MAJOR — Use With Caution
DANGEROUS — duloxetine both raises DXM levels and adds serotonin
Evidence level: STRONG
Cymbalta raises DXM levels and adds serotonin risk — do not combine.
Duloxetine is an SNRI and moderate CYP2D6 inhibitor. DXM is serotonergic and CYP2D6 substrate. Both elevated DXM levels and serotonin syndrome risk.
Avoid DXM-containing products while on duloxetine.
Take Duloxetine at the same time each day — most people prefer morning with breakfast. Dextromethorphan follows its prescribed schedule. SNRIs can affect blood pressure (both up and down), so monitor BP if combining with cardiovascular medications.
CYP2D6 poor metabolizers, high duloxetine dose
Agitation, confusion, rapid heart rate, muscle twitching, hyperthermia
Inform prescriber about all cough/cold products.
Discuss this combination with your prescriber. They may adjust timing, dosing, or switch to an alternative with fewer interaction risks. Never stop an antidepressant abruptly — taper under medical guidance.
Cymbalta raises DXM levels and adds serotonin risk — do not combine.
Take Duloxetine at the same time each day — most people prefer morning with breakfast. Dextromethorphan follows its prescribed schedule. SNRIs can affect blood pressure (both up and down), so monitor BP if combining with cardiovascular medications.
Agitation, confusion, rapid heart rate, muscle twitching, hyperthermia
Discuss this combination with your prescriber. They may adjust timing, dosing, or switch to an alternative with fewer interaction risks. Never stop an antidepressant abruptly — taper under medical guidance.
Inform prescriber about all cough/cold products.
Or browse the full interaction database (121,000+ pairs).