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 label · effective 2026-03-02
Serotonin Syndrome Serotonin-norepinephrine reuptake inhibitors (SNRIs), including Duloxetine Delayed-Release Capsules, can precipitate serotonin syndrome, a potentially life-threatening condition.
Strong CYP1A2 inhibitors : Avoid concomitant use.
Strong CYP1A2 Inhibitors Prevention or Management Avoid concomitant use of Duloxetine Delayed-Release Capsules with strong CYP1A2 inhibitors [see Clinical Pharmacology ( 12.3 )].
CYP2D6 Poor Metabolizers Using Strong Inhibitor of CYP1A2 Prevention or Management Avoid co-administration of Duloxetine Delayed-Release Capsules and strong CYP1A2 inhibitors in patients who are CYP2D6 poor metabolizers [see Clinical Pharmacology ( 12.3 )] .
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 Drug Interactions ( 7.1 )] and in patients taking duloxetine delayed-release capsules 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.