Acetaminophen Injection and Carbamazepine: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Jul 10, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Carbamazepine
Acetaminophen Injection
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
An increased risk of acetaminophen hepatotoxicity and reduced acetaminophen exposure
Interaction Deep Dive
Coadministration of carBAMazepine and acetaminophen may result in reduced acetaminophen exposure. If coadministering, closely monitor acetaminophen levels and adjust the acetaminophen dosage as needed12. The hepatotoxicity of acetaminophen may be related to the formation of toxic metabolites in the liver. When carBAMazepine, an enzyme inducer, is given concurrently with high and frequent doses of acetaminophen, the induction of the metabolism of acetaminophen may result in an increased level of hepatotoxic metabolites. In support of this theory, it has been observed that patients who receive enzyme-inducing agents do not recover as well from an acetaminophen overdose as patients who are not taking enzyme-inducing drugs. The significance of this interaction at therapeutic doses of acetaminophen administered intermittently appears low. In addition, acetaminophen has been shown to have lower bioavailability in epileptic patients receiving enzyme-inducing agents 3.
Why it happens (mechanism)
Increased metabolism of acetaminophen resulting in abnormally high levels of hepatotoxic metabolites; unknown
Literature reports
1 report — tap to read
a) A 17-year-old female with a history of anorexia nervosa and who was receiving carBAMazepine 300 mg daily for mood stabilization ingested acetaminophen 7800 mg in a suicide attempt. Upon admission to the hospital, her liver function tests were significantly elevated and her serum acetaminophen level was 15 mcg/mL. Treatment with acetylcysteine was initiated and her acetaminophen level decreased in the expected manner. However, eight days later, she underwent a liver transplant because of fulminant hepatic failure that was believed to be due to a combination of low body weight, malnutrition, and carBAMazepine therapy. A small portion of acetaminophen is metabolized by the cytochrome P450 system to toxic metabolites which are then detoxified by glutathione. CarBAMazepine is known to induce the cytochrome P450 system, and her malnutrition status depleted her glutathione concentrations. These two factors resulted in a greater concentration of acetaminophen toxic metabolites, resulting in liver failure 4.
Common questions
Can I take Acetaminophen Injection and Carbamazepine together?
An increased risk of acetaminophen hepatotoxicity and reduced acetaminophen exposure Always confirm with your pharmacist or prescriber before making any change.
How serious is the Acetaminophen Injection and Carbamazepine interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "delayed". Effects tend to build up gradually over days to weeks.
How strong is the evidence for this interaction?
The evidence is graded "probable". Good supporting evidence, though not definitively proven.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Acetaminophen Injection or Carbamazepine need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there a safer alternative to one of these medications for me?
References (4)
- Product Information: Tegretol(R)-XR oral extended-release tablets, carbamazepine oral extended-release tablets. Novartis Pharmaceuticals Corporation (per FDA), East Hanover, NJ, 2023. DailyMed
- Product Information: Tegretol(R) oral chewable tablets, oral tablets, oral suspension, carbamazepine oral chewable tablets, oral tablets, oral suspension. Novartis Pharmaceuticals Corporation (per FDA), East Hanover, NJ, 2023. DailyMed
- Perucca E & Richens A: Paracetamol disposition in normal subjects and in patients treated with antiepileptic drugs. Br J Clin Pharmacol 1979; 7:201-206. PubMed
- Young CR & Mazure CM: Fulminant hepatic failure from acetaminophen in an anorexic patient treated with carbamazepine (letter). J Clin Psychiatry 1998; 59:622. DOI
Keep reading about Carbamazepine
Keep reading about Acetaminophen Injection
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Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
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