dosing
- Infants < 2 yr: not recommended unless prescribed by physician
- Children 2‑6 yr: 2‑4 mg dextromethorphan + 20‑40 mg guaifenesin PO q8h
- Children 6‑12 yr: 5‑10 mg dextromethorphan + 100‑200 mg guaifenesin PO q6h
Indications
- Temporary relief of non‑productive cough associated with common cold or upper respiratory infection
- Facilitation of productive cough by thinning bronchial secretions
Mechanism of Action
- Dextromethorphan: sigma‑1 receptor agonist with NMDA antagonism; suppresses cough center in medulla
- Guaifenesin: increases hydration of airway secretions, reduces viscosity, and promotes mucociliary clearance
Contraindications
- Hypersensitivity to dextromethorphan, guaifenesin, or excipients
- Use of MAO‑inhibitors within 14 days (dextromethorphan)
- Severe respiratory depression
Adverse Reactions
- Dextromethorphan: dizziness, nausea, dysphoria, rare serotonin syndrome
- Guaifenesin: gastrointestinal upset, rash, headache
Drug Interactions
- MAO inhibitors – risk of hypertensive crisis and serotonin syndrome with dextromethorphan
- Selective serotonin reuptake inhibitors – additive serotonergic effect
- CYP2D6 inhibitors (e.g., fluoxetine, quinidine) – increase dextromethorphan levels
Curated Content: Needs Vetting Before Put to Clinical Use