Digoxin toxicity results from inhibition of the Na⁺/K⁺-ATPase pump, leading to intracellular calcium overload. It can present as acute overdose (intentional or accidental), chronic accumulation (most common in the ED, often due to renal decline or drug interactions), or acute-on-chronic ingestion. [1-2] Despite declining digoxin prescriptions, poisoning remains frequent due to its narrow therapeutic window. [1]
1. History
- Acute vs. chronic exposure: Determine timing, amount ingested, and whether intentional or accidental [2]
- GI symptoms: Anorexia, nausea, vomiting, diarrhea — present in 30–70% of overdosed patients and often the earliest manifestation [3-4]
- Neurologic: Visual disturbances (classically xanthopsia/yellow-green halos), confusion, disorientation [5-6]
- Cardiac: Palpitations, presyncope, syncope, dyspnea
- Timing: Peak cardiac effects occur 3–6 hours post-ingestion and may persist ≥24 hours [3]
- Medication changes: Recent dose adjustments, new interacting drugs, or changes in renal function
- Important negatives: Deny suicidal intent? Access to plants (foxglove, oleander) or toad-derived ethnopharmaceuticals? [1][7]
2. Alarm Features
- Hemodynamic instability: Hypotension, altered mental status, syncope
- Life-threatening arrhythmias: VT, VF, high-degree AV block, bradyarrhythmia, sinus arrest [3]
- Hyperkalemia (K⁺ >5.5 mEq/L in adults, >6 mEq/L in children) — a marker of severe acute poisoning and predictor of mortality [8]
- Serum digoxin >4 ng/mL with serious arrhythmias [5-6]
- Massive ingestion: ≥10 mg in adults or ≥4 mg (>0.1 mg/kg) in children [8]
- Bidirectional VT — nearly pathognomonic for digoxin toxicity [5]
3. Medications
Drugs that increase digoxin levels (reduce digoxin dose when initiating): [9]
Drugs that cause hypokalemia (potentiate toxicity at therapeutic levels): [4]
Contraindicated in digoxin toxicity
- Calcium for hyperkalemia — concern for myocardial tetany ("stone heart"); evidence is mixed but caution is warranted [1]
- Electrical cardioversion — may precipitate lethal ventricular arrhythmias; if unavoidable, use lowest energy [4]
- Dialysis — not effective for digoxin removal due to large volume of distribution (Class III: No Benefit per ACC/AHA/HRS) [10]
Key treatment: Digoxin-specific Fab antibodies (DigiFab) — the definitive antidote [3][5][8]
4. Diet
- Hypokalemia from poor dietary intake or GI losses sensitizes the myocardium to digoxin toxicity [4]
- Maintain adequate potassium and magnesium intake in chronic digoxin users
- Dehydration and volume depletion can worsen renal function and precipitate toxicity
- Natural cardiac glycoside sources: foxglove tea, oleander, lily of the valley, Bufo toad preparations [1][7]
5. Review of Systems
- Cardiac: Palpitations, chest pain, dyspnea, syncope, presyncope
- GI: Nausea, vomiting, anorexia, abdominal pain, diarrhea [4]
- Neuro: Visual changes (blurred vision, color disturbances, halos), confusion, fatigue, weakness [5]
- Psych: Assess for intentional ingestion/suicidal ideation
- Renal: Decreased urine output (suggests AKI contributing to accumulation)
6. Collateral History and Family History
- Confirm medication list, recent dose changes, and adherence
- Identify recent illness (dehydration, gastroenteritis) that may have impaired renal clearance
- Access to plants or ethnopharmaceuticals containing cardiac glycosides [7]
- Family history is generally not contributory, but assess for inherited conditions affecting renal function
- In pediatric cases, determine accidental ingestion circumstances
7. Risk Factors
- Advanced age [11]
- Impaired renal function — digoxin is primarily renally excreted; prolonged half-life increases accumulation risk [4]
- Low body weight / low lean body mass [9][11]
- Electrolyte abnormalities: Hypokalemia, hypomagnesemia, hypercalcemia [4][11]
- Hypothyroidism [5][12]
- Drug interactions raising digoxin levels (see Medications above) [9]
- Cardiac amyloidosis — increased binding to amyloid fibrils increases susceptibility at therapeutic levels [4]
- Chronic lung disease, dehydration, acute kidney injury [12]
