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# Dextromethorphan/Guaifenesin
## Overview
Dextromethorphan is a cough suppressant. Guaifenesin is an expectorant. This combination product is used to relieve cough and help thin mucus.
## Primary Indications
* Symptomatic relief of cough due to common cold or other upper respiratory irritations.
* Temporary relief of chest congestion.
## Adult Dosing
* **Dextromethorphan:** Typically 10-20 mg every 4 hours, or 30 mg every 6-8 hours. Maximum dose: 120 mg per 24 hours.
* **Guaifenesin:** Typically 200-400 mg every 4 hours. Maximum dose: 2400 mg per 24 hours.
*Note: Specific dosing varies by product formulation. Always refer to the product label for the exact strengths of each component and the recommended dosage for that specific product.*
## Pediatric Dosing
* **Dextromethorphan:**
* 6 to under 12 years: 5-10 mg every 4 hours, or 15 mg every 6-8 hours. Maximum dose: 60 mg per 24 hours.
* Under 6 years: Use is generally not recommended without consulting a healthcare provider.
* **Guaifenesin:**
* 6 to under 12 years: 100-200 mg every 4 hours. Maximum dose: 1200 mg per 24 hours.
* Under 6 years: Use is generally not recommended without consulting a healthcare provider.
*Note: Always refer to the product label for pediatric dosing instructions. These are general guidelines and may differ based on specific product formulation and age/weight criteria.*
## Dose Adjustments
No dose adjustments are typically required for renal or hepatic impairment, but caution may be advised in severe cases.
## Contraindications
* Hypersensitivity to dextromethorphan or guaifenesin.
* Use within 14 days of MAOI therapy (for dextromethorphan).
* Use in patients with narrow-angle glaucoma or urinary retention (due to potential anticholinergic effects of some combination products, though less common with dextromethorphan alone).
* Children under 2 years of age (specific warnings and contraindications may apply to certain formulations).
## Adverse Effects
* **Dextromethorphan:** Dizziness, drowsiness, nausea, vomiting, confusion, and in rare cases, serotonin syndrome if combined with other serotonergic agents.
* **Guaifenesin:** Nausea, vomiting, stomach pain, dizziness, headache, rash.
## Key Drug Interactions
* **Dextromethorphan:**
* MAOIs: Risk of hypertensive crisis or serotonin syndrome.
* SSRIs, SNRIs, tricyclic antidepressants, other serotonergic drugs: Increased risk of serotonin syndrome.
* CYP2D6 inhibitors (e.g., fluoxetine, paroxetine, quinidine): May increase dextromethorphan plasma concentrations, leading to increased adverse effects.
* Alcohol: Additive CNS depression.
* **Guaifenesin:** Generally has few significant drug interactions.
## Monitoring
* Monitor for signs of therapeutic effect (cough suppression, thinning of mucus).
* Monitor for adverse effects, particularly CNS effects with dextromethorphan and GI upset with guaifenesin.
* Monitor for signs of serotonin syndrome if co-administered with other serotonergic agents.
## Clinical Pearls
* This combination product is for symptomatic relief only. The underlying cause of the cough should be addressed.
* Adequate hydration is crucial for guaifenesin to be effective in thinning mucus.
* Dextromethorphan can be abused for its euphoric effects at high doses.
* Be aware of other ingredients in combination cold products (e.g., decongestants, antihistamines, analgesics) and potential interactions or contraindications.
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*Disclaimer: This information is intended for healthcare professionals. Always consult the most current prescribing information and relevant literature before making clinical decisions. Drug information can change.*
