Also indexed as: Lanoxicaps, Lanoxin
Digoxin is a drug originally derived from the foxglove plant, Digitalis lanata.
Digoxin is used primarily to improve the pumping ability of the heart in congestive heart failure (CHF). It is also used to
help normalize some dysrhythmias (abnormal types of heartbeat).
Summary of
Interactions with Vitamins, Herbs, and Foods
In some cases, an herb or supplement may appear in more than one category, which may seem
contradictory. For clarification, read the full article for details about the summarized
interactions.
 May Be Beneficial: Depletion or
interference—The medication may deplete or interfere with the absorption or
function of the nutrient. Taking these nutrients may help replenish them. |
Magnesium
Potassium (if levels are low)
|
| May Be Beneficial: Side effect
reduction/prevention—Taking these supplements may help reduce the likelihood and/or
severity of a potential side effect caused by the medication. |
Magnesium
Potassium
|
Avoid: Reduced drug absorption/bioavailability—Avoid these supplements
when taking this medication since the supplement may decrease the absorption and/or activity
of the medication in the body. |
Senna*
St. John’s wort*
|
|
Avoid: Adverse interaction—Avoid these supplements when taking this
medication because taking them together may cause undesirable or dangerous results. |
Cascara*
Digitalis
Eleuthero*
Licorice*
Pleurisy root
Sarsaparilla
Senna*
|
Check: Other—Before taking any of these supplements or eating any of
these foods with your medication, read this article in full for details. |
Alder buckthorn*
Buckthorn*
Hawthorn
Potassium*
|
| Supportive interaction |
None known
|
An asterisk (*) next to an item in the summary indicates that the
interaction is supported only by weak, fragmentary, and/or contradictory scientific
evidence.
Interactions with Dietary Supplements
Magnesium
People needing digoxin may have low levels of potassium or magnesium,1 increasing
the risk for digoxin toxicity. Digoxin therapy may increase magnesium elimination from the
body.2 People taking digoxin may benefit from magnesium
supplementation.3 Medical doctors do not commonly check magnesium status, and when
they do, they typically use an insensitive indicator of magnesium status (serum or plasma
levels). The red blood cell magnesium level may be a more sensitive indicator of magnesium
status, although evidence is conflicting. It has been suggested that 300–500 mg of
magnesium per day is a reasonable amount to supplement.4
Potassium
Medical doctors prescribing digoxin also check for potassium depletion and prescribe potassium
supplements if needed. Potassium transport from the blood into cells is impaired by
digoxin.5 Although digoxin therapy does not usually lead to excess potassium in the
blood (hyperkalemia), an overdose of digoxin could cause a potentially fatal
hyperkalemia.6 People taking digoxin should therefore avoid taking potassium
supplements, or eating large quantities of
fruit (e.g., bananas), unless directed to
do so by their doctor. On the other hand, many people taking digoxin are also taking a diuretic; in these individuals, increased intake
of potassium may be needed. These issues should be discussed with a doctor.
Interactions with Herbs
Alder Buckthorn,
Buckthorn(Rhamnus catartica, Rhamnus
frangula, Frangula alnus)
Use of buckthorn or alder buckthorn for more than ten days consecutively may cause a loss of
electrolytes (especially the mineral potassium). Loss of potassium may increase the toxicity
of digitalis-like medications with potentially fatal consequences.7
Cascara
(Rhamnus purshiani cortex)
Loss of potassium due to cascara abuse could
theoretically increase the effects of digoxin and other similar heart medications, with
potentially fatal consequences. However, no cases of such an interaction have yet been
reported.
Digitalis (Digitalis purpurea)
Digitalis refers to a group of plants commonly called foxglove that contain chemicals with
actions and toxicities similar to digoxin. Digitalis was used as an herbal medicine to treat
some heart conditions before the drug digoxin was available. Some doctors continue to use
digitalis in the United States, and it is used as an herbal medicine in other countries as
well. Due to the additive risk of toxicity, digitalis and digoxin should never be used
together.
Eleuthero (Eleutherococcus senticosus)
People taking digoxin require regular monitoring of serum digoxin levels. In one report,
addition of a product identified as Siberian ginseng to stable, therapeutic digoxin treatment
was associated with dangerously high serum digoxin levels.8 The patient never
experienced symptoms of digoxin toxicity. Laboratory analysis found the product was free of
digoxin-like compounds but the contents were not further identified. This report may reflect
an interaction of eleuthero with the laboratory test to cause a falsely elevated reading,
rather than actually increasing digoxin levels.
Hawthorn (Crataegus oxyacantha, Crataegus monogyna)
Hawthorn (leaf with flower) extract is approved in Germany to treat mild congestive heart failure.9 Congestive heart
failure is a serious medical condition that requires expert medical management rather than
self-treatment. Due to the narrow safety index of digoxin, it makes sense for people taking
digoxin for congestive heart failure to consult with their doctor before using
hawthorn-containing products. Reports of hawthorn interacting with digitalis to enhance its
effects have not been confirmed.
