Digoxin: Uses, Dosage & Side Effects
Cardiac glycoside for heart failure and atrial fibrillation – intravenous solution for injection
Quick facts about Digoxin
Key takeaways about Digoxin
- Narrow therapeutic index: Digoxin requires regular plasma concentration monitoring; the target is 0.5–1.0 ng/ml (0.6–1.3 nmol/L). Toxicity can be life-threatening
- Strengthens the heart: Digoxin increases the force of heart contractions and slows the heart rate, making it useful for both heart failure and atrial fibrillation
- Kidney function matters: Digoxin is primarily eliminated by the kidneys. Dose must be reduced in patients with impaired renal function to prevent accumulation and toxicity
- Electrolyte balance is critical: Low potassium (hypokalaemia), high calcium (hypercalcaemia), or low magnesium (hypomagnesaemia) significantly increase the risk of digoxin toxicity
- Many drug interactions: Amiodarone, verapamil, quinidine, and diuretics are among the drugs that can dangerously alter digoxin levels or increase toxicity risk
What Is Digoxin and What Is It Used For?
Digoxin is a cardiac glycoside medication used to treat heart failure, atrial fibrillation, and atrial flutter. It works by strengthening the heart’s contractions (positive inotropic effect) and slowing the heart rate through increased vagal tone, improving cardiac output and reducing symptoms such as breathlessness and fluid retention.
Digoxin belongs to a class of medications known as cardiac glycosides, which are derived from the foxglove plant (Digitalis lanata). The use of digitalis preparations in medicine dates back to 1785, when the English physician William Withering first described the use of foxglove extract for “dropsy” (oedema caused by heart failure). Today, digoxin remains on the WHO Model List of Essential Medicines and continues to play an important role in cardiovascular therapy, despite the development of many newer heart failure medications.
Digoxin exerts its therapeutic effects through two principal mechanisms. First, it inhibits the sodium-potassium ATPase (Na+/K+-ATPase) pump in cardiac muscle cells. This enzyme is responsible for maintaining the electrochemical gradient across cell membranes. By blocking this pump, digoxin causes an accumulation of intracellular sodium, which in turn increases intracellular calcium via the sodium-calcium exchanger. The elevated calcium enhances the contractile force of the heart muscle – a property known as the positive inotropic effect. This means the heart pumps more efficiently with each beat, improving cardiac output and reducing symptoms of heart failure.
Second, digoxin has important effects on the cardiac conduction system. It increases parasympathetic (vagal) tone, which slows conduction through the atrioventricular (AV) node and reduces the heart rate – the negative chronotropic effect. This property makes digoxin particularly valuable for controlling the ventricular rate in patients with atrial fibrillation or atrial flutter, where the heart’s upper chambers beat irregularly and often too quickly.
The intravenous formulation of digoxin is particularly useful in acute clinical settings where rapid onset of action is required. When given intravenously, digoxin begins to take effect within 5–30 minutes, with peak effects occurring at 1–5 hours. This is significantly faster than the oral formulation, which has an onset of 0.5–2 hours and peak effect at 2–6 hours.
The primary clinical indications for digoxin include:
- Heart failure (HF): Digoxin improves symptoms and exercise tolerance in patients with heart failure with reduced ejection fraction (HFrEF), particularly when symptoms persist despite treatment with ACE inhibitors, beta-blockers, and diuretics. The landmark DIG trial (1997) demonstrated that digoxin reduces hospitalisations for heart failure, although it does not reduce overall mortality
- Atrial fibrillation (AF): Digoxin is used for ventricular rate control in atrial fibrillation, particularly at rest. It is most effective in sedentary patients and those with concurrent heart failure, as it does not control heart rate well during exercise
- Atrial flutter (AFL): Similar to its use in atrial fibrillation, digoxin can slow the ventricular response rate in atrial flutter by increasing AV nodal refractoriness
Current guidelines (ESC 2023, AHA/ACC 2022) position digoxin as a second- or third-line agent for heart failure, recommended when symptoms persist despite optimal therapy with ACE inhibitors/ARBs, beta-blockers, mineralocorticoid receptor antagonists, and SGLT2 inhibitors. For rate control in atrial fibrillation, beta-blockers or calcium channel blockers are generally preferred first-line, with digoxin added when rate control remains inadequate or in patients with heart failure.