8. Differential Diagnosis
- Hyperkalemia (other causes) — can produce similar bradyarrhythmias and conduction delays
- Beta-blocker or calcium channel blocker toxicity — bradycardia, AV block, hypotension
- Sick sinus syndrome / intrinsic conduction disease — especially in elderly patients already on digoxin
- Acute coronary syndrome — can cause new arrhythmias and GI symptoms
- Organophosphate poisoning — bradycardia, GI symptoms, cholinergic crisis
- Other cardiac glycoside poisoning: Oleander, foxglove, lily of the valley, Bufo toad venom [1][7]
- Hypothyroidism — can mimic and potentiate toxicity
9. Past Medical History
- Heart failure and atrial fibrillation — the primary indications for digoxin use
- Chronic kidney disease — most important risk factor for chronic toxicity [4]
- Prior episodes of digoxin toxicity
- Thyroid disease (hypothyroidism increases sensitivity) [5][12]
- Restrictive or constrictive cardiomyopathies — digoxin may be ineffective or harmful [4]
10. Physical Exam
- Vitals: Bradycardia (most common), tachycardia (with VT), hypotension, irregular pulse
- Cardiac: Irregular rhythm, new murmurs (from hemodynamic changes), signs of heart failure exacerbation
- Neuro: Altered mental status, confusion
- GI: Abdominal tenderness (rare: intestinal ischemia/hemorrhagic necrosis reported) [4]
- Eyes: Visual acuity changes (xanthopsia)
- Skin: Assess perfusion, capillary refill
11. Lab Studies
- Serum digoxin level: Toxicity usually associated with levels >2 ng/mL, though symptoms can occur at lower levels; adverse events increase above 1.2 ng/mL. Draw level at least 6 hours post-dose for steady-state accuracy [3][11]
- Basic metabolic panel: K⁺, Mg²⁺, Ca²⁺, BUN/Cr — critical for identifying predisposing electrolyte abnormalities and renal impairment [4][11]
- Serum potassium: Acute overdose → hyperkalemia (prognostic marker); chronic toxicity → often hypokalemia (precipitant) [1][3]
- Thyroid function: Hypothyroidism potentiates toxicity [5]
- Lactate, troponin: If hemodynamic instability or concern for myocardial injury
- Note: Digoxin levels are unreliable after Fab administration due to assay interference [5-6]
12. Imaging
- Chest X-ray: Assess for pulmonary edema/heart failure exacerbation
- No specific imaging is diagnostic for digoxin toxicity
- Imaging is primarily used to evaluate for alternative diagnoses or complications (e.g., aspiration, pulmonary edema)
13. Special Tests
- Activated charcoal: Consider in acute ingestion regardless of time since ingestion due to enterohepatic recirculation [3-4]
- Poison control consultation: Recommended for all significant exposures
- Point-of-care potassium and glucose
- Continuous cardiac monitoring — mandatory
14. ECG
This is the highest-yield diagnostic tool. Classic findings include: [3][5][11][13]
- "Digitalis effect" (therapeutic, not toxicity): Scooped ST depression ("Salvador Dalí mustache"), shortened QT, T-wave flattening/inversion
- Arrhythmias characteristic of toxicity:
- Bidirectional ventricular tachycardia — nearly pathognomonic [5]
- Atrial tachycardia with AV block (PAT with block) [3][13]
- Accelerated junctional (nodal) rhythm [3]
- New-onset Mobitz type I (Wenckebach) AV block [3]
- Frequent PVCs — especially bigeminy or trigeminy [11]
- Third-degree (complete) heart block [11]
- Regularization of ventricular rate in atrial fibrillation (suggests complete heart block with junctional escape)
- Key pearl: The hallmark is enhanced automaticity + impaired conduction occurring simultaneously [5][13]
15. Assessment
Digoxin toxicity should be classified by exposure type and severity: [2]
- Acute ingestion: Typically intentional overdose; presents with GI symptoms → hyperkalemia → arrhythmias. Peak cardiac effects at 3–6 hours [3]
- Chronic toxicity: More insidious; often precipitated by renal decline, dehydration, or new drug interaction. GI and neurologic symptoms may predominate initially [1]
- Severity stratification: Serum digoxin >2 ng/mL with symptoms = significant toxicity; >4 ng/mL with arrhythmias = severe; K⁺ >5.5 = high mortality risk [8][10]
