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# Dextromethorphan; Guaifenesin
## Overview
This combination product contains a cough suppressant (dextromethorphan) and an expectorant (guaifenesin) used for the temporary relief of cough and chest congestion.
## Primary Indications
* Cough associated with the common cold.
* Chest congestion.
## Adult Dosing
* **Dextromethorphan 10 mg / Guaifenesin 100 mg:** 10 mL to 20 mL every 4 hours as needed. Maximum 6 doses in 24 hours.
* **Dextromethorphan 20 mg / Guaifenesin 200 mg:** 10 mL every 4 hours as needed. Maximum 6 doses in 24 hours.
* **Dextromethorphan 30 mg / Guaifenesin 600 mg (extended-release):** 1 capsule every 12 hours. Maximum 2 capsules in 24 hours.
* **Dextromethorphan 60 mg / Guaifenesin 1200 mg (extended-release):** 1 capsule every 12 hours. Maximum 2 capsules in 24 hours.
*Specific dosing may vary by formulation and manufacturer; always refer to product labeling.*
## Pediatric Dosing
* **Dextromethorphan 10 mg / Guaifenesin 100 mg:**
* Children 6 to under 12 years: 5 mL to 10 mL every 4 hours as needed. Maximum 6 doses in 24 hours.
* Children 2 to under 6 years: 2.5 mL to 5 mL every 4 hours as needed. Maximum 6 doses in 24 hours.
* Children under 2 years: Safety and efficacy not established. Consult prescriber.
* **Dextromethorphan 20 mg / Guaifenesin 200 mg:**
* Children 6 to under 12 years: 5 mL every 4 hours as needed. Maximum 6 doses in 24 hours.
* Children under 6 years: Safety and efficacy not established. Consult prescriber.
* Extended-release formulations are generally not recommended for children under 12 years of age unless specifically directed by a healthcare provider.
## Dose Adjustments
No specific dose adjustments are typically required for renal or hepatic impairment, but caution is advised, especially with higher doses or prolonged use.
## Contraindications
* Hypersensitivity to dextromethorphan or guaifenesin.
* Use within 14 days of starting or stopping a monoamine oxidase inhibitor (MAOI).
* Use in patients with severe hepatic impairment.
* Use in children under 2 years of age for the liquid formulations.
## Adverse Effects
* **Dextromethorphan:** Dizziness, drowsiness, confusion, nausea, vomiting, constipation, potential for serotonin syndrome (especially with other serotonergic agents).
* **Guaifenesin:** Nausea, vomiting, dizziness, headache, rash.
## Key Drug Interactions
* **Monoamine Oxidase Inhibitors (MAOIs):** Risk of severe hypertension and serotonin syndrome.
* **Serotonergic Agents (e.g., SSRIs, SNRIs, triptans):** Increased risk of serotonin syndrome.
* **CYP2D6 Inhibitors (e.g., fluoxetine, paroxetine, quinidine):** May increase dextromethorphan plasma concentrations, increasing the risk of toxicity.
* **Central Nervous System (CNS) Depressants (e.g., alcohol, benzodiazepines, opioids):** Additive CNS depression.
## Monitoring
* Monitor for signs and symptoms of serotonin syndrome (e.g., agitation, hallucinations, rapid heart rate, fever, muscle stiffness, incoordination).
* Assess cough and congestion relief.
* Monitor for adverse effects such as drowsiness or dizziness.
## Clinical Pearls
* Encourage fluid intake to aid guaifenesin's expectorant effect.
* Avoid concurrent use of alcohol or other CNS depressants.
* Dextromethorphan can be abused at high doses for its psychoactive effects.
* This product is intended for symptomatic relief and does not treat the underlying cause of the cough or congestion.
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**Disclaimer:** This information is intended for clinical use and does not replace professional medical judgment. Always verify current prescribing information with the official product labeling or a trusted drug information resource before making clinical decisions.