Licorice (Glycyrrhiza glabra)
Potassium deficiency increases the risk of
digoxin toxicity. Excessive use of licorice plant or licorice plant products may cause the
body to lose potassium.10 Artificial licorice flavoring does not cause potassium
loss. People taking digoxin should read product labels carefully for licorice plant
ingredients.
Pleurisy
root
As pleurisy root and other plants in the Aesclepius genus contain cardiac glycosides,
it is best to avoid use of pleurisy root with heart medications such as
digoxin.11
Sarsaparilla (Smilax spp.)
Sarsaparilla may increase the absorption of digitalis and bismuth, increasing the chance of
toxicity.12
Senna
(Cassia senna, Cassia angustifolia)
Bisacodyl, a laxative similar in action to
senna, given with digoxin decreased serum digoxin levels in healthy volunteers compared with
digoxin alone.13 In patients taking digoxin, laxative use was also associated with
decreased digoxin levels.14 In addition, concern has been expressed that overuse or
misuse of senna may deplete potassium levels
and increase both digoxin activity and risk of toxicity.15 However, overuse of
senna could also decrease digoxin activity because, as noted, laxatives can decrease the
levels of the drug.
St. John’s
wort (Hypericum perforatum)
One preliminary trial has suggested that St. John’s wort may reduce blood levels of
digoxin.16 In this study, healthy volunteers took digoxin for five days, after
which they added 900 mg per day of St. John’s wort while continuing the daily digoxin. A
normal blood level of digoxin was reached after five days of taking the drug, but this level
dropped significantly when St. John’s wort was added. This may have occurred because
certain chemicals found in St. John’s wort activate liver enzymes that are involved in
the elimination of some drugs.17 18 Until more is known, people taking
digoxin should avoid St. John’s wort.
Interactions with Foods and Other Compounds
Food
Many foods may interfere with the absorption of digoxin. To avoid this problem, people should
take digoxin one hour before or two hours after eating food.19 People taking
digoxin should consult their prescribing doctor or pharmacist if they have questions regarding
this interaction.
References:1. Whang R, Oei TO, Watanabe A. Frequency of hypomagnesiumia in
hospitalized patients receiving digitalis. Arch Intern Med 1985;145:655–6.
2. Holt GA. Food & Drug Interactions. Chicago: Precept
Press, 1998, 94.
3. Landauer RA. Magnesium deficiency and digitalis toxicity.
JAMA 1984;251:730 [letter/review].
4. Cohen L, Kitzes R. Letter. JAMA 1984;251:730.
5. Lown B, Black H, Moore FD. Digitalis, electrolytes and the surgical
patient. Am J Cardiol 1960;6:309–37.
6. Smith TW, Willerson JT. Suicidal and accidental digoxin ingestion.
Report of five cases with serum digoxin level correlations. Circulation
1971;44:29–36.
7. European Scientific Cooperative on Phytotherapy (ESCOP). Frangulae
cortex, frangula bark. Monographs on the Medicinal Uses of Plant Drugs. Exeter, UK:
University of Exeter, Centre for Complementary Health Studies, 1997.
8. McRae S. Elevated serum digoxin levels in a patient taking digoxin and
Siberian ginseng. Can Med Assoc J 1996;155:293–5.
9. Blumenthal M, ed. The Complete German Commission E
Monographs. Austin, TX: American Botanical Council, 1998, 143.
10. Tyler VE. The Honest Herbal, 3rd ed. New York:
Pharmaceutical Products Press, 1993, 198.
11. Newall CA, Anderson LA, Phillipson JD. Herbal Medicines: A Guide
for Health-Care Professionals. London: Pharmaceutical Press, 1996, 213–4.
12. Bradley PR (ed). British Herbal Compendium, vol 1.
Bournemouth, Dorset, UK: British Herbal Medicine Association, 1992, 194–6.
13. Wang DJ, Chu KM, Chen JD, et al. Drug interaction between digoxin and
bisacodyl. J Formos Med Assoc 1990;89:913, 915–9 [in Chinese].
14. Botzler R, Ritter U. Effect of laxative measures on the serum
concentration of digoxin in the human. Leber Magen Darm Nov 1982; 14(6):255–7
[in German].
15. Newall CA, Anderson LA, Phillipson JD. Herbal Medicines: A Guide
for Healthcare Professionals. London: Pharmaceutical Press, 1996, 244.
16. Johne A, Brockmöller, Bauer S, et al. Pharmacokinetic
interaction of digoxin with an herbal extract from St. John’s wort (Hypericum
perforatum). Clin Pharmacol Ther 1999;66:338–45.
17. Nebel A, Schneider BJ, Baker RK, Kroll DJ. Potential metabolic
interaction between St. John’s wortand theophylline [letter]. Ann Pharmacother
1999;33:502.
18. Mai I, Schmider J, et al. Unpublished results, May, 1999. Reported
in: Johne A, Brockmöller, Bauer S, et al. Pharmacokinetic interaction of digoxin with an
herbal extract from St. John’s wort (Hypericum perforatum). Clin Pharmacol
Ther 1999;66:338–45.
19. Holt GA. Food & Drug Interactions. Chicago: Precept
Press, 1998, 93.