In heart failure, digoxin has a unique role because it is one of the few positive inotropic agents that can be given long-term without increasing mortality (unlike catecholamines such as dobutamine). Post-hoc analyses of the DIG trial have suggested that lower serum digoxin concentrations (0.5–0.9 ng/ml) are associated with a reduction in all-cause mortality, while higher levels (>1.0 ng/ml) may increase the risk of death. This finding has led to a paradigm shift in digoxin dosing, with current practice favouring lower target concentrations than were traditionally used.
What Should You Know Before Taking Digoxin?
Digoxin has important contraindications and requires careful assessment before use. Certain heart rhythm disorders, electrolyte imbalances, and kidney impairment significantly affect its safety. Your doctor will evaluate your kidney function, electrolyte levels, and cardiac status before initiating treatment.
Contraindications
Digoxin must not be used in patients with the following conditions:
- Hypersensitivity to digoxin or any other cardiac glycoside, or to any excipient in the formulation
- Ventricular tachycardia or ventricular fibrillation: Digoxin can worsen these life-threatening arrhythmias
- Hypertrophic obstructive cardiomyopathy (HOCM): Unless concurrent atrial fibrillation is present, digoxin may worsen outflow obstruction
- Second- or third-degree heart block without a permanent pacemaker, as digoxin further slows AV conduction
- Severe sinus node disease (sick sinus syndrome) without a pacemaker
- Accessory pathway-mediated tachycardia (e.g., Wolff-Parkinson-White syndrome) – digoxin can enhance conduction through the accessory pathway, potentially triggering ventricular fibrillation
- Constrictive pericarditis: Digoxin is ineffective and may be hazardous in this condition
Warnings and Precautions
Inform your doctor about your complete medical history before receiving digoxin. The following conditions require particular caution and may necessitate dose adjustments or enhanced monitoring:
- Impaired kidney function: Digoxin is primarily excreted by the kidneys. Reduced renal clearance leads to drug accumulation, significantly increasing the risk of toxicity. Dose reduction is essential in patients with any degree of renal impairment, and regular plasma level monitoring is strongly recommended
- Hypothyroidism: Patients with underactive thyroid glands are more sensitive to digoxin and generally require lower doses. Conversely, hyperthyroidism increases digoxin clearance and may require higher doses
- Hypokalaemia (low potassium): This is one of the most important risk factors for digoxin toxicity. Low potassium levels increase the binding of digoxin to the Na+/K+-ATPase pump, amplifying its effects. Potassium levels must be monitored regularly, especially in patients taking diuretics
- Hypercalcaemia (high calcium): Elevated calcium potentiates the effects of digoxin on the heart and increases the risk of arrhythmias
- Hypomagnesaemia (low magnesium): Magnesium depletion increases susceptibility to digoxin toxicity, similar to hypokalaemia
- Severe cardiac disease: Patients with acute myocarditis, amyloid heart disease, or severe cardiomyopathy may be unusually sensitive to digoxin
- Hypoxia: Reduced oxygen levels in body tissues increase the risk of cardiac arrhythmias during digoxin therapy
- Elderly patients: Age-related decline in kidney function means elderly patients typically require lower doses and more frequent monitoring
Observational studies have suggested a possible increased risk of mortality in patients with atrial fibrillation who are treated with digoxin long-term. While causality has not been definitively established and confounding factors may play a role, this finding has led to more cautious use. Current guidelines recommend considering digoxin for rate control primarily when other agents (beta-blockers, calcium channel blockers) are insufficient or contraindicated.
