Acetaminophen and Isoniazid interaction
Acetaminophen and Isoniazid: the Isoniazid prescribing label describe an interaction that usually calls for monitoring, a dose change, or spacing the doses.
Usually manageable with monitoring or a dose change. Tell your pharmacist you take both.
What the FDA labels say
From the Isoniazid label · effective 2026-04-27
Acetaminophen A report of severe acetaminophen toxicity was reported in a patient receiving isoniazid.
It is believed that the toxicity may have resulted from a previously unrecognized interaction between isoniazid and acetaminophen and a molecular basis for this interaction has been proposed.
Studies have demonstrated that pretreatment with isoniazid potentiates acetaminophen hepatotoxicity in rats 1,2 .
Furthermore it has been proposed that isoniazid resulted in induction of P-450IIE1 in the patient's liver which, in turn, resulted in a greater proportion of the ingested acetaminophen being converted to the toxic metabolites.
Taking more than these two? Interactions stack. Check your whole list at once; it stays in your browser.
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.