Amiodarone
Pronunciation: pronunciation varies by local usage.
- Generic name
- amiodarone
- Brand names
- Cordarone, Pacerone, Cordarone X
- Drug class
- Class III antiarrhythmic agent (US classification); also a Class I and III antiarrhythmic (UK ATC) with properties of all four Vaughan-Williams classes
- Form
- Tablet (200 mg tablets documented in UK product information; US tablet strength not separately established in the sources reviewed for this page)
- Route
- Oral
- Legal status
- Prescription-only medicine
Availability and supply rules vary by country
Trade names by country: United States
Australia: · Full directory
What amiodarone is and how it works
Amiodarone is an antiarrhythmic medicine used for serious heart rhythm disorders. It has properties of all four Vaughan-Williams antiarrhythmic classes. In the US, it is reserved for documented life-threatening ventricular arrhythmias because of its substantial toxicity; in the UK, it is used for severe rhythm disorders not responding to other therapies. (1) (2)
Indications and dosing regimens differ between the United States and the United Kingdom. In the US, it is reserved for recurrent ventricular fibrillation and hemodynamically unstable ventricular tachycardia. In the UK, it may be used for a broader range of severe rhythm disorders not responding to other therapies. Amiodarone carries risks of significant toxicity involving the lungs, liver, thyroid, eyes, skin, and heart rhythm itself, and has many drug interactions.
Mechanism of action: how amiodarone works
Amiodarone is a class III antiarrhythmic that prolongs the cardiac action potential and refractory period by blocking potassium channels; it also has class I (sodium-channel block) effects. Not established from the sources reviewed: specific beta-adrenergic-block (class II) and calcium-channel-block (class IV) mechanistic details were not separately established in the sources reviewed for this page, beyond the general classification of amiodarone as having properties of all four Vaughan-Williams classes. Oral bioavailability is approximately 50%, with peak plasma concentrations at 3–7 hours. The parent drug has a mean elimination half-life of 53 days (range 26–107 days); the active metabolite desethylamiodarone has a half-life of about 61 days. Steady state without loading doses may take 130–535 days. Volume of distribution is about 60 L/kg, indicating extensive tissue accumulation. Metabolism is hepatic via CYP3A and CYP2C8; excretion is primarily biliary with negligible renal elimination. (1) (2)
What amiodarone is used for
Recurrent ventricular fibrillation or hemodynamically unstable ventricular tachycardia (United States)
Amiodarone is reserved for documented, life-threatening ventricular arrhythmias because of its substantial toxicity. Whether specific prior treatment or tolerability requirements apply was not established in the sources reviewed for this page; this is determined by the treating clinician. (1)
Severe rhythm disorders not responding to other therapies (United Kingdom)
Amiodarone is indicated for treatment of severe rhythm disorders not responding to other therapies, including atrial flutter and fibrillation, paroxysmal supraventricular tachycardias, and arrhythmias associated with Wolff-Parkinson-White syndrome. (2)
Before taking amiodarone
Do not take / not appropriate for
- Cardiogenic shock, sick sinus syndrome, or second- or third-degree atrioventricular block (without a functioning pacemaker) are US contraindications. Tell your prescriber if any of these apply to you. (US only) (1)
- Sinus bradycardia, sino-atrial block, or severe conduction disturbances (without a functioning pacemaker) are UK contraindications. Tell your prescriber if this applies to you. (UK only) (2)
- Known hypersensitivity to amiodarone, iodine, or any excipient is a contraindication. Tell your prescriber about any previous allergic reaction before starting treatment. (all products) (1) (2)
- Thyroid dysfunction is a UK contraindication; in the US, thyroid disease requires careful monitoring rather than being a contraindication. Tell your prescriber about any thyroid condition so they can determine whether amiodarone is appropriate for you. (UK only) (2) (1)
- Pregnancy and breastfeeding require specialist discussion (contraindicated in the UK; in the US, amiodarone may cause fetal harm and breastfeeding is not recommended). Tell your clinician if you are pregnant, planning pregnancy, or breastfeeding so they can advise on your specific situation. (all products) (1) (2)
- Other medicines that can cause Torsades de Pointes or QT prolongation require clinician review before combining with amiodarone. Tell your prescriber about all medicines you take so they can assess whether any need to be avoided or adjusted. (all products) (1) (2)
Tell your clinician about
- Any history of thyroid disease, lung problems, liver disease, or bradycardia.
