Phenelzine and Promethazine and dextromethorphan interaction

Phenelzine sulfate should not be used in combination with dextromethorphan or with CNS depressants such as alcohol and certain narcotics.

OTC Medications To Avoid Cold and cough preparations (including those containing dextromethorphan) Nasal decongestants (tablets, drops, or spray) Hay-fever medications Sinus medications Asthma inhalant medications Antiappetite medicines Weight-reducing preparations "Pep" pills L-tryptophan containing preparations Also, certain prescription drugs should be avoided.

Patients should be warned that the use of the above foods, beverages, or medications may cause a reaction characterized by headache and other serious symptoms due to a rise in blood pressure, with the exception of dextromethorphan which may cause reactions similar to those seen with meperidine.

Also, there has been a report of an interaction between phenelzine sulfate and dextromethorphan (ingested as a lozenge) causing drowsiness and bizarre behavior.

Dextromethorphan should not be used in patients receiving a monoamine oxidase inhibitor (see PRECAUTIONS – Drug Interactions ).

Drug Interactions Monoamine Oxidase (MAO) Inhibitors – Hyperpyrexia, hypotension, and death have been reported coincident with the co-administration of monoamine oxidase (MAO) inhibitors and products containing dextromethorphan.

Thus, concomitant administration of Promethazine Hydrochloride and Dextromethorphan Hydrobromide Oral Solution and MAO inhibitors should be avoided (see CONTRAINDICATIONS ).

…prolong, or intensify the sedative action of other central-nervous-system depressants, such as alcohol, sedatives/hypnotics (including barbiturates), narcotics, narcotic analgesics, general anesthetics, tricyclic antidepressants, and tranquilizers; therefore, such agents should be avoided or administered in reduced dosage to patients receiving promethazine.

…concomitant use of other central-nervous-system depressants such as alcohol, sedatives/hypnotics (including barbiturates), narcotics, narcotic analgesics, general anesthetics, tricyclic antidepressants, and tranquilizers; therefore such agents should either be eliminated or given in reduced dosage in the presence of promethazine (see PRECAUTIONS – Information for Patients…