Summary
What is digoxin?
Digoxin is a medication that is used to treat heart failure and irregular heart rhythms, known as atrial fibrillation. It strengthens the contractions of the heart and helps it to pump blood more efficiently. In this way, it can lessen the strain on the heart and control the rate and rhythm of the heartbeat.
Under normal circumstances, if you have heart disease or irregular heartbeat, you will be prescribed blood pressure medications. Digoxin can be toxic, and for this reason it would usually only be prescribed if:
Having the correct dose of Digoxin is important because having too much in your body can cause serious side effects including confusion, dizziness, nausea, vomiting and changes to your heartbeat. On the other hand, digoxin will not work if there is not enough in your body to be effective.
If you are prescribed digoxin you will need to have regular blood tests to measure the level in your body to make sure it is within certain limits that have been established as effective but safe for you.
How does digoxin work?
Digoxin works by increasing in the amount of sodium in your heart cells. In turn, this raises the amount of calcium which affects the heart’s electrical system and slows the signals that tell your heart to beat. Slowing down these signals brings down your heart rate.
When to get tested?
A test to measure digoxin is ordered at the beginning of drug therapy to make sure you are having the correct dosage. Digoxin takes about one to two weeks to reach a steady level in the blood and in the heart. A test done at two weeks after your first dose will accurately reflect whether you are receiving the right amount of digoxin. After that, digoxin levels will be monitored routinely by your doctors for as long as you are taking the medication.
Young children and older adults are at the highest risk for toxicity. Certain health conditions can affect levels of digoxin and its ability to control your symptoms. These include:
Digoxin is cleared from your system by your kidneys. Tell your doctor if you have or have had known kidney problems. Your doctor may want to monitor blood potassium levels since low levels of potassium can result in symptoms of toxicity.
Timing of the digoxin blood test is important. The sample should be drawn at least 6 to 8 hours after the last dose. Many times, the blood sample will be drawn just before the next dose is to be taken. Timing of the sample collection is important because if the sample is drawn too soon after a dose, the results of the test may be inaccurate and show a toxic level when that is not the case.
If the level of digoxin in your system is too low, you may experience the symptoms of heart failure such as tiredness, shortness of breath and swelling in your hands and feet.
High levels can lead to signs of toxicity, including:
In cases where toxic levels of digoxin are measured, anti-digoxin antisera (a medication that stops digoxin in the body from working) may be administered to reverse the effects of the drug.
Having the test
Sample
Blood
Any preparation?
Tell your doctor about all medications and supplements you are taking including over the counter medications that don’t need a prescription. Many prescribed and over-the-counter drugs can affect the level and effectiveness of digoxin in your system. These include certain blood pressure medications, antacids and anti-inflammatory medications, such as nonsteroidal anti-inflammatory drugs.
Your results
Reading your test report
Your results will generally be presented along with those of your other tests on the same form. You will see separate columns or lines for each of these tests.
Therapeutic range
Most people find that their symptoms improve when their digoxin levels are within these ranges (called the therapeutic range).
| 0.5-1.0 µg/L | If you have heart failure |
| 0.5-1.8 µg/L | If you have atrial fibrillation |
| µg/L stands for micrograms per litre. Toxic levels are when the digoxin level is greater than 2.0 µg/L. | |
It is important to note that everyone’s response to medications is different and other factors such as kidney function or concurrent medications may be involved. If your symptoms have not improved or if you are experiencing side effects, tell your doctors immediately. They may need to adjust your dose.
If your results are flagged as high or low this does not necessarily mean that anything is wrong. Your doctor needs to take your medical history to help interpret your result.
Questions to ask your doctor
The choice of tests your doctor makes will be based on your medical history and symptoms. It is important that you tell them everything you think might help.
You play a central role in making sure your test results are accurate. Do everything you can to make sure the information you provide is correct and follow instructions closely.
Talk to your doctor about any medications you are taking. Find out if you need to fast or stop any particular foods, medications or supplements. These may affect your results. Ask:
More information
Pathology and diagnostic imaging reports can be added to your My Health Record. You and your healthcare provider can now access your results whenever and wherever needed.
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