- All current medicines, including warfarin, digoxin, statins (simvastatin, lovastatin), flecainide, sofosbuvir-containing hepatitis C treatments, and any drugs that affect heart rhythm.
- If you are pregnant, planning pregnancy, or breastfeeding.
- Any previous allergic reaction to iodine or to amiodarone itself.
- Any eye problems or changes in vision (because amiodarone can affect the eyes).
How to take amiodarone
- Take amiodarone exactly as prescribed. Dosing schedules are complex and differ between the United States and the United Kingdom.
- In the US, for life-threatening ventricular arrhythmias, a typical loading dose is 800–1600 mg per day for 1–3 weeks, followed by a transition dose of 600–800 mg per day for one month, then a maintenance dose of 400 mg per day; whether the loading dose is given in divided amounts was not established in the sources reviewed.
- In the UK, for severe arrhythmias, a typical loading dose is 200 mg three times a day for one week, then 200 mg twice daily for a further week, then a maintenance dose of 200 mg daily (or less, depending on response).
- Any dose reduction, discontinuation, or schedule change is a decision made by your prescribing clinician based on your individual monitoring results.
- Because of the risk of serious side effects, regular medical monitoring (lung, liver, thyroid, eye, heart) is required both before starting and throughout treatment.
Procedures and treatment changes
Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (1) (2)
Missed dose
Contact your prescribing clinician for individual advice if a dose is missed.
Overdose
Amiodarone has an extremely long half-life (mean 53 days), documented as pharmacokinetic information only — this is not linked to a specific overdose-management instruction in the sources reviewed. If you suspect an overdose, seek emergency medical attention immediately.
Side effects
Amiodarone can affect many organs. Regular monitoring is needed to detect problems early. The most common side effects include gastrointestinal disturbances, corneal microdeposits, photosensitivity, and thyroid changes. Serious lung, liver, and heart rhythm toxicity can occur.
Gastrointestinal effects
What to notice: Nausea, vomiting, altered taste (dysgeusia). These are very common, especially during the initial high-dose loading phase.
What to do: Report severe or persistent symptoms to your clinician. (1) (2)
Corneal microdeposits
What to notice: Usually only seen with a slit-lamp eye examination. They are very common.
What to do: Report any visual changes. Regular ophthalmologic examination is recommended (annually per UK guidance; the US label advises regular examination without a specified interval). (1) (2)
Photosensitivity
What to notice: Increased sensitivity to sunlight, leading to easy sunburn. Reported in about 10% of patients per the US label; described as very common per the UK SmPC.
What to do: Avoid excessive sun exposure and report any concerning skin reactions to your clinician. (1) (2)
Thyroid dysfunction
What to notice: Symptoms of hypothyroidism (e.g., fatigue, weight gain, cold intolerance) or hyperthyroidism (e.g., palpitations, weight loss, heat intolerance, sweating). Hypothyroidism occurs in up to 10% of patients, hyperthyroidism in about 2%.
What to do: Thyroid function is monitored before treatment and periodically during treatment (every 6 months per UK guidance; baseline and periodic testing per US labeling). Report any new symptoms to your clinician. (1) (2)
Bradycardia
What to notice: Noticeably slow heart rate, fatigue, dizziness, fainting. This is common and dose-related.
What to do: Report symptoms promptly. Your electrocardiogram (ECG) will be monitored during treatment. (1) (2)
Skin discoloration
What to notice: A blue-gray or slate-gray pigmentation of areas exposed to sunlight. This can occur with prolonged high-dose therapy.
What to do: Discuss any skin changes with your clinician. (1) (2)
Pulmonary toxicity (lung problems)
What to notice: New or worsening cough or shortness of breath. Pulmonary toxicity can occur at any time and can be fatal.
