Eduovisual
Emergency & Toxicology
Digoxin toxicity: recognition and Fab fragment use
— Narrow therapeutic index: target 0.5–0.9 ng/mL for heart failure (DIG trial); higher levels (1.0–2.0) historically used for rate control in atrial fibrillation but increase mortality.
— Toxic threshold loosely >2.0 ng/mL, but toxicity is clinical — patients with "therapeutic" levels can be toxic if hypokalemic, hypomagnesemic, or hypercalcemic.
— Elderly patient on digoxin for HFrEF or AFib presenting with nausea, vomiting, anorexia, confusion, or visual disturbances (yellow-green halos, xanthopsia).
— Any digoxin user with new bradyarrhythmia, AV block, or bidirectional VT.
— Acute ingestion (suicidal or accidental, including pediatric exploratory ingestion or plant exposures — oleander, foxglove, lily of the valley, red squill, Bufo toad venom).
— Patients with acute kidney injury on chronic digoxin (volume depletion from diuretics, ACEi, or gastroenteritis is the classic precipitant).
— Acute: young, intentional overdose, hyperkalemia (from ATPase blockade), GI symptoms dominant, level very high, fewer cardiac comorbidities → can tolerate slightly higher levels before arrhythmia.
— Chronic: elderly, on diuretics, hypokalemia and hypomagnesemia common, more arrhythmias at lower levels, vague neuropsychiatric and GI complaints often misdiagnosed as dementia, depression, or gastroenteritis.
Board pearl: Hyperkalemia >5.0 mEq/L in acute digoxin toxicity predicts mortality and is itself an indication for digoxin-specific Fab fragments — the Bismuth criteria from the original 1973 cohort showed 100% mortality at K+ >5.5 without antidote.
— Anorexia, nausea, vomiting, abdominal pain, diarrhea.
— Often misattributed to viral gastroenteritis in elderly outpatients, who then become volume-depleted, develop AKI, and spiral into worsening toxicity.
— Fatigue, weakness, headache, dizziness.
— Confusion, delirium, hallucinations — especially in elderly; frequently mislabeled as dementia progression or UTI delirium.
— Seizures are rare but reported in massive overdose.
— Xanthopsia (yellow vision), blurred vision, halos around lights, scotomata, photophobia, altered color perception (chromatopsia).
— Van Gogh's late "yellow period" is the legendary (debated) clinical correlate.
— Palpitations, syncope, presyncope, dyspnea from worsening rate control or new arrhythmia.
— Paradoxically, a digoxin-toxic AFib patient may present with regularized ventricular response (junctional escape) — a red flag.
— Recent dose changes, new prescriptions (especially amiodarone, verapamil, diltiazem, quinidine, propafenone, spironolactone, clarithromycin, itraconazole — all raise levels).
— New diuretic or worsening renal function.
— Recent vomiting/diarrhea (volume loss → AKI → accumulation).
— Herbal or alternative ingestions (foxglove tea, oleander).
— Intent: suicidal ideation, access to others' medications.
Step 3 management: In an outpatient elderly HF patient on digoxin who reports "stomach flu," always check a digoxin level, BMP, and magnesium before sending home — gastroenteritis is the classic precipitant of chronic toxicity, and a missed diagnosis is a board-favorite malpractice stem.
Key distinction: Acute toxicity = GI + hyperkalemia + very high level; chronic toxicity = neuropsychiatric + visual + arrhythmia + modestly elevated level + hypokalemia from concurrent diuretics.
— Bradycardia — sinus brady, sinus arrest, or junctional bradycardia.
— Hypotension if cardiogenic shock develops from refractory bradyarrhythmia or VT.
— Hypertension is atypical; raises suspicion for alternate toxidrome.
— Hypothermia possible in obtunded elderly.
— Irregular pulse may regularize in AFib patient as AV block develops and junctional rhythm takes over — "regularized AFib" is pathognomonic for digoxin toxicity until proven otherwise.
— Variable S1 intensity, cannon A waves if AV dissociation present.
— Signs of underlying HF: elevated JVP, crackles, S3, peripheral edema — important because these patients have limited reserve.
— Altered mental status ranging from mild confusion to obtundation.
