4 known interactions • 1 major • 3 moderate • 0 minor
Always disclose all medications to your healthcare providers — prescription medicines, OTC medications, vitamins, and herbal supplements. This list may not include every possible interaction. Use our Medicine Interaction Checker to screen your complete medication list.
Potentially life-threatening or causing permanent damage. Avoid combination.
May worsen condition or require dose adjustment. Monitor closely.
Usually limited clinical effect. Manage with routine monitoring.
Alcohol (chronic heavy use, >3 drinks/day)
Chronic alcohol induces CYP2E1, increasing NAPQI production from acetaminophen, depleting glutathione faster and increasing hepatotoxicity risk even at therapeutic doses.
Management: Limit to 2,000mg/day maximum in heavy drinkers; counsel patients on risks.
Warfarin
Regular acetaminophen use (>2g/day for >1 week) can increase INR in warfarin patients, increasing bleeding risk.
Management: Monitor INR if patient begins regular acetaminophen use; use lowest effective dose.
Isoniazid
Isoniazid induces CYP2E1, increasing NAPQI production. Additive hepatotoxicity risk.
Management: Avoid regular acetaminophen use during isoniazid therapy when possible; monitor LFTs.
Carbamazepine / phenytoin / rifampin
Hepatic enzyme inducers increase conversion of acetaminophen to hepatotoxic NAPQI metabolite.
Management: Reduce maximum acetaminophen dose; monitor for hepatotoxicity.
Always ask your pharmacist about potential interactions with food, alcohol, and supplements specific to Acetaminophen. Some medicines have significant interactions with grapefruit juice, high-fat meals, dairy products, or vitamin K-rich foods.