What Are the Uses and Side Effects of Digoxin?

October 9, 2025 •

5 min read

Derived from the foxglove plant, digoxin is one of the oldest cardiovascular drugs still in use, with a history dating back to the 18th century. A cardiac glycoside, this medication is used to treat specific heart conditions, but understanding the uses and side effects of digoxin is crucial for safe treatment.

Quick Summary

Digoxin is a cardiac glycoside used to manage heart failure and atrial fibrillation by strengthening heart contractions and controlling heart rate. It has a narrow therapeutic range, and side effects like gastrointestinal issues, vision changes, and cardiac arrhythmias may signal toxicity.

Key Points

Positive Inotropic Effect: Digoxin increases the strength of heart contractions, which helps the heart pump more blood with each beat.
Rate Control for Arrhythmias: Digoxin slows the heart rate, making it a useful medication for controlling the rapid ventricular response seen in chronic atrial fibrillation.
Narrow Therapeutic Index: Due to its narrow therapeutic range, the difference between an effective dose and a toxic dose of digoxin is small, requiring careful dosing and monitoring.
Signs of Toxicity: Early signs of digoxin toxicity often include nausea, vomiting, visual disturbances (yellow or blurred vision), and fatigue.
Cardiac Risks: In toxic amounts, digoxin can cause life-threatening arrhythmias, such as severe bradycardia or ventricular fibrillation.
Risk Factors for Toxicity: Impaired kidney function, electrolyte imbalances (especially low potassium), and drug interactions can increase the risk of digoxin toxicity.
Monitoring is Key: Regular blood tests are necessary to ensure digoxin levels and electrolytes remain within a safe range.

What Is Digoxin and How Does It Work?

Digoxin is a medication derived from the Digitalis lanata (foxglove) plant and belongs to a class of drugs known as cardiac glycosides. It is prescribed for certain heart conditions to help the heart function more efficiently. Digoxin works through two primary mechanisms that affect the heart's function and rhythm:

Positive Inotropic Effect: Digoxin increases the force and efficiency of cardiac muscle contraction. It does this by inhibiting the sodium-potassium ATPase pump in heart muscle cells, which causes an increase in intracellular sodium. This, in turn, triggers an influx of intracellular calcium, making more calcium available for the proteins that cause the heart muscle to contract.
Negative Chronotropic Effect: Digoxin also slows the heart rate by acting on the parasympathetic nervous system. It enhances vagal tone, which slows electrical conduction through the sinoatrial (SA) and atrioventricular (AV) nodes. This effect is particularly useful for controlling the rapid ventricular response seen in conditions like atrial fibrillation.

Approved Uses for Digoxin

Digoxin is indicated for the treatment of certain cardiovascular conditions, primarily for symptom management. Its uses have become more limited in recent decades as newer, more effective and safer therapies have emerged.

Heart Failure: Digoxin is used to treat mild to moderate heart failure, often in conjunction with other medications like diuretics and ACE inhibitors. It helps to improve symptoms such as reduced exercise capacity, swelling, and shortness of breath, as it increases cardiac output. However, it is important to note that studies have shown digoxin improves quality of life and reduces hospitalizations for heart failure, but it does not improve survival.
Atrial Fibrillation: Digoxin can be used for rate control in patients with chronic atrial fibrillation. It is often reserved for patients who have not responded adequately to other first-line therapies, such as beta-blockers or calcium channel blockers.

Common and Serious Side Effects

As with any medication, digoxin can cause side effects. Due to its narrow therapeutic index (meaning the effective dose is very close to a toxic dose), careful monitoring is required. Side effects can be a sign that digoxin levels are becoming toxic.

Common Side Effects:

Gastrointestinal Issues: The most common early signs of digoxin toxicity are often gastrointestinal. These include nausea, vomiting, diarrhea, and loss of appetite.
Neurological Effects: Some patients experience dizziness, headache, weakness, confusion, or fatigue. Older adults may be particularly susceptible to confusion and delirium.
Visual Disturbances: Digoxin can cause characteristic visual changes, such as blurred vision, seeing halos around bright lights, or altered color perception (seeing yellow or green hues).

Serious Side Effects (Signs of Digoxin Toxicity):

Cardiac Arrhythmias: Digoxin can cause a wide range of irregular heart rhythms, which can be fatal. While it is used to treat arrhythmias like atrial fibrillation, toxic levels can cause new, dangerous ones. These can include:
- Severe sinus bradycardia (slow heart rate)
- Atrioventricular (AV) block
- Ventricular tachycardia or fibrillation
Electrolyte Imbalances: Toxicity is more likely with low potassium (hypokalemia) or low magnesium (hypomagnesemia) levels. Conversely, acute overdose can lead to high potassium (hyperkalemia).
Other Manifestations: In rare cases, more severe effects can occur, including gynecomastia (breast enlargement in men) with long-term use and intestinal ischemia.

