From the Guidelines
The recommended dose of dextromethorphan for cough is 10-15 mg tid or qid, with a maximum dose of 120 mg/d. This dosage is based on the most recent and highest quality study available, which suggests that dextromethorphan can be effective in suppressing cough in adults 1. The study provides a table of indicative doses for antitussives, demulcents, and topical anesthetics, which includes the recommended dose for dextromethorphan.
Some key points to consider when using dextromethorphan for cough include:
- Dextromethorphan works by suppressing the cough reflex in the brain rather than treating the underlying cause
- It's available in various forms, including syrups, lozenges, and extended-release formulations, with dosing varying by product
- Always check the specific product label for exact dosing instructions
- Dextromethorphan should not be used in children under 2 years, and caution is advised if taking MAO inhibitors or certain antidepressants due to potential interactions
- Side effects may include drowsiness and dizziness, so avoid driving or operating machinery until you know how it affects you
It's also important to note that other studies, such as those published in 2006, provide similar recommendations for the use of dextromethorphan for cough suppression 1. However, the most recent study from 2017 provides the most up-to-date guidance on the use of dextromethorphan for cough.
From the FDA Drug Label
Directions • shake bottle well before use • measure only with dosing cup provided • do not use dosing cup with other products • dose as follows or as directed by doctor adults and children 12 years of age and over 10 mL every 12 hours, not to exceed 20 mL in 24 hours children 6 to under 12 years of age 5 mL every 12 hours, not to exceed 10 mL in 24 hours children 4 to under 6 years of age 2.5 mL every 12 hours, not to exceed 5 mL in 24 hours children under 4 years of age do not use
The dose of dextromethorphan for cough is:
- Adults and children 12 years and over: 10 mL every 12 hours, not to exceed 20 mL in 24 hours
- Children 6 to under 12 years: 5 mL every 12 hours, not to exceed 10 mL in 24 hours
- Children 4 to under 6 years: 2.5 mL every 12 hours, not to exceed 5 mL in 24 hours
- Children under 4 years: do not use 2
From the Research
Dose of Dextromethorphan for Cough
- The dose of dextromethorphan (DM) for cough varies based on age and weight, with studies suggesting different dosages for effective cough relief 3, 4.
- For children, the administered doses are as follows:
- Ages 2 to 5 years: 7.5 mg
- Ages 6 to 11 years: 15 mg
- Ages 12 to 18 years: 30 mg resulting in a range of 0.35 to 0.94 mg/kg per dose 3.
- A study suggests that a dose of 0.5 mg/kg should be considered in future assessments of the antitussive effect of DM in pediatric studies, to balance symptomatic relief with the avoidance of adverse events 3.
- For adults, a single dose of 30 mg dextromethorphan has been studied, but the results showed little difference between the treatment groups during the study period 5.
- A combination of bilastine, dextromethorphan, and phenylephrine has been studied, with dextromethorphan dosed at 20 mg, and has been found to be efficacious, safe, non-sedating, and non-inferior to other treatments in the treatment of acute dry cough due to a common cold or allergy 6.
Adverse Events and Abuse
- Adverse events occurred most often in the high-dose group (0.60-0.94 mg/kg per dose) in a pediatric study 3.
- Dextromethorphan is subject to abuse, and when consumed at inappropriately high doses (over 1500 mg/day), it can induce a state of psychosis characterized by Phencyclidine (PCP)-like psychological symptoms, including delusions, hallucinations, and paranoia 7.