Pregnancy and Breastfeeding
Digoxin crosses the placenta and reaches the foetus, but no known teratogenic effects (birth defects) have been documented in human pregnancies. Digoxin has been used during pregnancy when clinically necessary, including for the treatment of foetal supraventricular tachycardia. Nevertheless, as with all medications during pregnancy, digoxin should only be used when the expected benefit outweighs the potential risk, and under close medical supervision.
Digoxin is excreted in breast milk in small amounts. At therapeutic maternal doses, the amount reaching the infant through breast milk is considered clinically insignificant and unlikely to cause adverse effects. Breastfeeding is generally considered compatible with digoxin use, but the infant should be monitored for any unusual symptoms.
Driving and operating machinery: Digoxin may cause side effects such as fatigue, confusion, and visual disturbances. If you experience any of these symptoms, do not drive or operate machinery. You are responsible for assessing your own fitness to drive, taking into account the effects of your medication.
The intravenous solution of digoxin contains ethanol (20% v/v) and propylene glycol (400 mg/ml). These excipients may be harmful to patients with alcoholism, liver disease, or epilepsy. In children under 5 years, or in pregnant and breastfeeding women, the healthcare provider should consider the cumulative effects of ethanol and propylene glycol, especially if the patient is receiving other medications containing these substances. Additional monitoring may be warranted in patients with impaired liver or kidney function.
How Does Digoxin Interact with Other Drugs?
Digoxin interacts with a large number of medications. Many drugs can increase digoxin blood levels, potentially causing toxicity, while others can reduce its effectiveness. Drugs that cause electrolyte disturbances (particularly low potassium) dramatically increase the risk of digoxin toxicity even without changing blood levels.
Digoxin interactions fall into three main categories: drugs that increase digoxin plasma levels (by reducing its renal clearance, increasing absorption, or reducing volume of distribution), drugs that decrease digoxin levels (by reducing absorption or increasing elimination), and drugs that increase the pharmacological sensitivity to digoxin (particularly those causing electrolyte disturbances). Due to digoxin’s narrow therapeutic index, even small changes in plasma levels or myocardial sensitivity can have clinically significant consequences.
Always inform your doctor, pharmacist, or nurse about all medications you are taking – including over-the-counter medicines, herbal remedies, and dietary supplements – before starting digoxin. The following tables summarise the most clinically important interactions.
Major Interactions (Avoid or Use with Extreme Caution)
| Drug / Class | Effect on Digoxin | Clinical Significance |
|---|---|---|
| Amiodarone | Increases digoxin levels by 70–100% | Reduce digoxin dose by 50% when starting amiodarone. Monitor levels closely. Effect persists for weeks after stopping |
| Verapamil | Increases digoxin levels by 50–75% | Reduce digoxin dose by 33–50%. Both drugs also slow AV conduction, increasing risk of bradycardia and heart block |
| Quinidine | Doubles digoxin levels | Halve the digoxin dose when quinidine is started. Displaces digoxin from tissue binding sites and reduces renal clearance |
| Dronedarone | Increases digoxin levels by 150% | Reduce digoxin dose by 50% or more. Monitor plasma levels and ECG for signs of toxicity |
| Ciclosporin | Increases digoxin levels | Reduces renal clearance of digoxin. Monitor levels and adjust dose accordingly |
| Loop diuretics (furosemide, bumetanide) | Increases toxicity risk via hypokalaemia | Monitor potassium and magnesium regularly. Consider potassium supplementation or potassium-sparing diuretic |
| Thiazide diuretics (hydrochlorothiazide) | Increases toxicity risk via hypokalaemia | Same electrolyte monitoring as loop diuretics. Ensure potassium remains within normal range |
Moderate Interactions (Use with Caution)