Risks of Digoxin Toxicity and Monitoring

Digoxin toxicity is a serious and potentially life-threatening complication that can occur with high serum levels, though toxicity can also occur at lower levels in susceptible patients.

Factors that increase the risk of digoxin toxicity include:

Impaired kidney function, as digoxin is primarily eliminated by the kidneys.
Electrolyte imbalances, particularly low potassium and low magnesium.
Advanced age, as older patients are more sensitive to the drug's effects.
Drug interactions with other medications (e.g., amiodarone, verapamil) that can increase digoxin levels.
Acute illness or dehydration.

Monitoring Digoxin Therapy:

Because of its narrow therapeutic window, regular blood tests are crucial to monitor serum digoxin levels, especially when starting the medication or adjusting the dose.
Electrolyte levels (potassium, magnesium) and kidney function should also be checked regularly.
Patients and caregivers should be educated on the symptoms of toxicity, as many are non-specific and can be confused with other conditions.

Digoxin vs. Other Heart Medications: A Comparison

For conditions like heart failure and atrial fibrillation, digoxin is often part of a broader treatment plan and may not be a first-line therapy. Here's how it compares to other medications that serve similar purposes:


Feature	Digoxin	Beta-Blockers (e.g., Metoprolol)	ACE Inhibitors (e.g., Lisinopril)
Primary Function	Increases contractility (inotropy) and slows heart rate (chronotropy).	Block adrenaline's effects, slowing heart rate and reducing blood pressure.	Block the production of a hormone that constricts blood vessels, lowering blood pressure and reducing heart strain.
Main Use(s)	Symptom management for heart failure, rate control for atrial fibrillation.	First-line therapy for many heart conditions, including heart failure and rate control for atrial fibrillation.	First-line therapy for heart failure, high blood pressure.
Effect on Mortality	Improves quality of life and reduces hospitalization, but no proven survival benefit in heart failure.	Proven to reduce mortality in heart failure patients.	Proven to reduce mortality in heart failure patients.
Therapeutic Window	Narrow therapeutic index; high risk of toxicity at slightly elevated levels.	Wide therapeutic window; lower risk of toxicity compared to digoxin.	Generally wide therapeutic window.
Common Side Effects	Nausea, vomiting, diarrhea, visual changes, fatigue.	Dizziness, fatigue, bradycardia, hypotension.	Cough, dizziness, headache.
Risk of Toxicity	High risk, especially with electrolyte imbalance or renal dysfunction.	Lower risk; overdose can cause severe bradycardia and hypotension.	Lower risk; overdose can cause severe hypotension.

Conclusion

Digoxin remains a valuable medication for managing specific cardiovascular conditions like heart failure and chronic atrial fibrillation, especially when other treatments are insufficient. However, its use requires careful management due to its narrow therapeutic index and the potential for serious side effects, including life-threatening cardiac arrhythmias. Patients on digoxin must be closely monitored by their healthcare provider for changes in kidney function, electrolyte levels, and signs of toxicity. By understanding the uses and side effects of digoxin and adhering to monitoring protocols, patients can maximize its benefits while minimizing risks.

For more detailed information, consult the U.S. Food and Drug Administration (FDA) prescribing information for Lanoxin.

Frequently Asked Questions

Unlike many first-line heart medications like beta-blockers or ACE inhibitors, digoxin primarily works by strengthening heart contractions and slowing heart rate, rather than focusing on blood pressure reduction or survival benefits.

Your healthcare provider will determine the exact schedule, but you can expect to have blood tests after starting the medication, with a dose change, and at regular intervals thereafter. This is to check your digoxin levels, electrolytes, and kidney function.

If you miss a dose, take it as soon as you remember. However, if it is almost time for your next dose, skip the missed one and continue your regular schedule. Do not double doses. If you miss doses for more than a day, contact your doctor for instructions.

The earliest signs often involve gastrointestinal issues such as nausea, vomiting, or a persistent loss of appetite. Neurological symptoms like fatigue or confusion, and visual changes such as blurred or yellow vision, can also appear.

Yes, but be mindful of the timing. High-fiber foods and supplements can interfere with digoxin's absorption. It is generally recommended to take digoxin at least one to four hours before or after a high-fiber meal or supplement.

To reduce your risk, take your medication exactly as prescribed, inform your doctor of any new medications or supplements, and attend all scheduled monitoring appointments. You should also recognize the signs of toxicity and seek medical help promptly if they appear.

Older adults can take digoxin, but they are more sensitive to its effects and more likely to experience age-related kidney or heart issues. For this reason, elderly patients usually receive lower doses and require close monitoring to prevent toxicity.