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# Dextromethorphan / Guaifenesin (often found in combination products labeled as "D-Cold" or similar)
## Overview
This combination product contains dextromethorphan, a cough suppressant, and guaifenesin, an expectorant.
## Primary Indications
* Symptomatic relief of cough.
* Aids in loosening mucus (guaifenesin).
## Adult Dosing
Dosing varies significantly by product formulation. Always refer to the specific product label. Common dosing for extended-release formulations may be 600 mg guaifenesin / 30 mg dextromethorphan every 12 hours. Immediate-release formulations often involve higher frequency dosing with lower individual doses. Maximum dextromethorphan dose is typically 120 mg per 24 hours.
## Pediatric Dosing
Dosing varies significantly by product formulation and age.
* **Under 2 years:** Generally not recommended. Consult a pediatrician.
* **2 to under 6 years:** Refer to specific product labeling, often requiring a physician's guidance. Dosing is typically weight-based or age-based and formulation dependent.
* **6 to under 12 years:** Refer to specific product labeling. Dosing is typically weight-based or age-based and formulation dependent.
* **12 years and older:** Adult dosing may apply, but always refer to the specific product label.
## Dose Adjustments
No specific dose adjustments are routinely recommended for hepatic or renal impairment for typical over-the-counter (OTC) use, but caution is advised in severe impairment.
## Contraindications
* Hypersensitivity to dextromethorphan or guaifenesin.
* Use within 14 days of MAO inhibitor therapy.
* Patients with phenylketonuria (if aspartame is present in the formulation).
* Severe hepatic impairment.
## Adverse Effects
Common: Drowsiness, dizziness, nausea, vomiting, stomach upset.
Less Common: Confusion, nervousness, restlessness, rash, respiratory depression (at high doses).
## Key Drug Interactions
* **MAO Inhibitors:** Risk of serotonin syndrome (potentially fatal). Avoid concomitant use.
* **SSRIs/SNRIs:** Increased risk of serotonin syndrome. Use with caution.
* **CNS Depressants (e.g., alcohol, benzodiazepines, opioids):** Additive CNS depression.
* **CYP2D6 Inhibitors (e.g., fluoxetine, paroxetine, quinidine):** May increase dextromethorphan levels.
## Monitoring
* Effectiveness of cough suppression and mucus expectoration.
* Signs of adverse effects, particularly CNS depression or serotonin syndrome.
## Clinical Pearls
* Always check the specific product formulation for exact ingredients and dosing. Many combination products exist.
* Guaifenesin is most effective when the patient is well-hydrated.
* Dextromethorphan can be abused at higher doses for its dissociative effects.
* Avoid concurrent use of other medications containing dextromethorphan or guaifenesin to prevent exceeding maximum daily doses.
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*Disclaimer: This information is intended for clinical use and is not a substitute for professional medical advice. Always verify current prescribing information and consult with a healthcare provider before making any treatment decisions.*