— Visual acuity/color vision testing may reveal xanthopsia.
— Generalized weakness; focal deficits should prompt stroke workup.
— Dry mucous membranes, poor skin turgor from vomiting/diarrhea — these signal AKI risk and ongoing accumulation.
— Mild abdominal tenderness; mesenteric ischemia rarely reported in severe toxicity (digoxin-induced vasoconstriction).
— Determine if patient is stable bradyarrhythmia (asymptomatic, normotensive) vs unstable (hypotension, altered mental status, ischemic chest pain, acute HF) — drives urgency of Fab administration.
— Assess perfusion: capillary refill, mentation, urine output, lactate.
CCS pearl: On a CCS case, order continuous cardiac monitoring, IV access ×2, BMP, magnesium, digoxin level, ECG, and place the patient in a monitored bed as your first orders for any suspected digoxin toxicity — do not advance the clock significantly until Fab decision is made.
Board pearl: Any new AV block + GI symptoms + elderly + diuretic use = check a digoxin level before ordering a head CT for "delirium."
— Sinus bradycardia, first-degree AV block — earliest, often "therapeutic effect" overlap.
— PACs, PVCs, atrial tachycardia with block (classic), junctional rhythms, accelerated junctional tachycardia.
— Bidirectional ventricular tachycardia — nearly pathognomonic (also seen in catecholaminergic polymorphic VT and aconite poisoning).
— "Scooped" or "hockey-stick" ST depression (Salvador Dalí mustache sign) — reflects digitalis effect, NOT toxicity per se. Present at therapeutic levels.
— High-grade AV block, complete heart block, ventricular fibrillation in severe cases.
— Draw at least 6 hours post-ingestion for acute overdose; earlier levels reflect distribution phase and are misleadingly high (digoxin has large Vd ~5–7 L/kg).
— For chronic toxicity, any-time level is interpretable in context.
— Level does not strictly correlate with toxicity — treat the patient, not the number.
— Potassium: hyperkalemia in acute; hypokalemia in chronic (worsens toxicity).
— Magnesium: hypomagnesemia potentiates toxicity — repletion is therapeutic.
— Calcium: hypercalcemia worsens toxicity; avoid IV calcium historically (the "stone heart" concern is now disputed but still board-tested as contraindicated).
Board pearl: Hyperkalemia in acute digoxin toxicity is treated with Fab fragments, not insulin/glucose/calcium — calcium specifically should be avoided per traditional teaching, and Fab will correct K+ within hours.
— After Fab administration, total digoxin levels become uninterpretable because most assays measure both free and Fab-bound digoxin — levels appear paradoxically elevated (often >20 ng/mL) for days to weeks.
— Free digoxin levels (rarely available) or clinical response guide further management.
— Do not redose Fab based on a high post-Fab total level alone.
— Minimum 24 hours after Fab in stable patients; longer if renal impairment (Fab-digoxin complex normally cleared renally; rebound toxicity possible in dialysis-dependent patients as digoxin redistributes from tissues).
— Assess baseline LV function, especially if considering long-term digoxin discontinuation vs resumption.
— Evaluate for structural causes of arrhythmia.
— Acetaminophen, salicylate, ethanol levels; urine drug screen; ECG for QT/QRS to rule out TCA or sodium channel blockers.
— Psychiatric evaluation once medically stable.
— Foxglove (Digitalis purpurea/lanata), oleander (Nerium oleander), yellow oleander (Thevetia peruviana), lily of the valley (Convallaria majalis), red squill, Bufo toad secretions (bufadienolides).
— Standard digoxin immunoassay cross-reacts variably with these — a positive level in a non-prescribed patient suggests plant/animal source. Fab is still effective, though sometimes higher doses required.
— Found in neonates, pregnancy, renal failure, liver failure — can produce false-positive low-level digoxin readings; clinical correlation essential.
Key distinction: Post-Fab total digoxin level is meaningless and should not be used to guide retreatment — rely on clinical signs, ECG, and serum potassium normalization.
— Life-threatening arrhythmia attributable to digoxin: ventricular tachycardia/fibrillation, hemodynamically unstable bradyarrhythmia, high-grade AV block unresponsive to atropine.