What to do: Contact your clinician immediately for evaluation, which may include a chest X-ray and pulmonary function tests. (1) (2)
Liver injury
What to notice: A specific symptom list was not established in the sources reviewed for this page; liver enzyme elevations are common and are detected through routine blood testing rather than symptoms alone.
What to do: Liver function tests are monitored regularly. Report any new or unusual symptoms to your clinician; whether your dose needs to be reduced or the medicine stopped is a decision for your treating clinician. (1) (2)
Optic neuropathy
What to notice: Blurred vision, decreased visual acuity, or visual field changes. This can occur at any time and may progress to permanent blindness.
What to do: Seek prompt ophthalmologic evaluation. Whether to stop amiodarone is a decision for your treating clinician. (1) (2)
Worsening of arrhythmia
What to notice: Palpitations, chest pain, syncope (fainting), feeling of abnormal heart beats. Amiodarone can cause new or worsened arrhythmias, which may be life-threatening.
What to do: Continuous ECG monitoring is standard during treatment initiation. Call emergency services if severe. (1) (2)
Serious warnings
Pulmonary toxicity — emergency
Symptoms: New or worsening cough or shortness of breath (dyspnea).
Action: Seek immediate medical attention. Pulmonary toxicity can be fatal and is a known major toxicity of amiodarone. (1) (2)
Hepatotoxicity — emergency
Symptoms: Liver enzyme elevations are detected through routine blood testing.
Action: Seek medical evaluation promptly. Liver injury can be severe and life-threatening. (1) (2)
Proarrhythmia — emergency
Symptoms: Palpitations, fainting, chest pain, sudden collapse.
Action: Amiodarone can cause new or worsened arrhythmias, including life-threatening ventricular arrhythmias. Continuous ECG monitoring is required at initiation. Call emergency services if symptoms occur. (1) (2)
Optic neuropathy — urgent
Symptoms: Blurred vision or visual loss.
Action: Seek urgent ophthalmologic evaluation. Optic neuropathy can progress to permanent blindness. The UK label states amiodarone should be withdrawn if this occurs; in either region, whether to continue or stop treatment is an urgent decision made by your treating clinician. (1) (2)
Interactions
| Medicine or test | Effect | Action |
|---|---|---|
| Warfarin | Amiodarone increases the anticoagulant effect of warfarin; prothrombin time typically increases by about 100% after 3–4 days. | Your prescriber manages any warfarin dose adjustment (typically a reduction of one-third to one-half) and will arrange closer INR monitoring. (1) (2) |
| Digoxin | Amiodarone increases digoxin plasma concentration by about 70%, increasing the risk of digoxin toxicity. | Your prescriber manages any digoxin dose adjustment (typically a reduction by half, or discontinuation) and will arrange digoxin level monitoring. (1) (2) |
| Statins metabolized by CYP3A4 (e.g., simvastatin, lovastatin) | Increased risk of muscle damage (myopathy/rhabdomyolysis). | Your prescriber manages any statin dose limit (the US label specifies simvastatin 20 mg/day and lovastatin 40 mg/day); whether switching to an alternative statin is appropriate is a clinician decision not specified in the sources reviewed for this page. (1) (2) |
| QT-prolonging drugs (e.g., certain antiarrhythmics, antipsychotics, antibiotics) | Additive risk of Torsades de Pointes and life-threatening arrhythmias. | The US label advises avoiding concomitant use; the UK label lists it as contraindicated. Your prescriber makes the final decision for your situation. (1) (2) |
| Negative chronotropic drugs (e.g., beta-blockers, calcium channel blockers) | Potentiation of bradycardia, sinus arrest, and atrioventricular block. | Your prescriber decides whether dose adjustments or additional ECG monitoring are needed. (1) |
| Flecainide | The UK label recommends a dose reduction for concurrent use. | Your prescriber manages any flecainide dose adjustment (the UK label specifies a reduction of about 50%) and arranges closer monitoring. (2) |
| Sofosbuvir-containing hepatitis C regimens | Risk of serious symptomatic bradycardia. | The UK label states coadministration is not recommended. Your prescriber makes the final decision for your situation. (2) |
| Amiodarone inhibits CYP1A2, CYP2C9, CYP2D6, CYP3A, and P-glycoprotein; it is a substrate of CYP3A and CYP2C8. | This enzyme/transporter interaction can alter the levels of other drugs metabolized through these pathways. | Review all concomitant medications with the prescriber; dose adjustments of other drugs may be necessary. (1) |
Pregnancy, breastfeeding, kidney/liver function, age
Pregnancy
Amiodarone may cause fetal harm, including neonatal bradycardia, hypothyroidism, and neurodevelopmental abnormalities. In the UK, it is contraindicated except in exceptional circumstances. Discuss all risks with your specialist. (1) (2)
Breastfeeding
Amiodarone passes into breast milk in significant amounts (reported as 3.5% to 45% of the maternal dose in US labeling). Breastfeeding is contraindicated in the UK and not recommended in the US. Discuss feeding and treatment options with your clinician if amiodarone is needed while breastfeeding. (1) (2)
Geriatric patients
Older patients may have lower drug clearance and an increased half-life. Treatment should start at the lower end of the dosing range, with careful monitoring for bradycardia and other side effects. (1)
Children
No specific pediatric dosing information was captured in this research pass. Use in children requires specialist guidance.
