Duloxetine and Viloxazine interaction
Duloxetine and Viloxazine: both prescribing labels flag this combination with the strongest language, such as a contraindication, a boxed warning, or an instruction to avoid it.
Do not combine without a prescriber's guidance. The label language below is the strongest FDA uses.
What the FDA labels say
From the Duloxetine (Cymbalta) label · effective 2025-07-21
Inhibitors of CYP1A2 or Thioridazine : Avoid co-administration with CYMBALTA ( 5.12 )
Serotonin Syndrome Serotonin-norepinephrine reuptake inhibitors (SNRIs), including CYMBALTA, can precipitate serotonin syndrome, a potentially life-threatening condition.
Potential for Other Drugs to Affect CYMBALTA CYP1A2 Inhibitors — Co-administration of CYMBALTA with potent CYP1A2 inhibitors should be avoided [see Drug Interactions ( 7.1 )] .
Potent inhibitors of CYP1A2 should be avoided ( 7.1 )
The risk of BP decreases may be greater in patients taking concomitant medications that induce orthostatic hypotension (such as antihypertensives) or are potent CYP1A2 inhibitors [see Warnings and Precautions ( 5.12 ) and Drug Interactions ( 7.1 )] and in patients taking CYMBALTA at doses above 60 mg daily.
From the Viloxazine (QELBREE) label · effective 2025-12-05
CYP2D6 Substrates Clinical Impact Viloxazine is a weak inhibitor of CYP2D6, and increases the exposure of CYP2D6 substrates when coadministered [see Clinical Pharmacology (12.3) ] .
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Open in the checkerNot 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.