Digoxin: Pulse Checks, Toxicity Signs, and Potassium Safety
Teach the client to count the apical or radial pulse for 1 full minute before each dose, and to hold the dose and call the provider when the rate is under 60/min, unless the provider sets another limit. The therapeutic serum level is 0.5 to 2.0 ng/mL; many clients with heart failure are kept at 0.5 to 0.9 ng/mL. Hypokalemia increases the risk of toxicity.
Who needs this teaching
Clients who take digoxin for heart failure with reduced ejection fraction or for ventricular rate control in atrial fibrillation, and the caregiver. Digoxin has a narrow therapeutic range. The kidneys excrete digoxin, so older adults and clients with renal impairment have a higher risk of toxicity.
The priority teaching points
- Pulse before each dose. Count the apical or radial pulse for 1 full minute before each dose. Record the rate and rhythm. Hold the dose and call the provider when the rate is under 60/min in an adult, or below the limit the provider sets. Report a new irregular rhythm.
- Consistent dosing. Take digoxin once daily at the same time. Never double a dose to make up for a missed dose; follow the provider's missed-dose instructions. Use a pill organizer or calendar to prevent accidental extra doses.
- Toxicity signs. Early signs are anorexia, nausea, and vomiting. Other signs are blurred vision, yellow-green vision or halos around lights, confusion, fatigue, bradycardia, and new dysrhythmias. Older adults frequently present with confusion. Hold the dose and report any sign the same day.
- Potassium. Hypokalemia increases the risk of digoxin toxicity. Loop and thiazide diuretics cause potassium loss. Take prescribed potassium supplements. Report vomiting, diarrhea, or poor intake. Normal serum potassium is 3.5 to 5.0 mEq/L. Hypomagnesemia, hypercalcemia, and declining renal function also increase toxicity risk.
- Blood level monitoring. The therapeutic serum digoxin level is 0.5 to 2.0 ng/mL. Many clients with heart failure are kept at 0.5 to 0.9 ng/mL. Draw the sample at least 6 hours after the last dose, usually just before the next dose. Keep appointments for potassium and serum creatinine checks.
- Interactions. Antacids reduce digoxin absorption; separate them by at least 2 hours, or as the pharmacist directs. Amiodarone and verapamil increase serum digoxin levels; the prescriber reduces the digoxin dose and checks the level. St. John's wort decreases digoxin levels. Review every new prescription, nonprescription product, and supplement with the pharmacist.
- Overdose. For extra tablets taken without symptoms, call Poison Control (1-800-222-1222 in the US) or the local poison center. Call 911 for syncope or a very slow or very fast pulse with symptoms.
Red flags the client reports
| Call the provider the same day | Call 911 or the local emergency number |
|---|---|
| Pulse under 60/min or below the prescribed limit (dose held) | Syncope or near-syncope |
| Anorexia, nausea, or vomiting | Very slow or very fast pulse with chest pain, dizziness, or shortness of breath |
| Blurred vision, yellow-green vision, or halos around lights | Severe confusion or sudden change in mental status |
| New irregular pulse, unusual fatigue, or mild confusion | Extra doses taken with any symptoms |
| Vomiting or diarrhea during diuretic therapy | Severe shortness of breath at rest |
Teach-back questions
- "Show me how you count your pulse before your dose."
- "What pulse rate means you hold the dose and call?"
- "Name three signs of too much digoxin."
- "Why does your water pill matter for digoxin safety?"
- "What will you do if you miss a dose?"
Teaching tips
- Observe a full return demonstration of the 1-minute pulse count with a watch that shows seconds.
- Write the client's pulse limit on the handout.
- Include the caregiver, because confusion is a toxicity sign.
- Review the medication list for diuretics, amiodarone, verapamil, and supplements.
Read more on NCLEXPace
- Cardiac Drugs on the NCLEX: Digoxin, ACE Inhibitors and Nitrates
- Therapeutic Drug Levels: The Four You Must Know
- Potassium on the NCLEX: Why K+ Is the Exam's Favourite Electrolyte
Sources
- Harding MM, Kwong J, Hagler D, Reinisch C. Lewis's Medical-Surgical Nursing: Assessment and Management of Clinical Problems. 12th ed. Elsevier; 2023; Chapters: Heart Failure; Dysrhythmias.
- Digoxin Tablets: FDA prescribing information (DailyMed).
- Heidenreich PA, et al. 2022 AHA/ACC/HFSA Guideline for the Management of Heart Failure. Circulation. 2022;145(18):e895-e1032.
Why this matters for the NCLEX
Teaching is effective when the client states, "I count my pulse for a full minute before each dose and call if it is under 60," and "I will report nausea or yellow vision." Statements requiring further teaching include, "I will take two tablets tomorrow if I forget today," "Nausea is a normal effect, so I keep taking it," and "My water pill has nothing to do with digoxin."
Frequently asked questions
Why does the client report vomiting or diarrhea while taking digoxin and a diuretic?
Fluid losses lower serum potassium. Hypokalemia increases the risk of digoxin toxicity.
Does a serum level inside 0.5 to 2.0 ng/mL rule out toxicity?
No. Toxicity occurs within the therapeutic range, especially with hypokalemia. Clinical signs require assessment at any level.
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