Phenobarbital and Trazodone interaction
Phenobarbital and Trazodone: 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 Phenobarbital (SEZABY) label · effective 2025-12-23
Drugs that Prolong the QT Interval : Avoid concomitant use.
QT Prolongation SEZABY may prolong the QT interval [see Clinical Pharmacology (12.2)] .
Drugs that Prolong QT Interval SEZABY may prolong the QT interval [see Warnings and Precautions (5.10) and Clinical Pharmacology (12.2)] .
Other products that may also prolong the QTc interval may have additive effects, and products that may increase concentrations of phenobarbital [see Drug Interactions (7.1)] may increase the QT prolongation risk; therefore, avoid concomitant use of SEZABY and these products.
From the Trazodone (RALDESY TM) label · effective 2026-09-01
CNS Depressants: RALDESY may enhance effects of alcohol, barbiturates, or other CNS depressants ( 7 ).
CYP3A4 Inducers: Increase in RALDESY dosage may be necessary ( 2.5 , 7 ).
Strong CYP3A4 Inducers Clinical Impact: The concomitant use of RALDESY and strong CYP3A4 inducers decreased the exposure of trazodone compared to the use of RALDESY alone.
Intervention: Patients should be closely monitored to see if there is a need for an increased dose of RALDESY when taking CYP3A4 inducers [see Dosage and Administration (2.5) ].
Central Nervous System (CNS) Depressants Clinical Impact: RALDESY may enhance the response CNS depressants.
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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.