— Hyperkalemia >5.0–5.5 mEq/L in the setting of acute digoxin toxicity (independent mortality predictor).
— Acute ingestion ≥10 mg in adults or ≥4 mg in children.
— Steady-state serum digoxin level >10–15 ng/mL at any time, or >6 ng/mL after acute ingestion at 6+ hours.
— End-organ dysfunction from toxicity: altered mental status, renal failure, shock.
— Chronic toxicity with significant symptoms even at lower levels (e.g., 4–6 ng/mL) in elderly with arrhythmia or hemodynamic compromise.
— Cardiac glycoside plant or toad venom ingestion with toxicity.
— Discontinuation of digoxin and offending interacting drugs.
— Correction of hypokalemia and hypomagnesemia (cautiously — if hyperkalemic, do not reflexively give K+).
— IV fluids for volume restoration if AKI is precipitant.
— Atropine for symptomatic bradycardia as a bridge.
— Activated charcoal if presenting within 1–2 hours of acute ingestion and airway protected; multi-dose charcoal can interrupt enterohepatic recirculation but evidence is modest.
Step 3 management: When in doubt, give Fab. It is exceptionally safe, rapidly effective (onset 20–30 min, full effect by 4 hours), and the threshold to administer is low — board questions almost always reward the test-taker who chooses Fab in the severely toxic patient over conservative management.
— Mechanism: ovine antibody Fab fragments bind free digoxin in serum, creating a concentration gradient that pulls digoxin out of tissues (including myocardium); the Fab-digoxin complex is renally excreted.
— Onset: clinical improvement in 20–30 minutes; complete effect by 4 hours.
— Each vial (40 mg) binds approximately 0.5 mg of digoxin.
— Known ingested dose (acute): Number of vials = (mg ingested × 0.8 bioavailability) / 0.5.
Example: 10 mg ingested → (10 × 0.8) / 0.5 = 16 vials.
— Known steady-state level (chronic or post-distribution acute): Number of vials = (serum digoxin ng/mL × weight kg) / 100.
Example: level 8, weight 70 kg → (8 × 70)/100 ≈ 6 vials.
— Unknown amount, acute life-threatening toxicity: empiric 10–20 vials (adults), 10 vials initially in children.
— Unknown amount, chronic toxicity, unstable adult: empiric 3–6 vials (lower because total body burden is smaller in chronic toxicity).
— Cardiac arrest: 20 vials IV push.
— Atropine 0.5–1 mg IV for symptomatic bradycardia/AV block as a bridge.
— Magnesium sulfate 2 g IV for ventricular arrhythmias, especially if hypomagnesemic.
— Lidocaine or phenytoin historically used for ventricular arrhythmias refractory to Fab — rarely needed in the Fab era.
— Avoid Class IA antiarrhythmics (quinidine, procainamide) — worsen AV block.
— Avoid IV calcium for hyperkalemia in digoxin toxicity (traditional teaching, board-correct answer).
Board pearl: Insulin/dextrose, bicarbonate, and Kayexalate are acceptable temporizing measures for hyperkalemia; calcium is the classic "wrong answer" — Fab itself corrects hyperkalemia within hours by restoring Na+/K+ ATPase function.
— Intubate if obtunded or unable to protect airway.
— Two large-bore IVs, continuous cardiac and pulse oximetry monitoring, defibrillator pads on if unstable arrhythmia.
— Atropine 0.5–1 mg IV every 3–5 min (max 3 mg) — often only transiently effective.
— Transcutaneous pacing as a bridge if Fab not immediately available.
— Transvenous pacing — use cautiously; mechanical irritation of the toxic myocardium can precipitate ventricular fibrillation. Fab is preferred over pacing when available.
— Avoid isoproterenol and dopamine when possible — pro-arrhythmic in the digitalized heart.
— Defibrillation for VF/pulseless VT — but use lower energies initially (50–100 J) if possible; toxic myocardium is electrically unstable and standard energies can produce refractory VF. Modern teaching often defers to standard ACLS energies, but the "lower energy first" concept remains board-relevant.
— Magnesium 2 g IV.
— Lidocaine 1–1.5 mg/kg IV for refractory VT.
