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# Dextromethorphan
## Overview
Dextromethorphan is a cough suppressant (antitussive) that acts centrally on the cough center in the medulla. It is available in various formulations, often combined with other ingredients in over-the-counter (OTC) cold and cough products.
## Primary Indications
Symptomatic relief of cough.
## Adult Dosing
* **Immediate-release:** 10-20 mg every 4 hours, or 30 mg every 6-8 hours.
* **Extended-release:** 60 mg every 12 hours.
* **Maximum dose:** Generally 120 mg per day for immediate-release, and 120 mg per day for extended-release, but consult specific product labeling as formulations vary.
## Pediatric Dosing
* **Ages 6-11 years:**
* Immediate-release: 10 mg every 4 hours, or 15 mg every 6-8 hours.
* Maximum dose: Generally 60 mg per day.
* **Ages 4-5 years:** Dosing is highly variable and depends on the specific product formulation and concentration. **Use with caution and consult product labeling or a pediatrician.**
* **Ages < 4 years:** Generally **not recommended** due to risk of serious adverse events. Consult a pediatrician.
## Dose Adjustments
No specific dose adjustments are typically required for renal or hepatic impairment, but caution is advised, and lower doses may be considered, especially in severe impairment.
## Contraindications
* Hypersensitivity to dextromethorphan.
* Use within 14 days of MAOI therapy (risk of serotonin syndrome).
* Concomitant use with selective serotonin reuptake inhibitors (SSRIs), serotonin-norepinephrine reuptake inhibitors (SNRIs), tricyclic antidepressants (TCAs), triptans, or other drugs that affect serotonin levels requires caution due to potential for serotonin syndrome.
## Adverse Effects
Common: Dizziness, drowsiness, nausea, vomiting, constipation.
Serious: Serotonin syndrome (especially with concomitant serotonergic agents), confusion, hallucinations, respiratory depression (at high doses or in combination products).
## Key Drug Interactions
* **MAOIs:** Contraindicated.
* **SSRIs, SNRIs, TCAs, triptans, St. John's Wort:** Increased risk of serotonin syndrome.
* **CYP2D6 inhibitors (e.g., fluoxetine, paroxetine, quinidine):** May increase dextromethorphan plasma concentrations, leading to increased adverse effects.
* **Alcohol and CNS depressants:** Additive sedative effects.
## Monitoring
Monitor for effectiveness in suppressing cough and for adverse effects, particularly signs of serotonin syndrome (agitation, hallucinations, rapid heart rate, fever, sweating, muscle stiffness, tremor, loss of coordination, nausea, vomiting, diarrhea).
## Clinical Pearls
* Dextromethorphan is often part of multi-symptom cold and cough remedies; ensure no duplication of ingredients if using multiple products.
* Effectiveness in very young children (<4 years) is not well-established, and risks may outweigh benefits.
* Patient education regarding potential for abuse and diversion is important, especially for liquid formulations.
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**Disclaimer:** This information is intended for healthcare professionals and is not a substitute for professional medical advice. Always verify current prescribing information with the official product labeling and consult with a healthcare provider for specific patient care decisions.