| Drug / Substance | Effect on Digoxin | Recommendation |
|---|---|---|
| Macrolide antibiotics (erythromycin, clarithromycin) | Increases digoxin levels by 40–100% | Inhibit gut bacteria that metabolise digoxin (Eubacterium lentum). Monitor levels during and after antibiotic course |
| Tetracyclines | May increase digoxin levels | Similar mechanism to macrolides via gut flora disruption. Monitor plasma levels |
| Spironolactone | May increase digoxin levels by 25% | Reduces renal clearance of digoxin. Can also interfere with digoxin immunoassays. Use monitored carefully |
| Proton pump inhibitors (omeprazole) | May slightly increase digoxin absorption | Minor effect. Monitor if starting or stopping a PPI in a patient on stable digoxin |
| Antacids, kaolin, cholestyramine | Reduces digoxin absorption | Separate administration by at least 2 hours. Less relevant for IV digoxin |
| Rifampicin | Reduces digoxin levels by 30–50% | Induces intestinal P-glycoprotein. Higher digoxin doses may be needed. Monitor levels |
| St John’s Wort | Reduces digoxin levels by up to 25% | Induces P-glycoprotein. Avoid combination or monitor levels closely if used |
| Enzalutamide | May interfere with digoxin assays | Can cause falsely elevated or reduced digoxin test results. Inform laboratory of concurrent use |
Beta-blockers and non-dihydropyridine calcium channel blockers (verapamil, diltiazem) have additive effects on AV nodal conduction when used with digoxin. While these combinations can be therapeutically useful for rate control, they increase the risk of profound bradycardia and heart block. Patients receiving these combinations require close monitoring of heart rate and rhythm.
Intravenous calcium should be used with extreme caution (or avoided) in patients receiving digoxin, as the combination can precipitate serious arrhythmias. Conversely, rapid correction of hypokalaemia with IV potassium must be done carefully, as both hypokalaemia and hyperkalaemia can cause arrhythmias in the presence of digoxin.
What Is the Correct Dosage of Digoxin?
Digoxin dosing is highly individualised based on kidney function, age, weight, and clinical response. The intravenous formulation is used when oral administration is not feasible or when rapid digitalisation is required. Plasma concentration monitoring is essential, with an initial target below 1.0 ng/ml (1.3 nmol/L).
Digoxin has one of the narrowest therapeutic indices of any commonly used medication. The difference between a therapeutic dose and a toxic dose is remarkably small, which is why plasma concentration monitoring is so important. The concept of “digitalisation” refers to the process of achieving and maintaining therapeutic digoxin levels, which can be accomplished either rapidly (for acute situations) or slowly (for stable chronic conditions).
Adults
Slow Digitalisation (Non-Acute Situations)
The calculated maintenance dose is given from the outset: 0.1–0.35 mg (0.4–1.4 ml) intravenously once daily, either as a single dose or divided into two doses. When using this approach, therapeutic steady-state concentrations are achieved in approximately 5–10 days (roughly 5 half-lives). This is the preferred method in most clinical situations as it carries less risk of toxicity.
Rapid Digitalisation (Emergency Situations)
Rapid digitalisation should only be performed under continuous medical supervision with ECG monitoring. For a 70 kg adult without obesity:
- Initial dose: 0.5–0.75 mg IV (2–3 ml), administered slowly at a rate not exceeding 0.1 mg/min
- Subsequent doses: 0.25 mg IV (1 ml) every 3 hours as needed until adequate effect is achieved
- Maximum first-day dose: Should not exceed 1.5 mg IV (6 ml) in total
- After 24 hours: Switch to maintenance dosing
The solution should be administered slowly intravenously (at 0.1 mg/min), optionally after dilution with 0.9% sodium chloride solution. Digoxin injection should not be added to intravenous infusion bags.
Intramuscular administration of digoxin should be avoided because it causes significant pain at the injection site, can lead to tissue necrosis, and results in slower and more unpredictable absorption compared with the intravenous route.
