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# Dextromethorphan (DM) Cold
## Overview
Dextromethorphan is an antitussive (cough suppressant) that acts centrally on the cough center in the medulla oblongata. It is commonly found in over-the-counter (OTC) combination products for cold and cough symptoms.
## Primary Indications
* Symptomatic relief of cough due to common cold, allergies, or minor throat irritation.
## Adult Dosing
* **Oral:** 10 mg to 20 mg every 4 hours as needed, OR 30 mg every 6 to 8 hours as needed.
* **Maximum:** Typically 120 mg in 24 hours, but may vary by product formulation. Always check specific product labeling.
## Pediatric Dosing
* **Ages 6 to 12 years:** 5 mg to 10 mg every 4 hours as needed, OR 15 mg every 6 to 8 hours as needed.
* **Maximum:** Typically 60 mg in 24 hours, but may vary by product formulation.
* **Ages under 6 years:** Not recommended for use unless specifically directed by a healthcare provider. Combination products containing dextromethorphan are generally not recommended for children under 6 years of age due to potential for serious adverse effects and lack of proven efficacy.
## Dose Adjustments
* No specific dose adjustments are typically required for renal or hepatic impairment, but caution and lower doses may be warranted in severe hepatic dysfunction. Always consult product labeling and consider patient-specific factors.
## Contraindications
* Hypersensitivity to dextromethorphan.
* Use within 14 days of MAO inhibitor therapy.
* Use in patients with narrow-angle glaucoma, urinary retention, or pyloric stenosis (caution due to potential anticholinergic effects in some combination products).
* Use in patients with respiratory depression or chronic bronchitis/emphysema where cough suppression may be detrimental.
## Adverse Effects
* **Common:** Dizziness, drowsiness, nausea, vomiting.
* **Less Common:** Confusion, nervousness, constipation, rash.
* **Rare/Serious:** Respiratory depression, serotonin syndrome (especially with concomitant serotonergic agents), abuse potential.
## Key Drug Interactions
* **Monoamine Oxidase Inhibitors (MAOIs):** Concomitant use can lead to serious, potentially fatal reactions including hypertension, hyperpyrexia, seizures, and coma. Avoid use within 14 days of MAOI therapy.
* **Serotonergic Agents (e.g., SSRIs, SNRIs, tricyclic antidepressants, triptans, fentanyl):** Increased risk of serotonin syndrome.
* **Alcohol and CNS Depressants:** Additive CNS depression.
* **CYP2D6 Inhibitors (e.g., fluoxetine, paroxetine, quinidine):** May increase dextromethorphan plasma concentrations, increasing the risk of adverse effects.
## Monitoring
* Monitor for effectiveness of cough suppression.
* Monitor for signs and symptoms of adverse effects, particularly CNS effects and serotonin syndrome.
## Clinical Pearls
* Dextromethorphan is available in various formulations (syrups, tablets, capsules). Ensure the patient is using the correct dosage form and strength.
* Many OTC cold and cough products contain multiple ingredients. Advise patients to read labels carefully to avoid duplication of ingredients and potential overdose.
* Dextromethorphan is a frequently abused substance. Counsel patients on appropriate use and potential for misuse.
* Dextromethorphan itself does not have analgesic properties.
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*Disclaimer: This information is intended for healthcare professionals and should not be considered a substitute for professional medical advice. Always consult the most current prescribing information and product labeling before making any treatment decisions. Drug formulations, indications, and dosing recommendations can vary. Local protocols may also influence drug use.*