— Fab is definitive.
— Activated charcoal 1 g/kg PO/NG within 1–2 hours of acute ingestion if airway protected.
— Multi-dose activated charcoal (25–50 g every 4 hours) may interrupt enterohepatic recirculation in massive ingestion.
— Avoid gastric lavage and ipecac — vagal stimulation worsens bradycardia.
— Replete magnesium liberally (2–4 g IV) unless renal failure.
— Potassium: repletion only if hypokalemic (chronic toxicity) and K+ <4.0; AVOID K+ supplementation in hyperkalemic acute toxicity.
— Correct volume status with isotonic fluids if AKI from dehydration.
CCS pearl: Order set for severe toxicity — DigiFab, atropine, magnesium IV, activated charcoal (if <2h and airway protected), cardiac monitor, two IVs, defibrillator at bedside, hold all AV nodal blockers, consult toxicology and cardiology, admit to ICU.
— Reduced lean body mass and renal function → higher serum levels for any given dose.
— Target dose 0.125 mg daily or every other day in most elderly HF patients; some experts avoid digoxin entirely in patients >80.
— Sarcopenia means standard weight-based dosing overshoots.
— Polypharmacy: common culprits raising levels include amiodarone, verapamil, diltiazem, quinidine, dronedarone, propafenone, spironolactone, clarithromycin, erythromycin, itraconazole, ketoconazole, cyclosporine (P-glycoprotein inhibitors).
— Concurrent loop diuretics → hypokalemia and hypomagnesemia → toxicity at "therapeutic" levels.
— Digoxin is 60–80% renally cleared as unchanged drug.
— In CKD stage 3–5, reduce dose by 25–75% and extend interval; many use 0.125 mg every 48 hours or avoid entirely.
— AKI is the most common precipitant of chronic toxicity — sick day rules should include holding digoxin during gastroenteritis or dehydration episodes.
— Hemodialysis does NOT remove digoxin (Vd 5–7 L/kg, highly tissue-bound).
— Fab-digoxin complex is renally cleared; in anuric/dialysis patients, rebound free digoxin toxicity can occur 24–72 hours after Fab as digoxin redistributes from tissues and Fab is not cleared — monitor longer and consider repeat dosing.
— Less impact than renal (digoxin is minimally hepatically metabolized), but altered volume of distribution and concurrent renal dysfunction (hepatorenal) warrant cautious dosing.
Step 3 management: When starting digoxin in an elderly HFrEF patient, dose 0.125 mg daily, check level at steady state (5–7 days), target 0.5–0.9 ng/mL, and counsel on sick day rules (hold for vomiting, diarrhea, or inability to take fluids). Review the medication list at every visit for new P-glycoprotein inhibitors.
Board pearl: Amiodarone roughly doubles digoxin levels — when adding amiodarone, empirically halve the digoxin dose and recheck level in one week.
— Digoxin is Category C but widely used — first-line for fetal supraventricular tachycardia and maternal arrhythmias including AFib in pregnancy.
— Crosses the placenta; fetal serum levels approach maternal.
— Endogenous digoxin-like immunoreactive substances (DLIS) are elevated in pregnancy, especially third trimester and preeclampsia — can cause false-positive low-level digoxin assays in pregnant women not taking digoxin.
— Fab is considered safe in pregnancy for life-threatening toxicity; benefits outweigh theoretical risks. Do not withhold for pregnancy alone.
— Acute ingestion of ≥4 mg or >0.1 mg/kg is potentially toxic; ≥0.3 mg/kg or level >5 ng/mL warrants Fab.
— Exploratory ingestions of grandparent's medications are classic.
— Pediatric Fab dosing same formula by weight; empiric 1–2 vials often sufficient for small ingestions.
— Neonatal DLIS can cause false-positive digoxin levels; correlate clinically.
— Foxglove, oleander, lily of the valley, yellow oleander tea (common in suicide attempts in South Asia), Bufo toad ("love stone," Chan Su, aphrodisiacs) → all respond to Fab, though sometimes higher doses required because immunoassay cross-reactivity is variable and total glycoside burden may exceed standard estimates.
— Empiric 10–20 vials for severe plant glycoside toxicity.