Children
Paediatric Dosing (Under Specialist Supervision Only)
Digoxin dosing in children varies considerably with age, as the ability to eliminate digoxin changes significantly during the first six months of life. All paediatric dosing should be calculated on a per-kilogram basis and supervised by a specialist. The injection solution can be diluted with 0.9% sodium chloride if the dose volume is less than 0.5 ml.
| Age Group | Rapid Digitalisation (IV) | Maintenance Dose (IV/day) |
|---|---|---|
| Neonate (full-term) | 0.020 mg/kg (0.08 ml/kg) | 0.007 mg/kg (0.028 ml/kg) |
| Premature infant | Substantially reduced dose | Substantially reduced dose |
| 6 months | 0.030 mg/kg (0.12 ml/kg) | 0.010–0.020 mg/kg (0.04–0.08 ml/kg) |
| 2 years and older | 0.015 mg/kg (0.06 ml/kg) | 0.007 mg/kg (0.028 ml/kg) |
Maintenance treatment in children is often given every 12 hours and should commence 12 hours after the rapid digitalisation dose. Dose requirements per kilogram of body weight gradually decrease after the first year of life, approaching adult values as the child grows older.
Elderly Patients
Elderly Dosing Considerations
Elderly patients generally require lower doses of digoxin due to age-related decline in renal function, reduced lean body mass, and increased sensitivity to the drug. Even in patients with serum creatinine values that appear normal, actual glomerular filtration rate may be significantly reduced. Estimated GFR (eGFR) should guide dosing rather than serum creatinine alone. More frequent plasma concentration monitoring is recommended in this population.
Dose Adjustments in Special Populations
Several factors require specific dose adjustments:
- Renal impairment: Digoxin clearance correlates directly with creatinine clearance. In significant renal impairment (eGFR <30 ml/min), the dose should be reduced by 50% or more, and plasma levels should be monitored frequently
- Obesity: Digoxin distributes into lean body mass, not adipose tissue. In obese patients, dosing should be based on ideal body weight, not actual body weight, to avoid overdosing
- Hypothyroidism: Patients with hypothyroidism are more sensitive to digoxin and typically require lower doses
- Switching from another cardiac glycoside: When switching from digitoxin to digoxin, a reduced dose of digoxin should be used initially (e.g., half the calculated maintenance dose for the first week) to avoid temporary over-digitalisation, due to the long half-life of digitoxin
Therapeutic Drug Monitoring
Plasma digoxin concentration monitoring is a cornerstone of safe digoxin therapy. Key points include:
- Target concentration: Current evidence supports a target of 0.5–1.0 ng/ml (0.6–1.3 nmol/L) for heart failure. For rate control in atrial fibrillation, levels up to 2.0 ng/ml may be tolerated, though lower levels are preferred
- Timing of blood sampling: Blood should be drawn at least 6 hours after the last dose (ideally 8–12 hours) to allow for complete distribution. Samples taken too early may give falsely elevated results
- When to measure: At least once after achieving steady state (5–10 days), and whenever toxicity is suspected, renal function changes, interacting drugs are started or stopped, or clinical status changes
Missed Dose
In the hospital setting where intravenous digoxin is administered, missed doses are managed by the medical team. If a scheduled dose is missed, it should generally be given as soon as possible unless the next dose is due within a few hours. A double dose should never be given to compensate for a missed dose.
Overdose
Digoxin overdose can be life-threatening and requires immediate medical attention. Symptoms of overdose include:
- Nausea, vomiting, loss of appetite, and diarrhoea
- Severe headache, fatigue, and confusion
- Reduced consciousness and hallucinations
- Visual disturbances: blurred vision, yellow or green colour vision changes (xanthopsia – classically described as seeing a yellow halo around lights)
- Involuntary rapid body movements
- Seizures (in severe cases)
- Cardiac arrhythmias: any type, but classically bidirectional ventricular tachycardia, atrial tachycardia with block, or accelerated junctional rhythm
If digoxin overdose is suspected, treatment should include immediate cessation of digoxin, continuous ECG monitoring, and correction of any electrolyte abnormalities (particularly hypokalaemia and hypomagnesaemia). For severe or life-threatening toxicity, the specific antidote is digoxin-specific antibody fragments (digoxin immune Fab), marketed as DigiFab or Digibind. These antibody fragments bind to circulating digoxin, rapidly neutralising its toxic effects. Indications for the antidote include haemodynamically unstable arrhythmias, potassium levels above 5.5 mmol/L in the context of digoxin toxicity, or confirmed massive ingestion.
