Digoxin: Toxicity and Safe Administration
What it is
Digoxin inhibits the sodium-potassium ATPase pump in myocardial cells, which raises intracellular calcium and strengthens contraction; it also increases vagal tone, slowing the heart rate and AV conduction. It treats symptoms of heart failure with reduced ejection fraction and controls the ventricular rate in atrial fibrillation. Its therapeutic range is narrow: potassium competes with digoxin at the pump, so hypokalemia increases its effect, and digoxin is excreted by the kidneys, so renal impairment and older age raise the level.
What the NCLEX focuses on
- Count the apical pulse for 1 full minute before every dose; hold and report an adult pulse below 60/min or a new irregular rhythm.
- Early toxicity is gastrointestinal: anorexia, nausea and vomiting; then confusion, fatigue, blurred or yellow-green vision and halos.
- Cardiac toxicity: bradycardia, AV block and new dysrhythmias such as premature ventricular contractions, bigeminy and ventricular tachycardia.
- Toxicity risk rises with hypokalemia, hypomagnesemia, hypercalcemia, renal impairment and older age, and with amiodarone or verapamil, which raise the digoxin level.
- A loop or thiazide diuretic lowers potassium, so a client taking both needs potassium monitoring.
- Draw the level at least 6 to 8 hours after the last dose; an earlier sample is falsely high.
- Digoxin immune fab treats life-threatening toxicity; afterward, monitor for hypokalemia and returning heart failure or rapid atrial fibrillation.
Priority nursing actions
- Count the apical pulse for 1 full minute and review the latest potassium, creatinine and digoxin level.
- Hold the dose and notify the provider for a pulse below 60/min, a new rhythm, or symptoms of toxicity.
- Place the client on a cardiac monitor and obtain the digoxin level, potassium, magnesium and an ECG as prescribed.
- Correct hypokalemia as prescribed.
- Give digoxin immune fab as prescribed for life-threatening dysrhythmias or severe toxicity and monitor rhythm and potassium closely.
Numbers to know
| Value | Normal or target | Why it matters |
|---|---|---|
| Apical pulse, adult | Hold if below 60/min | Bradycardia and heart block |
| Apical pulse, child | Hold if below 70/min (infant below 90 to 110/min) or per prescribed limit | Children have higher normal rates |
| Digoxin level | 0.5 to 2.0 ng/mL (0.6 to 2.6 nmol/L) | Above 2.0 ng/mL suggests toxicity |
| Potassium | 3.5 to 5.0 mEq/L (3.5 to 5.0 mmol/L) | Hypokalemia causes toxicity even at a normal digoxin level |
| Level timing | At least 6 to 8 hours after the last dose | Earlier samples reflect distribution, not true level |
Common exam traps
- Choosing to give digoxin with an apical pulse of 54/min: wrong because the dose is held and the provider notified.
- Choosing a 15- or 30-second radial count: wrong because a full-minute apical count detects bradycardia and a pulse deficit.
- Choosing to attribute new nausea and poor appetite in an older adult to a stomach virus: wrong because these are early signs of toxicity.
- Choosing to treat a potassium of 3.0 mEq/L as only a diuretic issue: wrong because hypokalemia makes digoxin toxicity more likely.
- Choosing protamine or flumazenil for digoxin overdose: wrong because the antidote is digoxin immune fab.
What to teach
- Take digoxin at the same time each day; never double a missed dose, and skip it if more than 12 hours late.
- If taught, count the pulse for 1 full minute before each dose; report a pulse below 60/min or a new irregular beat.
- Report nausea, vomiting, loss of appetite, blurred or yellow-green vision, halos or confusion.
- Keep laboratory appointments; take antacids at least 2 hours apart from digoxin and check with the prescriber before taking any herbal product.
Client handout: Taking Digoxin Safely (nurse guide and printable patient handout).
Try 2 NCLEX-style questions on this topic
From the NCLEXPace question bank. Pick your answers, then check them inside NCLEXPace.
A hospitalized client is scheduled to receive a morning dose of digoxin. Which assessment should the nurse perform immediately before giving the drug?
Select the best answer.
- A. Apical pulse for 1 minute
- B. Respiratory rate and depth
- C. Capillary blood glucose
- D. Blood pressure in both arms
A client taking digoxin and furosemide has a potassium level of 3.0 mEq/L. Which statement about this finding is accurate?
Select the best answer.
- A. It raises digoxin toxicity risk even at an unchanged level
- B. The potassium level becomes clinically important only if the client also develops nausea, visual changes, bradycardia, or another symptom associated with digoxin toxicity
- C. The low potassium is mainly a furosemide monitoring issue and does not substantially change the safety of digoxin when the prescribed digoxin dose is unchanged
- D. The potassium of 3.0 mEq/L indicates that the serum digoxin concentration has also risen above the therapeutic range and should be treated as digoxin toxicity
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Cardiac Drugs on the NCLEX: Digoxin, ACE Inhibitors and NitratesTherapeutic Drug Levels: The Four You Must KnowPotassium on the NCLEX: Why K+ Is the Exam's Favourite ElectrolyteMore tips on Pharmacology
Therapeutic Drug Levels: Ranges, Timing and ToxicityKnow the ranges for digoxin, lithium, phenytoin and vancomycin, when to draw each level, and the toxicity signs that mean hold the dose.High-Alert Medications: Safeguards the NCLEX TestsIdentify ISMP high-alert drugs, use independent double checks, and give IV potassium, insulin, heparin and opioids safely.Dosage Calculations Without ErrorsUse one method for tablets, liquids, weight-based doses and IV rates, convert units first, and spot answers that cannot be right.Sources
- Harding MM, Kwong J, Hagler D, Reinisch C. Lewis's Medical-Surgical Nursing: Assessment and Management of Clinical Problems. 12th ed. Elsevier; 2023; Chapter: Heart Failure.
- Heidenreich PA, Bozkurt B, Aguilar D, et al. 2022 AHA/ACC/HFSA Guideline for the Management of Heart Failure. Circulation. 2022;145(18):e895-e1032.
- Digoxin tablets [package insert]. DailyMed, US National Library of Medicine.
- Digoxin immune fab (ovine) [package insert]. DailyMed, US National Library of Medicine.
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