— Hawthorn, kyushin, and various traditional Chinese medicines may contain cardiac glycosides.
Key distinction: DLIS produces low-level false-positive digoxin readings in pregnancy, neonates, and renal/hepatic failure — never treat based on level alone; clinical picture must support toxicity.
Board pearl: Fetal SVT with hydrops is treated with maternal oral digoxin (sometimes with flecainide or sotalol) — a transplacental antiarrhythmic strategy. Maternal toxicity is the dose-limiting concern.
— Ventricular fibrillation, refractory ventricular tachycardia, asystole — leading causes of death.
— Complete heart block with inadequate escape rhythm.
— Cardiogenic shock from sustained bradyarrhythmia or pump failure exacerbation.
— Bidirectional VT progressing to VF.
— Post-Fab rebound HF or AFib with RVR — because the therapeutic effect of digoxin is also abolished; patients dependent on digoxin for rate control may develop rapid ventricular response in AFib.
— Hyperkalemia-induced arrhythmia in acute toxicity — independent mortality predictor; corrects with Fab.
— Hypokalemia from over-aggressive correction post-Fab.
— Rebound hyperkalemia or hypokalemia depending on initial state.
— Persistent delirium, especially in elderly with baseline cognitive impairment.
— Rare seizures.
— Visual symptoms typically resolve with toxicity resolution.
— Hypersensitivity reactions — anaphylaxis (~0.8%), serum sickness with repeated exposure or large doses (ovine protein). Prior allergy to sheep products, papain, or papaya is a relative contraindication — but in life-threatening toxicity, give anyway with epinephrine ready.
— Hypokalemia as K+ shifts intracellularly with restored ATPase function — monitor and replete.
— Worsening HF or rapid AFib from loss of digoxin effect.
— Rebound toxicity in renal failure as Fab-bound digoxin redistributes.
— Rare mesenteric ischemia from digoxin-induced splanchnic vasoconstriction in severe toxicity.
— Anoxic brain injury in cardiac arrest survivors.
— Psychiatric follow-up if intentional ingestion.
Step 3 management: After Fab administration, monitor K+, magnesium, and ECG every 2–4 hours initially, anticipate hypokalemia, and have a plan for managing the underlying indication (HF, AFib) without digoxin going forward.
Board pearl: Anaphylaxis to Fab is rare (<1%) and should not delay administration in life-threatening toxicity — have epinephrine, diphenhydramine, and resuscitation equipment at bedside.
— Any patient receiving Fab fragments.
— Hemodynamically unstable bradyarrhythmia or tachyarrhythmia.
— Hyperkalemia >5.5 or refractory to initial management.
— Altered mental status.
— Need for transcutaneous or transvenous pacing.
— Intentional overdose with co-ingestions, especially TCAs or beta-blockers.
— End-stage renal disease with toxicity (prolonged monitoring for rebound).
— Stable chronic toxicity with mild symptoms, normal hemodynamics, no significant arrhythmia, and modest level elevation after dose held.
— Post-Fab patients clinically stable for 24+ hours can transition.
— Medical toxicology / Poison Control (1-800-222-1222 in US) — call early; Fab dosing, indications, and procurement help.
— Cardiology — for arrhythmia management, pacing decisions, post-toxicity rhythm management, and reassessment of the indication for digoxin.
— Nephrology — if AKI requires dialysis (not for digoxin removal, but for uremia/volume).
— Psychiatry — for all intentional ingestions before discharge.
— Pharmacy — assist with Fab procurement (not stocked at all hospitals; may need to transfer or arrange shipment from regional center).
— Community hospitals without DigiFab on formulary should initiate transfer early to a tertiary center while stabilizing with atropine, pacing, and supportive care. Do not delay transfer awaiting Fab arrival if patient is unstable.
— Acceptable only for asymptomatic patients with inadvertent single missed-dose or minor accidental ingestion, normal ECG, normal K+, normal renal function, level not significantly elevated, and reliable follow-up within 24–48 hours.
CCS pearl: On a CCS case, call Poison Control AND admit to ICU for any patient receiving Fab — the simulator rewards appropriate consultation and disposition; do not "treat and discharge" Fab recipients.
