Tetracycline and Digoxin: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Tetracycline
Digoxin
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
Increased digoxin exposure
Interaction Deep Dive
Concomitant use of tetracycline and digoxin may increase digoxin exposure12. In approximately 10% of patients, digoxin is converted to cardio-inactive metabolites by colonic bacteria within the gut. In these patients the coadministration of digoxin with tetracycline inhibits this metabolism and results in a significant increase in serum digoxin exposure 3. Measure digoxin exposure before initiating tetracycline. Reduce digoxin concentrations by decreasing dose by approximately 30-50% or by modifying the dosing frequency and continue monitoring. Also, monitor potential signs and symptoms of clinical toxicity is necessary when initiating, adjusting, or discontinuing tetracycline 12.
Why it happens (mechanism)
Unknown
Literature reports
2 reports — tap to read
a) In pharmacokinetic studies, concomitant administration of tetracycline and digoxin increased digoxin serum concentrations 100% 12.
b) Approximately 10% of patients receiving digoxin convert the drug to cardio-inactive metabolites. This inactivation may be attributed to gastrointestinal bacteria. Antibiotic therapy introduced to patients on digoxin has caused a marked decrease in digoxin reduction products and a marked rise in digoxin absorption and serum levels. It is concluded that changes in the enteric flora via antibiotics may alter the state of digitalization. Elevated serum digoxin concentrations by as much as 43% to 116% were observed after a 5-day course of tetracycline in 3 volunteers who produced large amounts of digoxin reduction products 3.
Common questions
Can I take Tetracycline and Digoxin together?
Increased digoxin exposure Always confirm with your pharmacist or prescriber before making any change.
How serious is the Tetracycline and Digoxin interaction?
It is rated major. Potentially serious — often needs a change or close 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 Tetracycline or Digoxin 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 a safer alternative to one of these medications for me?
References (3)
- Product Information: LANOXIN(R) oral tablets, digoxin oral tablets. Concordia Pharmaceuticals Inc (per FDA), Kansas City, MO, 2019. DailyMed
- Product Information: DIGOXIN oral tablets, digoxin oral tablets. Aurobindo Pharma USA, Inc. (per Dailymed), East Windsor, NJ, May. DailyMed
- Lindenbaum J, Rund DG, Butler VP, et al: Inactivation of digoxin by the gut flora: reversal by antibiotic therapy. N Engl J Med 1981a; 305:789-794. PubMed
Keep reading about Tetracycline
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.
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