Fluoxetine and Isoniazid interaction
Fluoxetine and Isoniazid: the Fluoxetine prescribing label 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 Fluoxetine (Prozac) label · effective 2026-01-08
Serotonin Syndrome and MAOIs: Do not use MAOIs intended to treat psychiatric disorders with PROZAC or within 5 weeks of stopping treatment with PROZAC.
Do not use PROZAC within 14 days of stopping an MAOI intended to treat psychiatric disorders.
Monoamine Oxidase Inhibitors (MAOIs) The use of MAOIs intended to treat psychiatric disorders with PROZAC or within 5 weeks of stopping treatment with PROZAC is contraindicated because of an increased risk of serotonin syndrome.
The use of PROZAC within 14 days of stopping an MAOI intended to treat psychiatric disorders is also contraindicated [see Dosage and Administration ( 2.9 ) and Warnings and Precautions ( 5.2 )] .
Starting PROZAC in a patient who is being treated with MAOIs such as linezolid or intravenous methylene blue is also contraindicated because of an increased risk of serotonin syndrome [see Dosage and Administration ( 2.10 ) and Warnings and Precautions ( 5.2 )] .
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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.