Please check your internet connection and try again.
# Dextromethorphan/Guaifenesin (Commonly found in "DayQuil Cold & Flu" or similar combination products)
## Overview
This combination product typically contains dextromethorphan, a cough suppressant, and guaifenesin, an expectorant. The exact formulation and available strengths can vary significantly between different over-the-counter brands.
## Primary Indications
* Temporary relief of cough associated with the common cold.
* Temporary relief of chest congestion and thinning mucus.
## Adult Dosing
Dosing varies greatly by specific product. For example, a common liquid formulation might be:
* Dextromethorphan HBr 20 mg / Guaifenesin 400 mg per 20 mL.
* Dosing: 20 mL every 4 hours as needed.
* Maximum: Do not exceed 120 mL in 24 hours.
Always refer to the specific product labeling for precise dosing instructions.
## Pediatric Dosing
Dosing varies greatly by specific product and age. Many products are **not recommended for children under 4 or 6 years of age** without physician guidance. Always check the product label for age restrictions and specific pediatric dosing recommendations.
For example, for children aged 6-11 years:
* Dextromethorphan HBr 10 mg / Guaifenesin 200 mg per 10 mL.
* Dosing: 10 mL every 4 hours as needed.
* Maximum: Do not exceed 60 mL in 24 hours.
## Dose Adjustments
No specific dose adjustments are typically required for renal or hepatic impairment based on available data for over-the-counter use, but caution is advised, especially in severe impairment. Consult a healthcare professional if you have significant kidney or liver disease.
## Contraindications
* Hypersensitivity to dextromethorphan or guaifenesin.
* Use within 14 days of starting or stopping a monoamine oxidase inhibitor (MAOI) due to the risk of serotonin syndrome with dextromethorphan.
* Use in patients with severe hepatic impairment.
* Some formulations may contain other ingredients (e.g., acetaminophen, phenylephrine) with additional contraindications.
## Adverse Effects
* **Dextromethorphan:** Drowsiness, dizziness, nausea, vomiting, constipation. High doses can cause confusion, hallucinations, respiratory depression, and seizures.
* **Guaifenesin:** Dizziness, headache, rash, nausea, vomiting.
* **Serotonin Syndrome:** Although rare with standard doses, can occur, especially when combined with other serotonergic agents. Symptoms include agitation, hallucinations, rapid heart rate, fever, sweating, shivering, muscle stiffness, and loss of coordination.
## Key Drug Interactions
* **MAOIs:** Life-threatening serotonin syndrome.
* **SSRIs, SNRIs, TCAs, triptans, opioids, buspirone, St. John's Wort:** Increased risk of serotonin syndrome.
* **CNS depressants (e.g., alcohol, benzodiazepines, sedating antihistamines):** Additive sedative effects.
* **CYP2D6 inhibitors (e.g., fluoxetine, paroxetine, quinidine):** May increase dextromethorphan levels, increasing risk of toxicity.
## Monitoring
* Monitor for effectiveness in suppressing cough and loosening mucus.
* Monitor for adverse effects, particularly drowsiness, dizziness, and signs of serotonin syndrome.
* Monitor for accidental overdose, especially in children, given the availability of numerous combination products.
## Clinical Pearls
* Combination products contain multiple active ingredients. Ensure the patient is not taking other medications with overlapping ingredients (e.g., another product containing acetaminophen or dextromethorphan).
* Guaifenesin effectiveness is controversial, and adequate hydration is often recommended as an alternative for thinning mucus.
* Dextromethorphan can be abused for its dissociative effects at high doses. Counsel patients on appropriate use.
* If symptoms persist for more than 7 days, worsen, or are accompanied by fever, rash, or severe headache, discontinue use and consult a healthcare professional.
***
*Disclaimer: This information is intended for healthcare professionals. Always consult the current official prescribing information and relevant drug compendia before making clinical decisions.*
