Digoxin

Key facts

• Digoxin is a cardiac glycoside, originally derived from the foxglove plant, that strengthens each heartbeat and slows the heart rate. It treats heart failure and atrial fibrillation.
• You take it once daily, usually at the same time each day; the effect builds over several days as the drug reaches a steady level in your blood.
• Digoxin has a narrow therapeutic index: the effective dose and the toxic dose are close together. Amiodarone, verapamil, and low blood potassium are common triggers that push a normal dose into the toxic range.
• Seek urgent care for nausea, visual halos or blurred and yellow-tinged vision, and a pulse that turns very slow or irregular. These are signs of digoxin toxicity.

What digoxin treats

Digoxin treats heart failure, where the heart cannot pump enough blood to meet the body's needs, and it controls the heart rate in atrial fibrillation and atrial flutter. It eases breathlessness, leg swelling, and fatigue linked to a weak or fast-beating heart. It does not treat high blood pressure on its own and is no longer a first-choice drug for most people with heart failure.

How digoxin works

Digoxin blocks the sodium-potassium pump in heart-muscle cells. This raises the calcium available inside each cell, which strengthens the force of every contraction. Digoxin also acts on the vagus nerve to slow conduction through the AV node, which slows the heart rate and lets the heart fill more fully between beats.

Before you take it

• Digoxin is cleared by the kidneys, so kidney disease raises blood levels. Tell your prescriber about any kidney problems, and expect more frequent blood tests if your kidney function changes.
• Amiodarone and verapamil both raise digoxin blood levels substantially and are among the most important interactions. Combining either with digoxin usually means a lower digoxin dose and closer monitoring.
• Low blood potassium, often caused by diuretics, vomiting, or diarrhoea, makes the heart far more sensitive to digoxin and can cause toxicity even when the digoxin level itself looks normal.
• Tell your prescriber about pregnancy, breastfeeding, and any other heart rhythm problems before you start.

Side effects

Common early effects include mild nausea, loss of appetite, and headache, which often ease as your body adjusts.

Seek urgent medical care for:

• Nausea, vomiting, or loss of appetite that doesn't settle.
• Blurred vision, or seeing yellow-green halos around lights.
• A pulse that is very slow (under 60), skips beats, or feels irregular.
• Confusion, drowsiness, or a marked change in alertness.

Safety essentials

• Digoxin has a narrow therapeutic index: too little and it stops working, too much and it becomes toxic. Regular blood tests measure your digoxin level and keep it in the safe range.
• Amiodarone and verapamil raise digoxin levels significantly, and low potassium increases the heart's sensitivity to it even at a normal digoxin level. Tell every prescriber and pharmacist that you take digoxin before starting any new medicine, and have your potassium checked if you start a diuretic.
• Learn the toxicity signs: nausea, visual halos, and a slow or irregular pulse. Get a blood test and medical review promptly if any appear, rather than waiting for your next routine check.

This page is educational and does not replace advice from a doctor or pharmacist who knows your health history.