Quinine and Digoxin: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Quinine
No brand names on recordDigoxin
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
Coadministration of digoxin and quiNINE (P-gp inhibitor) may increase digoxin exposure. Measure digoxin exposure before initiating concomitant drugs. Reduce digoxin concentrations by decreasing the dose by approximately 15-30% 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 quiNINE1243.
Why it happens (mechanism)
Inhibition of P-gp mediated efflux transport of digoxin
Literature reports
4 reports — tap to read
a) In pharmacokinetic studies, concomitant use of quiNINE and digoxin increased digoxin AUC by 33% 12. Concomitant administration of quiNINE and IV digoxin increased digoxin AUC by 34% to 38% 43.
b) Since quiNINE is the levorotory stereoisomer of quiNIDine, its interaction with digoxin has been studied. The results indicate that the effect of quiNIDine on digoxin renal clearance is non-stereospecific. QuiNIDine and quiNINE may have the same effect on digoxin by inhibiting the tubular secretion and thus decreasing renal clearance of digoxin 5. QuiNINE has also been shown to decrease biliary secretory clearance of digoxin 6.
c) The effect of quiNINE on the pharmacokinetics of digoxin was studied in 7 healthy male volunteers. Each subject received an oral loading dose of digoxin 1 mg over a 24-hour period, followed by an oral maintenance dose of 0.1875 mg twice daily. After 2 weeks of digoxin therapy, quiNINE sulfate 250 mg once daily was initiated for a 1 week period. The quiNINE dose was then increased to 750 mg daily for an additional week. Results showed that quiNINE increased the digoxin plasma concentration from 0.64 nanogram/mL (ng/mL; 0.82 nanomol/L) prior to quiNINE therapy to 0.8 ng/mL (1.02 nanomol/L) during quiNINE 250 mg administration and 0.85 ng/mL (1.088 nanomol/L) during quiNINE 750 mg administration. The renal clearance of digoxin fell from 181 mL/min during control to 174 mL/min during quiNINE 250 mg treatment and 171 mL/min during quiNINE 750 mg treatment. CrCl and renal digoxin clearance were not altered during quiNINE and digoxin coadministration 7.
d) Six subjects (four healthy and two hospitalized) were given an IV dose of digoxin 1 mg over 10 minutes. Four days later, quiNINE sulfate 200 mg every eight hours was administered for 4 days before and 4 days after a second dose of IV digoxin 1 mg. QuiNINE decreased the digoxin total body clearance by 26% (from 2.98 mL/min/kg to 2.22 mL/min/kg). The half-life of digoxin was increased from 34.2 hours to 51.8 hours, representing a 32% decrease in the digoxin elimination rate constant. Digoxin Vd and renal clearance were unaltered. These results suggest that quiNINE alters the metabolism or biliary secretion of digoxin, thereby reducing digoxin total body clearance 8.
Common questions
Can I take Quinine and Digoxin together?
Increased digoxin exposure Always confirm with your pharmacist or prescriber before making any change.
How serious is the Quinine 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 "unspecified". The timing of this interaction is not well characterized.
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 Quinine 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 (8)
- 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
- Product Information: DIGOXIN intravenous injection, digoxin intravenous injection. Hikma Pharmaceuticals USA Inc. (per Dailymed), Berkeley Heights, NJ, 2023. DailyMed
- Product Information: LANOXIN® intravenous, intramuscular injection, digoxin intravenous, intramuscular injection. Covis Pharma (per FDA), King of Prussia, PA, 2025. DailyMed
- Aronson JK & Carver JG: Interaction of digoxin with quinine (letter). Lancet 1981; 1:1418. PubMed
- Hedman A: Inhibition by basic drugs of digoxin secretion into human bile. Eur J Clin Pharmacol 1992; 42:457-459. DOI
- Pedersen KE, Madsen JL, Klitgaard NA, et al: Effect of quinine on plasma digoxin concentration and renal digoxin clearance. Acta Med Scand 1985; 218:229-232. PubMed
- Wandell M, Powell JR, Hager WD, et al: Effect of quinine on digoxin kinetics. Clin Pharmacol Ther 1980; 28:425-430. DOI
Keep reading about Quinine
Keep reading about Digoxin
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