Monitoring
Before starting
- Obtain a baseline chest X-ray and pulmonary function tests, including diffusion capacity.
- Measure liver transaminases (ALT, AST) to establish baseline.
- Check thyroid function (TSH, free T4) before therapy.
- Perform a baseline ECG and serum potassium level.
- Conduct a comprehensive ophthalmologic examination (funduscopy and slit-lamp).
- Review all concomitant medications for potential interactions.
- Confirm the indication is appropriate per regional labeling; in the US, amiodarone should be reserved for documented life-threatening ventricular arrhythmias.
During treatment
- Repeat chest X-ray and pulmonary function tests (every 3–6 months or if respiratory symptoms develop, per US labeling; the UK source supports a baseline chest X-ray with repeat imaging if pulmonary toxicity is suspected).
- Monitor liver transaminases periodically (every 6 months per UK guidance); if they exceed three times the upper limit of normal, your treating clinician will decide whether to reduce the dose or discontinue amiodarone.
- Check thyroid function periodically (every 6 months and for several months after discontinuation per UK guidance; baseline and periodic testing per US labeling). Watch for clinical signs of hypo- or hyperthyroidism.
- Obtain regular ophthalmologic examinations (annually per UK guidance; regular examination without a specified interval per the US label). If optic neuropathy is suspected, urgent ophthalmologic evaluation is needed and your treating clinician decides whether amiodarone should be discontinued.
- Perform continuous ECG monitoring during treatment initiation. Monitor for bradycardia, AV block, and new or worsened arrhythmias.
- INR is monitored closely if the patient is taking warfarin; the prescribing clinician manages any warfarin dose adjustment based on the results.
- Digoxin levels should be followed if used concurrently.
- Watch for signs of pulmonary toxicity (new or worsening cough, dyspnea) – this can occur at any time.
- Advise patients to avoid excessive sun exposure and to report any skin discoloration or visual changes.
Storage
No specific storage instructions were captured in this research pass. Refer to the manufacturer's package insert for the specific product you are using.
Study the drug class: Class III antiarrhythmics
Professional information
Clinician-facing context only. Use the current local indication, dosing table, and monitoring protocols from official labeling. Amiodarone has significant toxicity and drug interaction potential, requiring specialist oversight.
United States
Indication: Recurrent ventricular fibrillation or hemodynamically unstable ventricular tachycardia
Dose summary: Loading: 800–1600 mg/day for 1–3 weeks; Transition: 600–800 mg/day for 1 month; Maintenance: 400 mg/day. Continuous ECG monitoring required during initiation. Whether the loading dose is given in divided amounts was not established in the sources reviewed.
Renal context: No specific renal-impairment dosing information was captured in this research pass. (1)
United Kingdom
Indication: Severe rhythm disorders not responding to other therapies (including atrial flutter/fibrillation, paroxysmal tachycardias, WPW syndrome)
Dose summary: Loading: 200 mg three times daily for 1 week, then 200 mg twice daily for 1 week; Maintenance: 200 mg daily (or less according to response).
