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# Dextromethorphan/Guaifenesin
## Overview
Dextromethorphan is a cough suppressant. Guaifenesin is an expectorant that helps loosen mucus in the airways. This combination is intended for symptomatic relief of cough and chest congestion associated with the common cold or other respiratory infections.
## Primary Indications
* Cough suppression
* Expectorant for mucus relief
## Adult Dosing
Dosing varies widely by product formulation. Always check the specific product labeling.
* **Dextromethorphan:** Typical dosage range is 10-20 mg every 4 hours, or 30 mg every 6-8 hours. Maximum daily dose is generally 120 mg.
* **Guaifenesin:** Typical dosage range is 200-400 mg every 4 hours. Maximum daily dose is generally 2400 mg.
## Pediatric Dosing
Dosing for children depends on age and the specific product formulation. **Always consult the product labeling for age-appropriate dosing.**
* **Dextromethorphan:**
* Children 6-12 years: 5-10 mg every 4 hours, or 15 mg every 6-8 hours. Maximum daily dose is generally 60 mg.
* Children under 6 years: Use is generally **not recommended** unless specifically directed by a healthcare provider. Some products may be available for children 2-5 years.
* **Guaifenesin:**
* Children 6-12 years: 100-200 mg every 4 hours. Maximum daily dose is generally 1200 mg.
* Children under 6 years: Use is generally **not recommended** unless specifically directed by a healthcare provider. Some products may be available for children 2-5 years.
## Dose Adjustments
* **Renal Impairment:** No specific dose adjustments are typically required for mild to moderate renal impairment. Use with caution in severe renal impairment.
* **Hepatic Impairment:** Use with caution. Dextromethorphan is metabolized by the liver.
## Contraindications
* Hypersensitivity to dextromethorphan or guaifenesin.
* Use within 14 days of MAOI therapy (for dextromethorphan).
* Cough associated with asthma or persistent bronchitis (may mask symptoms).
* Children under 2 years (specific product limitations may apply).
## Adverse Effects
* **Dextromethorphan:** Drowsiness, dizziness, nausea, vomiting, constipation, confusion, respiratory depression (at high doses). Serotonin syndrome is a risk, especially with other serotonergic agents.
* **Guaifenesin:** Nausea, vomiting, dizziness, headache, rash.
## Key Drug Interactions
* **MAOIs, SSRIs, SNRIs, triptans, linezolid, St. John's wort:** Increased risk of serotonin syndrome with dextromethorphan.
* **CNS depressants (alcohol, benzodiazepines, opioids):** Additive sedative effects.
* **CYP2D6 inhibitors (e.g., fluoxetine, paroxetine, quinidine):** May increase dextromethorphan levels and risk of toxicity.
## Monitoring
* Monitor for effectiveness of cough and mucus relief.
* Assess for adverse effects, particularly sedation, confusion, and signs of serotonin syndrome.
## Clinical Pearls
* This combination product is for symptomatic relief only. Treat the underlying cause of the cough.
* Ensure adequate hydration, which can help guaifenesin's expectorant effect.
* Be aware of the potential for abuse of dextromethorphan at higher than recommended doses.
* Many over-the-counter products contain these ingredients; carefully review all medications being taken to avoid duplication.
***
**Disclaimer:** This information is intended for healthcare professionals and is not a substitute for professional medical advice. Always verify the most current prescribing information and consult with a qualified healthcare provider before making any treatment decisions. Pediatric dosing often requires specific product selection and strict adherence to age and weight-based recommendations.
