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# Dextromethorphan/Guaifenesin
## Overview
Dextromethorphan is a cough suppressant. Guaifenesin is an expectorant that helps thin mucus. This combination product is used to relieve cough and loosen mucus associated with the common cold.
## Primary Indications
* Symptomatic relief of cough
* Loosening of mucus in the airways
## Adult Dosing
* **Dextromethorphan:** 10 mg to 20 mg every 4 hours, OR 30 mg every 6 to 8 hours.
* **Guaifenesin:** 200 mg to 400 mg every 4 hours, OR 600 mg to 1200 mg every 12 hours.
* **Combination Products:** Dosing varies by specific product formulation. Always consult the product labeling for the exact strengths of dextromethorphan and guaifenesin and follow the recommended dosing schedule. Maximum daily doses should not be exceeded.
## Pediatric Dosing
Dosing is highly dependent on the specific product formulation and the child's age and weight. Consult product labeling or a pediatrician. Generally:
* **Children 6-11 years:** Dextromethorphan 5-10 mg every 4 hours, or 15 mg every 6-8 hours. Guaifenesin 100-200 mg every 4 hours, or 400 mg every 12 hours.
* **Children under 6 years:** Use is generally not recommended for combination products unless specifically directed by a healthcare provider. Dosing for younger children should be individualized and based on weight.
## Dose Adjustments
No specific dose adjustments are typically required for hepatic or renal impairment, but caution may be advised, especially in severe impairment. Consult product labeling or a healthcare provider.
## Contraindications
* Hypersensitivity to dextromethorphan or guaifenesin.
* Use within 14 days of MAOI therapy (for dextromethorphan component).
* Children under 6 years of age for certain formulations (consult product labeling).
## Adverse Effects
* **Dextromethorphan:** Dizziness, drowsiness, confusion, nausea, vomiting, constipation. Serotonin syndrome can occur with overdose or concomitant use of serotonergic agents.
* **Guaifenesin:** Nausea, vomiting, dizziness, headache, rash.
## Key Drug Interactions
* **Monoamine Oxidase Inhibitors (MAOIs):** Dextromethorphan can cause severe serotonin syndrome when used with MAOIs. Avoid concurrent use and for 14 days after discontinuing MAOIs.
* **Serotonergic Agents:** Increased risk of serotonin syndrome when used with SSRIs, SNRIs, tricyclic antidepressants, triptans, and other serotonergic drugs.
* **CNS Depressants:** Increased risk of sedation and CNS depression with alcohol, benzodiazepines, opioids, and sedating antihistamines.
* **CYP2D6 Inhibitors:** May increase dextromethorphan levels, leading to increased adverse effects.
## Monitoring
* Monitor for effectiveness of cough suppression and mucus expectoration.
* Monitor for signs and symptoms of adverse effects, particularly CNS effects and serotonin syndrome.
## Clinical Pearls
* Combination products can lead to unintended overdosing if patients use multiple products containing the same active ingredients.
* Guaifenesin is most effective when patients remain well-hydrated.
* Dextromethorphan can be abused for its dissociative effects at higher doses.
This information is intended for healthcare professionals. Always consult the current prescribing information and relevant literature before making clinical decisions.
