Digoxin and Cascara Sagrada: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Digoxin
Cascara Sagrada
No brand names on record
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
Hypokalemia secondary to cascara sagrada bark intake, which may increase the risk of digoxin toxicity
Interaction Deep Dive
Cascara sagrada bark is noted in the German Commission E Monographs to be associated with potassium loss4. As with other plant anthranoid laxative sources, loss of potassium can occur secondary to excessive or prolonged use, termed "laxative abuse" 41. Potassium loss is partly due to direct loss in the feces and partly as secondary renal effect associated with sodium loss 1. Patients taking cascara sagrada bark for more than 1-2 weeks may experience hypokalemia (signs and symptoms include lethargy, muscle cramps, headaches, paresthesias, tetany, peripheral edema, polyuria, breathlessness, and hypertension). Hypokalemia may increase the risk of digoxin toxicity (signs and symptoms include anorexia, nausea, vomiting, diarrhea, weakness, visual disturbances, ventricular tachycardia). Concomitant use of cascara sagrada and digoxin should be avoided.
Why it happens (mechanism)
Hypokalemia caused by cascara sagrada
Literature reports
3 reports — tap to read
a) Laxative abuse using plants such as cascara sagrada bark that contain anthraquinone glycosides can lead to depletion of 25-50% of body potassium due to water and electrolyte losses 1.
b) Diuretic and digoxin maintenance therapy in 12 congestive heart failure patients studied for hypokalemia and cardiac arrhythmias resulted in digoxin toxicity in 6 patients with normal serum digoxin levels. The daily digoxin dose was 0.30 +/- 0.06 milligrams (mg) orally, and the mean serum concentration was 1.52 +/- 0.17 nanomoles/milliliter (nmol/mL). The mean serum potassium level was 3.41 +/- 0.09 millimoles/liter (mmol/L) for the 12 subjects 2.
c) Of 79 men with arrhythmias associated with digoxin intoxication, 24 were hypokalemic and 55 were normokalemic. In the hypokalemic group, mean serum potassium was 3 milliequivalents/liter (mEq/L) and mean serum digoxin level was 1.1 nanograms/milliliter (ng/mL) compared to 4.7 mEq/L potassium and 3.7 ng/mL digoxin in the normokalemic group 3.
Common questions
Can I take Digoxin and Cascara Sagrada together?
Hypokalemia secondary to cascara sagrada bark intake, which may increase the risk of digoxin toxicity Always confirm with your pharmacist or prescriber before making any change.
How serious is the Digoxin and Cascara Sagrada interaction?
It is rated moderate. Can be significant — usually manageable with monitoring.
How quickly could this interaction happen?
The documented onset is "delayed". Effects tend to build up gradually over days to weeks.
How strong is the evidence for this interaction?
The evidence is graded "probable". Good supporting evidence, though not definitively proven.
Questions for your pharmacist
- Does my dose of Digoxin or Cascara Sagrada need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there anything you'd monitor while I'm on both?
References (4)
- Westendorff J: Anthranoid derivatives - general discussion. DeSmet PAGM, Keller K, Hansel R et al (eds). Adverse Effects of Herbal Drugs, 2nd vol. Springer-Verlag, Berlin:105-118, 1993. DOI
- Steiness E & Olesen KH: Cardiac arrhythmias induced by hypokalaemia and potassium loss during maintenance digoxin therapy. Br Heart J 1976; 38:167-172. PubMed
- Shapiro W & Taubert K: Letter: Hypokalaemia and digoxin-induced arrhythmias. Lancet 1975; 2(7935):604-5.
- Blumenthal M, Busse WR, Goldberg A, et alBlumenthal M, Busse WR, Goldberg A, et al (Eds): The Complete German Commission E Monographs, 1st. American Botanical Council, Austin, TX, 1998, pp 80-81.
Keep reading about Digoxin
These medications also interact with supplements
Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
Check another combination
Our instant two-drug interaction checker is almost here.
Still have questions about this combination?
Every question gets a real answer from a licensed pharmacist — free, and usually within a day.
Ask the pharmacist