Alcohol Content in Promethazine-Dextromethorphan Formulations
Some formulations of promethazine-dextromethorphan cough syrup do contain alcohol, but many modern formulations are alcohol-free—you must check the specific product label to determine alcohol content.
Key Points About Alcohol Content
- Dextromethorphan extended-release formulations are explicitly labeled as "alcohol-free" 1
- The presence of alcohol varies by manufacturer and specific product formulation, making it essential to review the package labeling for each individual product 1
- Historically, many cough syrups contained alcohol as a solvent and preservative, but contemporary formulations increasingly omit alcohol 1
Clinical Significance of Alcohol Content
Drug Interactions and CNS Depression
- Promethazine's hypnotic and sedative effects are significantly increased when combined with alcohol or other CNS depressants such as benzodiazepines and opioid narcotics 2
- The American Gastroenterological Association warns that promethazine can cause respiratory depression, particularly when combined with other CNS depressants including alcohol 3
- Diphenhydramine (a related antihistamine) demonstrates increased hypnotic effects when given in combination with alcohol, a property likely shared by promethazine given their similar pharmacologic profiles 2
Abuse Potential Considerations
- Promethazine-containing cough syrups have documented misuse and abuse potential, particularly in adolescents and young adults, with European data showing 557 abuse/misuse/dependence-related adverse drug reactions between 2003-2019 4
- Dextromethorphan is a known drug of abuse with dissociative properties due to its NMDA receptor antagonist activity 5, 6
- The concomitant use of dextromethorphan and alcohol causes enhanced dissociation and can produce acute psychotic symptoms that may be difficult to distinguish from alcohol withdrawal 5
Important Clinical Caveats
Patient Populations Requiring Caution
- Patients with alcohol dependence or substance use disorders should be counseled about the risks of using dextromethorphan-containing products, as these can interact dangerously with alcohol 5, 6
- The American Geriatrics Society recommends caution with dextromethorphan/quinidine combinations in older adults due to limited efficacy and increased fall risk 2
- Healthcare providers should be vigilant about promethazine misuse, as it is associated with drug-related fatalities, particularly when combined with opioids 4
Practical Recommendations
- Always verify the specific formulation's alcohol content by reading the product label before prescribing or recommending to patients 1
- For patients who must avoid alcohol (recovering alcoholics, patients on disulfiram, religious/cultural reasons, children), specifically select and verify alcohol-free formulations 1
- Consider that even "alcohol-free" formulations carry risks of abuse and CNS depression when promethazine and dextromethorphan are combined 4, 7