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# Dextromethorphan/Guaifenesin (D%25252525252525252525252525252525252525252520cold) ## Overview Dextromethorphan is a cough suppressant, and guaifenesin is an expectorant. Combination products are available. ## Primary Indications Symptomatic relief of cough and chest congestion associated with the common cold or other respiratory conditions. ## Adult Dosing * **Dextromethorphan:** Typically 10-20 mg every 4 hours, or 30 mg every 6-8 hours. Maximum 120 mg per 24 hours. * **Guaifenesin:** Typically 200-400 mg every 4 hours. Maximum 2400 mg per 24 hours. * Specific dosing for combination products will vary and should be confirmed with the product labeling. ## Pediatric Dosing Dosing for combination products in pediatric patients is highly variable and depends on the specific product and age/weight. Dextromethorphan and guaifenesin are **not recommended for children under 6 years of age** unless specifically directed by a healthcare provider due to the risk of serious adverse effects. * **Dextromethorphan:** * 6-12 years: 5-10 mg every 4 hours, or 15 mg every 6-8 hours. Maximum 60 mg per 24 hours. * Under 6 years: Use with caution and only under provider direction. * **Guaifenesin:** * 6-12 years: 100-200 mg every 4 hours. Maximum 1200 mg per 24 hours. * Under 6 years: Use with caution and only under provider direction. ## Dose Adjustments No specific dose adjustments are typically required for renal or hepatic impairment, but caution is advised and lower doses may be considered. ## Contraindications * Hypersensitivity to components. * Use within 14 days of MAOI therapy (dextromethorphan). * Children under 6 years of age for over-the-counter use. ## Adverse Effects * **Dextromethorphan:** Dizziness, drowsiness, nausea, vomiting, constipation. High doses can cause confusion, hallucinations, respiratory depression, and serotonin syndrome. * **Guaifenesin:** Nausea, vomiting, stomach pain. ## Key Drug Interactions * **MAOIs and other serotonergic agents:** Increased risk of serotonin syndrome with dextromethorphan. * **CNS depressants (e.g., alcohol, sedatives, benzodiazepines):** Additive sedative effects. * **CYP2D6 inhibitors (e.g., fluoxetine, paroxetine, quinidine):** Can increase dextromethorphan plasma concentrations, increasing the risk of toxicity. ## Monitoring * Effectiveness of cough suppression and expectoration. * Signs of adverse effects, particularly CNS effects with dextromethorphan. * Signs of serotonin syndrome if co-administered with other serotonergic agents. ## Clinical Pearls * Combination products vary widely in their exact drug concentrations. Always verify the specific formulation being used. * Dextromethorphan can be misused for its psychoactive effects at high doses. * Guaifenesin is intended to help loosen mucus, making coughs more productive. Adequate hydration is important for its effectiveness. * Dextromethorphan is a substrate of CYP2D6, leading to significant inter-individual variability in metabolism. *** *This information is for educational purposes only and does not substitute for professional medical advice. Always consult with a qualified healthcare provider to determine the appropriateness of any medication or treatment for your specific condition. Verify current prescribing information and product monographs for complete details.*