What Are the Side Effects of Digoxin?
Digoxin side effects occur primarily when plasma levels are too high or when electrolyte imbalances are present. Common side effects include loss of appetite, nausea, fatigue, headache, and cardiac rhythm disturbances. Visual disturbances (blurred vision, yellow-green colour changes) are a classic hallmark of digoxin toxicity.
Like all medicines, digoxin can cause side effects, although not everyone experiences them. The risk of adverse effects is closely related to plasma concentration – most side effects occur when digoxin levels exceed the therapeutic range or when predisposing factors such as electrolyte disturbances are present. Understanding these side effects and recognising the early signs of toxicity is critical for safe treatment, as toxicity can rapidly progress from mild gastrointestinal symptoms to life-threatening arrhythmias.
Common (affects up to 1 in 10 patients)
- Loss of appetite (anorexia)
- Nausea and vomiting
- Diarrhoea
- Fatigue and weakness
- Headache
- Cardiac arrhythmias (irregular heart rhythm)
- Disturbances in the cardiac conduction system
Uncommon (affects up to 1 in 100 patients)
- Confusion and disorientation
- Visual disturbances: blurred vision, yellow-green colour vision changes (xanthopsia)
- Dizziness
- Depression
Rare (frequency not known)
- Gynaecomastia (breast enlargement in men) – associated with long-term use due to the oestrogen-like structure of digoxin
- Skin rash
- Thrombocytopenia (low platelet count)
- Hallucinations
- Seizures (with severe toxicity)
The gastrointestinal symptoms (nausea, vomiting, anorexia) are often the earliest signs of digoxin toxicity and should prompt immediate plasma level measurement. Visual disturbances, particularly the characteristic yellow-green discolouration of vision, are a well-known but less common sign of toxicity. Notably, the famous painter Vincent van Gogh, who was treated with digitalis, may have experienced xanthopsia – some art historians have suggested this could explain the prominent yellow tones in his later paintings.
Cardiac side effects are the most dangerous and can include virtually any type of arrhythmia. Classic digoxin-toxic arrhythmias include atrial tachycardia with AV block, bidirectional ventricular tachycardia, accelerated junctional rhythm, and frequent premature ventricular complexes (PVCs). If you notice a sudden change in your heart rate or rhythm, or experience palpitations, dizziness, or fainting, seek medical attention immediately.
It is important to report suspected side effects after a medicine has been authorised. This allows continued monitoring of the benefit-risk balance of the medicine. Healthcare professionals and patients are encouraged to report suspected adverse reactions to their national medicines regulatory authority (e.g., EMA in Europe, FDA in the United States, MHRA in the United Kingdom).
How Should You Store Digoxin?
Digoxin injection solution should be stored in the original carton to protect from light. Keep at room temperature and check the expiry date before use. As a hospital medication, storage is typically managed by the pharmacy or nursing staff.
Proper storage of digoxin is essential to maintain its potency and safety. The following guidelines apply to the injectable formulation:
- Keep out of reach of children: Store all medications where children cannot access them
- Store in the original carton: The outer packaging protects the solution from light, which can degrade the active ingredient
- Temperature: Store at room temperature (below 25°C / 77°F) unless otherwise specified
- Expiry date: Do not use after the expiry date printed on the packaging. The expiry date refers to the last day of the stated month
- Inspect before use: The solution should be clear and colourless. Do not use if the solution appears cloudy, discoloured, or contains visible particles
- Single use: Each ampoule is for single use only. Any unused solution should be discarded according to local pharmaceutical waste guidelines
In a hospital setting, the pharmacy department typically manages the storage and distribution of injectable digoxin, ensuring compliance with all storage requirements and temperature monitoring standards.
