Levomilnacipran and Promethazine and dextromethorphan interaction

Levomilnacipran and Promethazine and dextromethorphan: both prescribing labels flag this combination with the strongest language, such as a contraindication, a boxed warning, or an instruction to avoid it.

Major

Do not combine without a prescriber's guidance. The label language below is the strongest FDA uses.

What the FDA labels say

From the Levomilnacipran (Fetzima) label · effective 2024-04-30

Major

Serotonin Syndrome: Increased risk when co-administered with other serotonergic agents, but also when taken alone.

Warnings and precautionsby drug classView label on DailyMed
Major

If concomitant use of FETZIMA with other serotonergic drugs is clinically warranted, inform patients of the increased risk for serotonin syndrome and monitor for symptoms.

Warnings and precautionsby drug classView label on DailyMed
Major

Examples: selegiline, tranylcypromine, isocarboxazid, phenelzine, linezolid, methylene blue Other Serotonergic Drugs Clinical Impact: Concomitant use of FETZIMA with other serotonergic drugs increases the risk of serotonin syndrome.

Drug interactionsby drug classView label on DailyMed
Major

Intervention: Monitor for symptoms of serotonin syndrome when FETZIMA is used concomitantly with other drugs that may affect the serotonergic neurotransmitter systems.

Drug interactionsby drug classView label on DailyMed
Moderate

The risk is increased with concomitant use of other serotonergic drugs (including triptans, tricyclic antidepressants, fentanyl, lithium, tramadol, meperidine, methadone, tryptophan, buspirone, amphetamines, and St.

Warnings and precautionsby drug classView label on DailyMed

From the Promethazine and dextromethorphan (Promethazine Hydrochloride and Dextromethorphan Hydrobromide) label · effective 2025-08-08

Major

…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.

Drug interactionsby drug classView label on DailyMed
Moderate

…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…

Warningsby drug classView label on DailyMed

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Not medical advice. Interaction Checker quotes FDA label text and NIH fact sheets. Whether an interaction matters for you depends on doses, timing, kidney and liver function, and other conditions. Confirm with a pharmacist or prescriber.