- Complications: Cardiac arrest (VF, asystole), refractory hyperkalemia, heart failure exacerbation post-Fab [5]
16. Treatment Plan
Initial stabilization
- ABCs, IV access, continuous cardiac monitoring
- Discontinue digoxin immediately [5-6]
Mild toxicity (minor GI symptoms, minor rhythm disturbances, stable hemodynamics):
- Hold digoxin, monitor on telemetry
- Correct hypokalemia (target K⁺ 4.0–5.5 mEq/L) and hypomagnesemia [3-4]
- Avoid potassium in patients with bradycardia or heart block [3]
- IV magnesium if ventricular arrhythmias present [5]
Severe toxicity — Digoxin-specific Fab antibodies (DigiFab): [8]
Indications per the DigiFab label:
- Life-threatening arrhythmias (VT, VF, high-degree AV block, sinus arrest)
- K⁺ >5.5 mEq/L (adults) or >6 mEq/L (children) with progressive toxicity
- Ingestion ≥10 mg (adults) or ≥4 mg / >0.1 mg/kg (children)
- Serum digoxin ≥10 ng/mL (acute) or >6 ng/mL (chronic in adults) [8]
Fab dosing: [8]
- Titrated dosing (1–2 vials at a time) has been shown to be safe and effective, using only 25–35% of the calculated full neutralizing dose, with significant cost savings [14]
- Response typically occurs within 30–45 minutes [7][10]
- Fab is 80–90% effective in reversing signs and symptoms [3]
- Monitor for hypokalemia post-Fab (potassium shifts intracellularly as Na⁺/K⁺-ATPase function is restored) [5][10]
Additional considerations
- Atropine: May be tried for symptomatic bradycardia but has variable effectiveness [7]
- Temporary pacing: For refractory AV block or asystole; variable capture in digoxin toxicity [5]
- Activated charcoal: In acute ingestion, even late, due to enterohepatic recirculation [3-4]
- Avoid calcium for hyperkalemia in this setting (risk of "stone heart") [1]
- Lidocaine/phenytoin: Case reports only; no high-quality evidence; limited role [7][15]
The 2018 ACC/AHA/HRS Bradycardia Guidelines provide an acute bradycardia algorithm that includes digoxin-specific management:
17. Disposition
Admit (ICU/telemetry)
- Any life-threatening arrhythmia or hemodynamic instability
- Digoxin-Fab administration (monitor for rebound toxicity, hypokalemia, and recurrence of underlying arrhythmia)
- Hyperkalemia (K⁺ >5.5 mEq/L)
- Serum digoxin >2 ng/mL with symptoms
- Intentional ingestion (psychiatric evaluation required)
- Significant renal impairment with elevated levels
Observation
- Mildly elevated digoxin levels with minor GI symptoms only
- Asymptomatic patients after acute ingestion (observe ≥6 hours for delayed cardiac effects) [3]
Discharge (rare from ED)
Consult triggers
- Toxicology/Poison Control — all significant exposures
- Cardiology — refractory arrhythmias, need for temporary pacing
- Nephrology — life-threatening hyperkalemia refractory to Fab (hemodialysis for K⁺, not digoxin removal) [10]
- Psychiatry — intentional ingestion
18. Follow-Up / Return Precautions
- Rebound toxicity: Free digoxin can rebound after Fab wears off (half-life ~15–20 hours); monitor for recurrence of symptoms, especially in chronic toxicity with large body stores [14]
- Digoxin level monitoring: Unreliable for 1–2 weeks after Fab due to assay interference (measures bound + free digoxin) [5-6]
- Outpatient follow-up: Recheck renal function, electrolytes, and digoxin level (once Fab has cleared) within 1 week
- Medication reconciliation: Review and adjust interacting medications; consider whether digoxin should be continued at all
- Return precautions: Return immediately for palpitations, syncope/presyncope, recurrent nausea/vomiting, visual changes, or lightheadedness
- Expected course: With Fab treatment, most patients improve within 30–45 minutes; 54% of patients presenting in cardiac arrest survived hospitalization in one series [5][7]
References
1. 2023 American Heart Association Focused Update on the Management of Patients With Cardiac Arrest or Life-Threatening Toxicity Due to Poisoning: An Update to the American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. — Lavonas EJ, Akpunonu PD, Arens AM, et al. Circulation. 2023.
