Digoxin Testing

Written by Heather Ross | Published on July 25, 2012
Medically Reviewed by George Krucik, MD


Digoxin is a medication that contains cardiac glycosides, used to treat heart failure and irregular heartbeats. A digoxin test is a blood test that determines the level of the medication in your blood to ensure that you are not receiving too much or too little of the drug.

Why Is a Digoxin Test Performed?

Cardiac glycoside, the active ingredient in digoxin, is a potentially poisonous chemical if taken in large amounts or over a long period of time. It is important that your doctor regularly checks the amount of digoxin in your blood. This is because most patients need to take adequate doses of the drug for it to be effective. Young children and the elderly are at an especially high risk for toxicity (digoxin overdose).

Your doctor will likely order several digoxin tests when you first start using the drug to establish the appropriate dose. You doctor should continue to order the tests at regular intervals for as long as you are taking the drug, or if he or she suspects that you are receiving too much or too little of the medication.

If the level of digoxin in your system is too low, you may experience symptoms of heart failure. These symptoms include:

  • fatigue
  • shortness of breath
  • edema (swelling in your hands and feet)

If the level of the drug in your system is too high, you may suffer symptoms of an overdose, including:

  • dizziness
  • seeing yellow or green halos around objects
  • diarrhea
  • vomiting
  • difficulty breathing
  • irregular heartbeats
  • confusion
  • fainting
  • headaches
  • muscle weakness
  • skin rashes

How Is a Digoxin Test Performed?

Your doctor will check your levels of digoxin by testing a sample of your blood. Usually, you will be asked to go to an outpatient clinical laboratory to have your blood sample taken. The healthcare provider at the lab will draw blood from your arm or hand with a needle.

Talk to your doctor about whether or not to take your usual medications before the test. Some prescription, over-the-counter, and supplemental drugs can affect the level of digoxin in your body and therefore the effectiveness of the test. These drugs include:

  • hydrocortisone
  • prednisone
  • progesterone
  • ginseng

Be sure to tell your doctor about all medications and supplements you are taking in addition to digoxin.

What Risks Are Associated with Digoxin Tests?

The risk of complications from having your blood drawn is very slight. Some people experience mild pain or dizziness while having their blood sample taken. After the test, a bruise, slight bleeding, an infection, or a hematoma (a blood-filled bump under your skin) could develop at the puncture site.

What Do the Test Results Mean?

The normal level of digoxin is between 0.5 and 2.0 nanograms of medication per milliliter of blood (ng/ml) if you are being treated for heart failure. If you are being treated for heart arrhythmia, the normal amount of the drug is between 1.5 and 2.0 ng/ml. If your tests results fall outside the normal range, your doctor will adjust your digoxin dose accordingly.

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