Digoxin — NZ Medication Guide
📋 Reviewed by a Registered Pharmacist NZ — This information is for general educational purposes only and does not replace professional medical advice. Always consult your doctor or pharmacist before starting, stopping, or changing any medication.
What is Digoxin?
Digoxin is a cardiac glycoside derived from the foxglove plant (Digitalis lanata), used for heart failure and rate control in atrial fibrillation. This medication is commonly prescribed in New Zealand and is funded by Pharmac for heart failure and atrial fibrillation.
What is Digoxin Used For?
Digoxin is used to slow the ventricular rate in atrial fibrillation and to improve symptoms in heart failure with reduced ejection fraction, particularly when symptoms persist despite other therapy.
How Does Digoxin Work?
Digoxin inhibits the sodium-potassium ATPase pump in cardiac muscle cells, increasing intracellular calcium and enhancing myocardial contractility (positive inotrope). It also activates the vagal nerve, slowing conduction through the atrioventricular node and reducing ventricular rate in atrial fibrillation.
How to Take Digoxin
Usually taken once daily, at the same time each day. Digoxin has a narrow therapeutic index — levels must be monitored regularly via blood tests. Do not skip doses or double-dose if missed. Avoid taking with high-fibre meals which can reduce absorption.
Common Side Effects of Digoxin
- Nausea and vomiting
- Loss of appetite
- Fatigue
- Headache
- Visual disturbances (blurred or yellow-green vision — a warning sign of toxicity)
Serious Side Effects — Seek Medical Attention
Contact your doctor or call 111 immediately if you experience any of the following:
- Digoxin toxicity: severe nausea, vomiting, confusion, visual changes, dangerous arrhythmias
- Very slow or irregular heart rate
- Low potassium levels (which increase toxicity risk)
- Fainting
Drug Interactions
Digoxin may interact with other medicines. Always inform your doctor and pharmacist of all medications, supplements, and herbal products you are taking. Key interactions include:
- Amiodarone and verapamil (markedly increase digoxin levels — dose reduction required)
- Diuretics causing hypokalaemia (increase toxicity risk)
- Macrolide antibiotics (erythromycin, clarithromycin — increase digoxin levels)
- Rifampicin (reduces digoxin levels)
- St John’s Wort (reduces levels)
New Zealand Prescribing Information
Digoxin is funded by Pharmac and available as 62.5 microgram and 125 microgram tablets and as an injection. Due to its narrow therapeutic index and the availability of safer alternatives, digoxin is now mainly used when patients remain symptomatic despite optimal beta-blocker and diuretic therapy. Regular serum digoxin and electrolyte monitoring is essential.
Frequently Asked Questions
How do I know if I have digoxin toxicity?
Signs of toxicity include nausea, vomiting, loss of appetite, confusion, and visual disturbances (objects appearing yellow-green or having halos). If you experience these, seek urgent medical attention and contact your doctor.
Why do I need blood tests while on digoxin?
Digoxin has a narrow therapeutic index — the difference between a helpful dose and a toxic dose is small. Blood tests check your digoxin level and electrolytes (especially potassium), which affect digoxin’s safety.
⚠️ Disclaimer: This page is for educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your doctor or a qualified health provider with any questions you may have regarding a medical condition or medication. In New Zealand, medication availability and funding may vary — check with Pharmac or your pharmacist for the most current information.
Reviewed by a Registered Pharmacist NZ
References & Further Information
The following New Zealand and international resources were used to inform this page: