Loratadine and Amiodarone: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Amiodarone
Loratadine
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
Increased risk of QT interval prolongation and torsade de pointes
Interaction Deep Dive
Both amiodarone and loratadine are metabolized by CYP3A4 isozymes. Additionally, amiodarone is also a CYP3A4 inhibitor1. QT interval prolongation and torsades de pointes has been reported with the coadministration of amiodarone and loratadine 23. Caution is advised if these agents are coadministered. Prior to using these agents concurrently, consider obtaining a baseline ECG and repeating it several hours after ingestion of the first dose. If QT interval prolongation or dispersion is observed, loratadine should be discontinued and rhythm monitoring should be initiated 2.
Why it happens (mechanism)
Unknown
Literature reports
1 report — tap to read
a) A case report described QT interval prolongation and torsades de pointes in a 73-year-old woman following concomitant administration of amiodarone and loratadine. The woman, who had a history of hypertension and hyperlipidemia, was on chronic amiodarone therapy (200 mg/day) for paroxysmal atrial fibrillation and had a baseline QT interval of 400 milliseconds. Additional medications included cilaprazil, pravastatin, and warfarin. A few days after receiving loratadine 10 mg/day for a suspected allergic reaction, the patient had a syncopal episode. Physical/neurological exams, and cardiac enzymes, liver, and renal function tests were normal. A transthoracic echocardiogram showed normal systolic left ventricular function, mild left ventricular hypertrophy, and significant diastolic dysfunction. Rhythm monitoring revealed sinus bradycardia, long QT interval (720 milliseconds), with long-short QRS cycles followed by one of multiple episodes of torsades de points (TdP) that were self-terminated. Subsequently, amiodarone and loratadine were discontinued. The patient became asymptomatic over the next 4 days and the QT interval and dispersion returned to normal baseline 2. A chart review of 6 patients revealed an additional case of syncope and TdP in a 74-year old woman following addition of loratadine (10 mg/day) to chronic amiodarone therapy (200 mg/day) for paroxysmal atrial fibrillation. In this patient, TdP occurred 2 days following ingestion of loratadine 3.
Common questions
Can I take Loratadine and Amiodarone together?
Increased risk of QT interval prolongation and torsade de pointes Always confirm with your pharmacist or prescriber before making any change.
How serious is the Loratadine and Amiodarone interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
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 Loratadine or Amiodarone 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 (3)
- Product Information: CORDARONE(R) oral tablets, amiodarone hcl oral tablets. Wyeth Pharmaceuticals,Inc, Philadelphia, PA, 2006. DailyMed
- Atar S, Freedberg NA, Antonelli D, et al: Torsades de pointes and QT prolongation due to a combination of loratadine and amiodarone. Pacing Clin Electrophysiol 2003; 26(3):785-786. PubMed
- Antonelli D, Atar S, Freedberg NA, et al: Torsade de pointes in patients on chronic amiodarone treatment: contributing factors and drug interactions. Isr Med Assoc J 2005; 7(3):163-165.
Keep reading about Amiodarone
Keep reading about Loratadine
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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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