What is dextromethorphan?

Dextromethorphan: A Non-Opioid Cough Suppressant

Dextromethorphan is a non-sedating opiate that acts centrally to suppress the cough reflex and is the preferred first-line pharmacological treatment for non-productive cough due to its efficacy and superior safety profile compared to other antitussives. 1, 2

Mechanism of Action and Formulation

• Dextromethorphan works by centrally modulating the cough reflex, with a clear dose-response relationship 1
• It is available as dextromethorphan hydrobromide or as dextromethorphan polistirex in extended-release formulations 3
• The FDA-approved formulation contains dextromethorphan polistirex equivalent to 30 mg dextromethorphan hydrobromide per 5 mL 3

Clinical Uses

• Temporarily relieves cough due to minor throat and bronchial irritation, such as from the common cold or inhaled irritants 3
• Helps suppress the impulse to cough to aid with sleep 3
• Maximum cough reflex suppression occurs at 60 mg, which is higher than typical over-the-counter dosing 1, 2
• Standard over-the-counter dosing is often subtherapeutic for optimal cough suppression 2

Efficacy

• Dextromethorphan has been shown to effectively suppress acute cough in meta-analyses 1, 4
• At 20 mg doses, it has similar efficacy to codeine in reducing cough frequency but is superior in reducing cough intensity 5
• Extended-release formulations can provide up to 12 hours of cough relief 3

Safety Profile and Considerations

• Dextromethorphan has a better safety profile than codeine and other opioid antitussives 1, 4
• Adverse reactions are infrequent and usually not severe, primarily including neurological, cardiovascular, and gastrointestinal disturbances 6
• Caution should be exercised with combination products that may contain additional ingredients like pain relievers 1, 2
• Dextromethorphan should not be used concurrently with monoamine oxidase inhibitors (MAOIs) due to potential drug interactions 6

Potential for Misuse

• At inappropriately high doses (over 1500 mg/day), dextromethorphan can induce psychosis with PCP-like symptoms including delusions, hallucinations, and paranoia 7
• Recreational use, sometimes called "Robotripping," involves consuming supra-therapeutic amounts for psychoactive effects 8
• Dextromethorphan is not detected on standard urine drug screens, which may contribute to its appeal for recreational use 7
• With chronic misuse, tolerance and withdrawal symptoms have been reported 8

Practical Approach to Using Dextromethorphan

• For benign viral cough, start with non-pharmacological approaches like honey and lemon before considering dextromethorphan 2, 4
• When pharmacological treatment is needed, dextromethorphan at appropriate doses (30-60 mg) is the preferred option 1, 2
• For nighttime cough disrupting sleep, consider dextromethorphan or first-generation antihistamines with sedative properties 1, 2
• Avoid codeine-containing products as they offer no advantage over dextromethorphan but have more side effects 1, 4

Common Pitfalls to Avoid

• Using subtherapeutic doses that may not provide adequate relief (optimal dose is 60 mg for maximum cough suppression) 1, 2
• Failing to recognize potential for abuse, especially in adolescents and young adults 7, 8
• Not checking for drug interactions, particularly with MAOIs 6
• Using dextromethorphan for productive cough where clearance of secretions is beneficial 2