What Does Digoxin Contain?
Each 1 ml of digoxin injection contains 0.25 mg of the active substance digoxin. The solution also contains ethanol, propylene glycol, citric acid (anhydrous), disodium phosphate dihydrate, and water for injections.
Understanding the full composition of a medication is important for identifying potential allergies or sensitivities to both active and inactive ingredients.
Active Ingredient
Digoxin 0.25 mg/ml – a cardiac glycoside that strengthens the heart’s contractions and controls heart rate.
Inactive Ingredients (Excipients)
- Ethanol (alcohol): 20% v/v – used as a co-solvent to dissolve digoxin. A 1 ml dose contains up to 100 mg of ethanol, equivalent to approximately 2.5 ml of beer or 1 ml of wine
- Propylene glycol: 400 mg per 1 ml – used as a co-solvent and stabiliser
- Citric acid (anhydrous): Used to adjust the pH of the solution
- Disodium phosphate dihydrate: Used as a buffering agent
- Water for injections: Sterile water used as the base solvent
The solution is supplied in clear glass ampoules of 1 ml. The packaging contains 10 ampoules per box. The solution is clear and colourless.
The ethanol content may be harmful to patients with alcoholism, and the content should be considered in pregnant or breastfeeding women, children, and patients with liver disease or epilepsy. The propylene glycol content (approximately 35 mg/kg/day for adults at a 1 ml dose) is within safe limits for most patients but may require additional monitoring in patients with impaired liver or kidney function and in children under 5 years of age.
Frequently Asked Questions About Digoxin
Digoxin is a cardiac glycoside medication used to treat heart failure, atrial fibrillation, and atrial flutter. It works by strengthening the heart’s contractions (positive inotropic effect) and slowing the heart rate by increasing vagal tone and reducing conduction through the AV node. In heart failure, digoxin improves symptoms and reduces hospitalisations. In atrial fibrillation and flutter, it helps control the ventricular rate, particularly at rest.
Digoxin toxicity can present with gastrointestinal symptoms (nausea, vomiting, loss of appetite, diarrhoea), neurological symptoms (fatigue, confusion, dizziness, headache, hallucinations), visual disturbances (blurred vision, yellow-green colour changes known as xanthopsia), and cardiac arrhythmias (which can be any type but classically include atrial tachycardia with block and bidirectional ventricular tachycardia). Toxicity is more likely when plasma levels exceed 2 ng/ml or when electrolyte imbalances (low potassium, low magnesium, high calcium) are present. If you suspect toxicity, seek immediate medical attention.
Digoxin plasma levels should be checked after achieving steady state (typically 5–10 days after starting or changing the dose), and whenever toxicity is suspected, renal function changes significantly, interacting drugs are started or stopped, or clinical status deteriorates. Blood should be drawn at least 6 hours (ideally 8–12 hours) after the last dose. The target level is generally 0.5–1.0 ng/ml (0.6–1.3 nmol/L) for heart failure, with levels kept below 2.0 ng/ml for rate control in atrial fibrillation.
Digoxin crosses the placenta but no known teratogenic effects have been documented. It has been used during pregnancy when clinically necessary and is considered one of the safer cardiac medications in pregnancy. Digoxin passes into breast milk in small amounts, but at therapeutic maternal doses, the amount reaching the infant is considered clinically insignificant. Breastfeeding is generally compatible with digoxin use. However, the injectable formulation contains ethanol and propylene glycol, which require additional consideration during pregnancy and breastfeeding. Always discuss with your doctor before using any medication during pregnancy or while breastfeeding.
