Clobazam and Isoniazid interaction
Clobazam and Isoniazid: 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 Isoniazid label · effective 2026-04-27
To avoid phenytoin intoxication, appropriate adjustment of the anticonvulsant should be made 5,6 .
Carbamazepine levels should be determined prior to concurrent administration with isoniazid, signs and symptoms of carbamazepine toxicity should be monitored closely, and appropriate dosage adjustment of the anticonvulsant should be made 3 .
From the Clobazam (SYMPAZAN) label · effective 2025-12-01
Strong or Moderate CYP2C19 Inhibitors: Dosage adjustment of SYMPAZAN ® may be necessary ( 7.4 )
Effect of Other Drugs on SYMPAZAN ® Strong and Moderate Inhibitors of CYP2C19 Coadministration with strong or moderate inhibitors of CYP2C19 may result in increased exposure to N-desmethylclobazam, the active metabolite of clobazam.
Dosage adjustment of SYMPAZAN ® may be necessary when co-administered with strong CYP2C19 inhibitors (e.g., fluconazole, fluvoxamine, ticlopidine) or moderate CYP2C19 inhibitors (e.g., omeprazole) [see Clinical Pharmacology (12.3) ].
Effect of Cannabidiol on SYMPAZAN ® Coadministration of cannabidiol, a CYP3A4 and CYP2C19 substrate and a CYP2C19 inhibitor, with clobazam may increase the risk of clobazam-related adverse reactions [ see Warnings and Precautions (5.4, 5.5) , 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.