Renal context: No specific renal-impairment dosing information was captured in this research pass. (2)
Hepatic guidance
Amiodarone is extensively metabolized in the liver. Use in hepatic impairment requires specialist judgment; no specific dose-adjustment recommendations were captured in this research pass.
Overdose note
The parent drug's long elimination half-life (mean 53 days) is documented pharmacokinetic information but was not linked to a specific overdose-management instruction in the sources reviewed. (1) (2)
Frequently asked questions
Why do I need so many tests while taking amiodarone?
Amiodarone can affect your lungs, liver, thyroid, eyes, and heart rhythm. Regular testing helps catch any problems early. Lung function tests, liver enzymes, thyroid hormones, and eye exams are done at set intervals to keep you safe. (1) (2)
Can amiodarone affect my thyroid?
Yes. Amiodarone can cause both hypothyroidism (underactive thyroid) and hyperthyroidism (overactive thyroid). Your thyroid function will be checked before starting and periodically during treatment (every 6 months per UK guidance; baseline and periodic testing per US labeling). Report any symptoms like fatigue, weight changes, palpitations, or heat/cold intolerance. (1) (2)
Can I breastfeed while taking amiodarone?
Amiodarone passes into breast milk in significant amounts, which could harm a nursing infant. In the UK, breastfeeding is contraindicated; in the US, it is not recommended while taking amiodarone. Discuss feeding and treatment options with your clinician. (1) (2)
What should I do if I miss a dose?
No specific missed-dose instructions are available from the reviewed sources. Contact your prescribing clinician for individual advice.
What is the mechanism of action of amiodarone?
Amiodarone is a class III antiarrhythmic that prolongs the cardiac action potential and refractory period by blocking potassium channels; it also has class I (sodium-channel block) effects. Not established from the sources reviewed: specific beta-adrenergic-block (class II) and calcium-channel-block (class IV) mechanistic details were not separately established in the sources reviewed for this page, beyond the general classification of amiodarone as having properties of all four Vaughan-Williams classes. Oral bioavailability is approximately 50%, with peak plasma concentrations at 3–7 hours. The parent drug has a mean elimination half-life of 53 days (range 26–107 days); the active metabolite desethylamiodarone has a half-life of about 61 days. Steady state without loading doses may take 130–535 days. Volume of distribution is about 60 L/kg, indicating extensive tissue accumulation. Metabolism is hepatic via CYP3A and CYP2C8; excretion is primarily biliary with negligible renal elimination. (1) (2)
References
- AMIODARONE HYDROCHLORIDE tablet — prescribing informationU.S. National Library of Medicine, DailyMed · United States · accessed 2026-08-05 · source 1
- Amiodarone Hydrochloride 200mg Tablets — Summary of Product Characteristicselectronic Medicines Compendium (UK) · United Kingdom · accessed 2026-08-05 · source 2
- AMIODARONE HYDROCHLORIDE TABLET [REMEDYREPACK INC.] — US prescribing information (DailyMed SPL)U.S. National Library of Medicine (DailyMed) · US · accessed 2026-08-14 · source 3
- Amiodarone — patient drug information (MedlinePlus)U.S. National Library of Medicine (MedlinePlus) · US · accessed 2026-08-14 · source 4
- Pacerone — FDA approval record (Drugs@FDA ANDA075135)U.S. Food and Drug Administration · US · accessed 2026-08-14 · source 5
- amiodarone — RxNorm normalized drug concept (RXCUI 203114)U.S. National Library of Medicine (RxNorm) · US · accessed 2026-08-14 · source 6
Brand names by country
Single-ingredient amiodarone names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.
Priority countries
United States
- Pacerone100 mg, 200 mg, 400 mg · bryant ranch prepack
- NEXTERONE (AMIODARONE HCI)1.8 mg/mL, 1.5 mg/mL · hf acquisition co llc, dba healthfirst
- Nexterone1.5 mg/mL, 1.8 mg/mL · baxter healthcare corporation
- AMIODARONE HCI50 mg/mL · hf acquisition co llc, dba healthfirst