— Foxglove (Digitalis purpurea, D. lanata) — direct source of digoxin/digitoxin; clinically identical.
— Oleander (Nerium oleander) and yellow oleander (Thevetia peruviana) — oleandrin; widespread in Sri Lanka/South Asia as suicide method. Fab effective but higher doses often needed.
— Lily of the valley (Convallaria majalis) — convallatoxin; pediatric exploratory ingestions.
— Red squill (Urginea maritima) — historically a rodenticide.
— Bufo toad venom (Bufo marinus, B. alvarius) — bufadienolides; ingested as aphrodisiacs ("Love Stone," "Chan Su").
— Hawthorn, kyushin, lily-of-the-valley tea — herbal preparations.
— Beta-blocker toxicity — bradycardia, hypotension, hypoglycemia, bronchospasm, normal K+ usually. Treat with glucagon, high-dose insulin/euglycemia, calcium, lipid emulsion.
— Calcium channel blocker toxicity — bradycardia, hypotension, hyperglycemia (especially non-dihydropyridines like verapamil/diltiazem). Treat with calcium, high-dose insulin, vasopressors, lipid emulsion.
— Clonidine/alpha-2 agonist overdose — bradycardia, hypotension, miosis, CNS depression mimicking opioid toxicity.
— Organophosphate poisoning — bradycardia plus SLUDGE/DUMBELS cholinergic toxidrome.
— Digoxin: GI symptoms + visual changes + hyperkalemia (acute) + characteristic arrhythmias (bidirectional VT, AT with block, regularized AFib).
— BB: hypoglycemia, no visual changes, no characteristic ECG signature.
— CCB: hyperglycemia, profound vasoplegia.
— Clonidine: miosis, opioid-like presentation, responds to naloxone variably.
Key distinction: Hyperkalemia + bradycardia + GI symptoms + visual changes = digoxin until proven otherwise; hyperglycemia + bradycardia + hypotension = CCB; hypoglycemia + bradycardia + bronchospasm = beta-blocker.
— Inferior MI can present with bradycardia, hypotension, nausea, vomiting — overlapping presentation with digoxin toxicity in an elderly patient on digoxin.
— Differentiate with troponin, serial ECGs for ST elevation, coronary angiography if indicated.
— The two can coexist; ACS can precipitate digoxin toxicity via AKI/hypoperfusion.
— Elderly patient with sinus pauses, bradycardia, syncope — may be misattributed to digoxin if level is therapeutic.
— Pacemaker evaluation after toxicity workup is negative.
— AKI, rhabdomyolysis, adrenal insufficiency, ACEi/ARB/spironolactone use.
— Without digoxin exposure, hyperkalemia produces peaked T waves, widened QRS, sine wave — different ECG signature.
— The most common misdiagnosis in chronic digoxin toxicity. Always check level in any digoxin user with GI symptoms.
— Elderly chronic toxicity often misdiagnosed; routine inclusion of digoxin level in delirium workup of digoxin users is essential.
— Visual disturbances and confusion may prompt stroke workup; check digoxin level concurrently.
— Bradycardia, fatigue, confusion. Also reduces digoxin clearance.
— Multi-organ dysfunction, AKI, can precipitate chronic toxicity in digoxin users.
— Amiodarone (bradycardia, AV block, plus pulmonary/thyroid/hepatic toxicity).
— Class I antiarrhythmics (QRS widening dominant).
Board pearl: In any elderly patient on digoxin presenting with nonspecific symptoms — GI, neurologic, or cardiac — a digoxin level + BMP is part of the minimum workup, alongside the more obvious differential considerations. Missing chronic digoxin toxicity in a "gastroenteritis" or "dementia" stem is a classic board trap.
— HFrEF: digoxin reduces hospitalizations but not mortality (DIG trial); modern HF therapy (ARNI, beta-blocker, MRA, SGLT2 inhibitor) is far superior. Many patients can discontinue digoxin after toxicity event.
— AFib rate control: digoxin is now second-line behind beta-blockers and non-dihydropyridine CCBs; associated with increased mortality in observational studies (especially at levels >1.2). Switch to beta-blocker preferentially.