2. Expert Consensus on the Diagnosis and Management of Digoxin Toxicity. — Hack JB, Wingate S, Zolty R, Rich MW, Hauptman PJ. The American Journal of Medicine. 2025.
3. FDA Drug Label. — Updated date: 2025-10-17. Food and Drug Administration.
4. FDA Drug Label. — Updated date: 2025-04-10. Food and Drug Administration.
5. 2017 AHA/ACC/HRS Guideline for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society. — Al-Khatib SM, Stevenson WG, Ackerman MJ, et al. Heart Rhythm. 2018.
6. 2017 AHA/ACC/HRS Guideline for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society. — Al-Khatib SM, Stevenson WG, Ackerman MJ, et al. Journal of the American College of Cardiology. 2018.
7. Part 10: Adult and Pediatric Special Circumstances of Resuscitation: 2025 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. — Cao D, Arens AM, Chow SL, et al. Circulation. 2025.
8. FDA Drug Label. — Updated date: 2015-11-06. Food and Drug Administration.
9. 2009 Focused Update Incorporated Into the ACC/AHA 2005 Guidelines for the Diagnosis and Management of Heart Failure in Adults a Report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines Developed in Collaboration With the International Society for Heart and Lung Transplantation. — Hunt SA, Abraham WT, Chin MH, et al. Journal of the American College of Cardiology. 2009.
10. 2018 ACC/AHA/HRS Guideline on The evaluation and Management Of patients With Bradycardia and Cardiac conduction Delay: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society. — Writing Committee Members, Kusumoto FM, Schoenfeld MH, et al. Heart Rhythm. 2019.
11. FDA Drug Label. — Updated date: 2024-12-05. Food and Drug Administration.
12. Factors Affecting Tolerance to Digitalis. — Surawicz B. Journal of the American College of Cardiology. 1985.
13. Drug-Induced Arrhythmias: A Scientific Statement From the American Heart Association. — Tisdale JE, Chung MK, Campbell KB, et al. Circulation. 2020.
14. Clinical Experience With Titrating Doses of Digoxin Antibodies in Acute Digoxin Poisoning. (ATOM-6). — Chan BS, Isbister GK, Chiew A, Isoardi K, Buckley NA. Clinical Toxicology. 2022.
15. ACC/AHA/ESC 2006 Guidelines for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death: A Report of the American College of Cardiology/American Heart Association Task Force and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Develop Guidelines for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death). — European Heart Rhythm Association, Heart Rhythm Society, Zipes DP, et al. Journal of the American College of Cardiology. 2006.
16. 2018 ACC/AHA/HRS Guideline on The Evaluation and Management of Patients With Bradycardia and Cardiac Conduction Delay: Executive Summary: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines, and the Heart Rhythm Society. — Kusumoto FM, Schoenfeld MH, Barrett C, et al. Journal of the American College of Cardiology. 2019.