Digoxin and digitoxin are both cardiac glycosides but differ significantly in their pharmacological properties. Digoxin is primarily eliminated by the kidneys and has a half-life of 36–48 hours, while digitoxin is metabolised by the liver and has a much longer half-life of 4–6 days. Digoxin requires dose reduction in renal impairment, whereas digitoxin may be preferred in patients with kidney disease. Digoxin is far more widely used globally and is the standard cardiac glycoside in current clinical practice. When switching from digitoxin to digoxin, a reduced initial dose of digoxin is needed to avoid temporary over-digitalisation.
Yes. The specific antidote for severe digoxin toxicity is digoxin-specific antibody fragments (digoxin immune Fab), available as DigiFab or Digibind. These antibody fragments bind to circulating digoxin molecules, neutralising their toxic effects within 30–60 minutes. The antidote is used for life-threatening arrhythmias, hyperkalaemia exceeding 5.5 mmol/L in the context of digoxin toxicity, or confirmed massive ingestion. Supportive treatment includes correction of electrolyte imbalances, atropine for symptomatic bradycardia, and temporary cardiac pacing if needed. Haemodialysis is not effective for removing digoxin due to its large volume of distribution.
Potassium and digoxin compete for the same binding site on the Na+/K+-ATPase pump. When potassium levels are low (hypokalaemia), more digoxin binds to the pump, amplifying its effect and increasing the risk of toxicity – even at normal plasma digoxin levels. This is particularly important because many heart failure patients take diuretics (such as furosemide or hydrochlorothiazide), which can deplete potassium. Conversely, high potassium can also cause arrhythmias in patients on digoxin. Potassium levels should be maintained between 4.0–5.0 mmol/L for patients receiving digoxin therapy.
References
All medical information on this page is based on peer-reviewed research and international clinical guidelines:
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- Heidenreich PA, Bozkurt B, Aguilar D, et al. 2022 AHA/ACC/HFSA Guideline for the Management of Heart Failure. J Am Coll Cardiol. 2022;79(17):e263–e421. doi:10.1016/j.jacc.2021.12.012
- The Digitalis Investigation Group. The effect of digoxin on mortality and morbidity in patients with heart failure. N Engl J Med. 1997;336(8):525–533. doi:10.1056/NEJM199702203360801
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- Hindricks G, Potpara T, Dagres N, et al. 2020 ESC Guidelines for the diagnosis and management of atrial fibrillation. Eur Heart J. 2021;42(5):373–498. doi:10.1093/eurheartj/ehaa612
- British National Formulary (BNF). Digoxin. National Institute for Health and Care Excellence (NICE). Last updated 2025.
- World Health Organization. WHO Model List of Essential Medicines – 23rd List (2023). Geneva: WHO; 2023.
- European Medicines Agency (EMA). Digoxin – Summary of Product Characteristics. EMA; 2024.
- Vamos M, Erath JW, Hohnloser SH. Digoxin-associated mortality: a systematic review and meta-analysis of the literature. Eur Heart J. 2015;36(28):1831–1838. doi:10.1093/eurheartj/ehv143
- Ziff OJ, Lane DA, Samra M, et al. Safety and efficacy of digoxin: systematic review and meta-analysis of observational and controlled trial data. BMJ. 2015;351:h4451. doi:10.1136/bmj.h4451
Editorial Team
This article has been written and reviewed by the iMedic Medical Editorial Team, a panel of licensed specialist physicians with expertise in clinical pharmacology, cardiology, and internal medicine.
Written by physicians specialising in clinical pharmacology and cardiology, following international guidelines (ESC, AHA/ACC, WHO, BNF).
Reviewed by the iMedic Medical Review Board. All claims verified against peer-reviewed sources with Evidence Level 1A.
GRADE evidence framework applied. Based on systematic reviews, randomised controlled trials, and international clinical guidelines.
No commercial funding. No pharmaceutical sponsorship. Independent medical editorial content reviewed according to international standards.