— Document a deliberate decision to resume vs discontinue, with rationale.
— Dose 0.125 mg daily or every other day in elderly/renal impairment.
— Target level 0.5–0.9 ng/mL for HF.
— Steady-state level check 5–7 days after any dose change or interacting drug addition.
— Annual level if stable; sooner with any clinical change.
— Avoid or reduce digoxin dose with amiodarone, dronedarone, verapamil, diltiazem, quinidine, propafenone, spironolactone, clarithromycin, erythromycin, azole antifungals, cyclosporine, ranolazine.
— Educate patient to inform all prescribers of digoxin use.
— Hold digoxin (and ACEi/ARB, diuretics, metformin, NSAIDs) during acute illness with vomiting, diarrhea, or poor PO intake.
— Resume after rehydration and clinical recovery.
— Maintain K+ 4.0–5.0 and Mg 2.0+ in digoxin users on diuretics.
— Consider potassium-sparing strategies (MRA) when appropriate for HF.
— Recognize warning symptoms: visual changes, nausea, palpitations, confusion.
— Medication list card; pharmacist medication reconciliation at every transition of care.
Step 3 management: After a digoxin toxicity event, switch HF patients to optimized GDMT (ARNI/BB/MRA/SGLT2i) and AFib patients to beta-blocker for rate control; resume digoxin only if symptomatic refractoriness despite optimized therapy, with thorough counseling and the lowest effective dose.
— Continuous telemetry for at least 24 hours after clinical resolution; longer (48–72 hours) in renal impairment due to rebound risk.
— Serial K+, Mg, creatinine every 4–6 hours initially.
— Do not trend total digoxin levels post-Fab — uninterpretable.
— Reassess hemodynamics, symptoms, and underlying disease (HF, AFib).
— Stable rhythm off pacing for ≥24 hours.
— Normal or normalized K+ and Mg.
— Mental status returned to baseline.
— Underlying precipitant addressed (AKI improving, interacting drug stopped/adjusted).
— Reliable outpatient follow-up arranged.
— Primary care or cardiology visit within 1–2 weeks post-discharge.
— BMP and digoxin level (if resumed) at 1 week.
— Medication reconciliation by pharmacist before discharge and at first follow-up.
— Repeat ECG in 1–2 weeks; echocardiogram if not recent or if new arrhythmia.
— Sick day rules — written instructions for holding digoxin during illness.
— Drug interaction list — patient-held card.
— Warning symptoms to prompt ED return: nausea/vomiting >24 hours, visual changes, palpitations, syncope, confusion.
— Pillbox use, single pharmacy, medication adherence aids — especially elderly.
— Caregiver involvement in medication management when cognition is borderline.
— All intentional ingestions require psychiatric assessment before discharge and outpatient mental health linkage within 1 week.
— Update problem list with "digoxin toxicity" so future prescribers see history.
— Communicate event to primary care via secure message/discharge summary.
CCS pearl: Schedule a 2-week post-discharge follow-up with labs (BMP, Mg, digoxin level if resumed) and medication reconciliation — the CCS simulator and the boards reward explicit attention to transitions of care after high-risk medication events.
— Fab is derived from sheep; allergic patients (papain, papaya, prior Fab exposure) should be counseled on anaphylaxis risk.
— In life-threatening toxicity with altered mental status, implied consent (emergency exception) applies — proceed without delay, document clinical necessity, attempt to reach surrogate concurrently.
— Cost: Fab is expensive (~$3000–4000 per vial; full course can exceed $40,000). This should not delay administration but is a relevant counseling and systems issue.
— Safety planning, lethal means restriction, psychiatric admission for high-risk patients.
— Document capacity assessment; involuntary hold (Section 12, 5150, etc., by jurisdiction) may be required.
— Remove access to remaining digoxin and other medications at home — counsel family.
— Pediatric exploratory ingestion → assess for neglect/inadequate supervision; mandatory child protective services report if suspicion of neglect or unsafe storage repeatedly.
— Elder self-neglect or possible caregiver medication error → adult protective services in many jurisdictions.
— Medication reconciliation errors are the leading cause of digoxin toxicity in transitions (hospital → SNF → home). Always reconcile digoxin dose, renal function, and interacting drugs at every transition.
— Discharge medication lists should explicitly note digoxin dose, level target, and sick day rules.
— Closed-loop communication with the receiving facility/PCP within 48 hours.
— Avoid digoxin initiation in patients with eGFR <30 without strong indication.
— Use clinical decision support / EHR alerts for digoxin + amiodarone, digoxin + verapamil, etc.
— Brown bag medication review at every primary care visit for elderly patients on digoxin.
— If toxicity resulted from a prescribing or dispensing error, transparent disclosure to patient/family is ethically and (in many states) legally required; institutional patient safety/risk management notification per policy.
Board pearl: A discharge stem where a patient on digoxin is sent to a SNF without medication reconciliation and returns with toxicity is a patient safety / transition-of-care failure — the correct answer is typically structured medication reconciliation and communication with the receiving provider.
— Atrial tachycardia with AV block (PAT with block) — classic.
— Bidirectional VT.
— Junctional rhythms, accelerated junctional tachycardia.
— Regularized ventricular response in AFib.
— "Salvador Dalí mustache" scooped ST depression = effect, not toxicity.
Board pearl: Memorize the triad of bidirectional VT + hyperkalemia + GI symptoms = acute digoxin toxicity. Memorize regularized AFib + visual halos + elderly on diuretics = chronic digoxin toxicity.
— 78-year-old woman with HFrEF on digoxin, furosemide, lisinopril, and recently started clarithromycin for sinusitis presents with nausea, anorexia, and yellow halos. ECG: AT with 2:1 AV block. K+ 3.2, Cr 1.8 (baseline 1.1).
— Answer: Hold digoxin, replete K+ and Mg, consider Fab if hemodynamically unstable or arrhythmia worsens; discontinue clarithromycin.
— 22-year-old man ingests his grandmother's digoxin bottle (~30 tablets of 0.25 mg). Presents 4 hours later with vomiting, bradycardia 38, K+ 6.4, level 9 ng/mL (drawn at 4h, pre-distribution).
— Answer: Digoxin-specific Fab fragments empirically 10–20 vials; activated charcoal if airway secure; do NOT give IV calcium for hyperkalemia.
— Child from rural area presents with vomiting and bradycardia after ingesting "lily of the valley" berries. ECG with high-grade AV block.
— Answer: Fab fragments — effective for all cardiac glycosides, not just digoxin.
— After Fab administration, patient's digoxin level is reported as 28 ng/mL. Clinically improved, normokalemic, normal rhythm.
— Answer: No additional Fab needed; post-Fab total levels are uninterpretable.
— Patient on digoxin presents with wide-complex tachycardia with beat-to-beat axis alternation.
— Answer: Bidirectional VT — pathognomonic for digoxin toxicity; give Fab.
— Stable HF patient on digoxin develops new AFib, started on amiodarone. Two weeks later: nausea, confusion, bradycardia.
— Answer: Amiodarone doubled digoxin level; hold both, check level, supportive care vs Fab based on severity.
— Acute digoxin overdose with K+ 6.2 — best treatment?
— Answer: Fab fragments. Avoid IV calcium (classic distractor).
— 32-week pregnant woman with fetal SVT treated with maternal digoxin develops symptoms of toxicity.
— Answer: Fab is safe and indicated in pregnancy for serious maternal toxicity.
Board pearl: When the stem mentions yellow halos, bidirectional VT, regularized AFib, or PAT with block — the diagnosis is digoxin toxicity regardless of other distractors.
Digoxin toxicity is recognized by GI symptoms, visual halos, characteristic arrhythmias (AT with block, bidirectional VT, regularized AFib), and — in acute overdose — hyperkalemia, and is treated definitively with digoxin-specific Fab fragments dosed by ingested amount, serum level, or empirically (10–20 vials acute, 3–6 chronic, 20 cardiac arrest), with attention to magnesium repletion, avoidance of IV calcium, and recognition that hemodialysis is ineffective.
Board pearl: "Yellow halos + elderly + diuretic + new arrhythmia" = check the digoxin level before anything else — and remember Fab corrects hyperkalemia faster and more safely than insulin/glucose/calcium ever could.