Drug & supplement interaction

Sweet Orange + Quinidine

Quinidine brand names: Quinaglute Duratabs, Quinaglute, Duraquin, Cardioquin, Cin-Quin, and others.

Moderate Interaction
Medically reviewed by · Updated September 2026
The bottom line Moderate

Sweet Orange has a moderate interaction with Quinidine. Sweet orange juice seems to modulate P-glycoprotein (P-gp), which might affect the blood levels of P-gp substrates.

Read the full interaction report
SeverityModerate
LikelihoodPossible
EvidenceB
What do Severity, Likelihood & Evidence mean?
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Interaction report

Sweet Orange and Quinidine

Here is the interaction we found between these two, with the evidence behind it.

Moderate

P-GLYCOPROTEIN SUBSTRATES

Why this applies to Quinidine

Quinidine falls under P-GLYCOPROTEIN SUBSTRATES — the group Sweet Orange interacts with.

Sweet orange juice seems to modulate P-glycoprotein (P-gp), which might affect the blood levels of P-gp substrates.
Animal and in vitro research suggest that orange juice extract inhibits drug efflux by P-gp, increasing absorption and levels of P-gp substrates. In contrast, pharmacokinetic research in humans shows that drinking large amounts of sweet orange juice decreases absorption and levels of the P-gp substrate celiprolol. This suggests that orange juice actually induces drug efflux by P-gp or affects drug levels by another mechanism such as inhibiting the gut drug transporter called organic anion transporting polypeptide (OATP). Until more is known, sweet orange juice should be used cautiously in people taking P-gp substrates.
Severity Moderate Likelihood Possible Evidence B

Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the situation with quinidine and sweet orange juice. Quinidine relies on a little 'pump' in your gut called P-glycoprotein that helps move drugs in and out of your system. Sweet orange juice seems to nudge this pump, but the research is mixed. In one human study, large amounts of orange juice actually lowered the blood levels of a similar drug, while lab studies showed the opposite. So we honestly can't be sure which way quinidine would go.

Because quinidine is a heart rhythm drug with a narrow safety window, even small shifts matter. Too little may let your irregular heartbeat slip back; too much can cause dizziness, nausea, ringing in the ears, or new rhythm problems. A glass of juice now and then is usually no big deal, but I'd skip large daily amounts and check with your pharmacist or doctor first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Bailey DG, Dresser GK, Munoz C, et al. Reduction of fexofenadine bioavailability by fruit juices. Clin Pharmacol Ther 2001;69:P21.
  2. Lilja JJ, Juntti-Patinen L, Neuvonen PJ. Orange juice substantially reduces the bioavailability of the beta-adrenergic-blocking agent celiprolol. Clin Pharmacol Ther 2004;75:184-90.
  3. Tian R, Koyabu N, Takanaga H, et al. Effects of grapefruit juice and orange juice on the intestinal efflux of P-glycoprotein substrates. Pharm Res 2002;19:802-9. PubMed
  4. Takanaga H, Ohnishi A, Yamada S, et al. Polymethoxylated flavones in orange juice are inhibitors of P-glycoprotein but not cytochrome P450 3A4. J Pharmacol Exp Ther 2000;293:230-6. DOI

What These Ratings Mean

Every interaction above is graded three ways — here’s the key to each label.

Severity how clinically significant the interaction is
Major

Clinically significant. Avoid the combination, or use only under close professional supervision.

Moderate

Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.

Minor

Generally not serious. Be aware of it and mention it to your pharmacist.

Likelihood how strong the evidence is that the interaction actually happens in people
  • LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
  • ProbableInteraction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
  • PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.
  • UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Evidence the quality of the studies behind the rating (graded A–D)
  • AHigh-quality meta-analysis (quantitative systematic review).
  • BCase-control study.
  • CConsensus.
  • DAnecdotal evidence.

These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.

Keep it in perspective

Sweet Orange Also Interacts With Other Medications

Sweet Orange has 48 major, 197 moderate known drug interactions in our database — the Quinidine one above is one of them. If you take anything else, check it against the full list below.

Major 48 Moderate 197 No known interaction 2,585 (incl. Quinidine)
Taking anything else?

Check Another of Your Medications Against Sweet Orange

Covers the 2,830 medications we’ve checked against Sweet Orange. Pick one to open its full report.

From our Q&A

Questions About Sweet Orange or Quinidine

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Sweet Orange or Quinidine, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Quinidine

This page covers Sweet Orange only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Quinidine page lists 207 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), American Hellebore (major), Arsenic (major), Beer (major) and Cesium (major).

By severity: 15 major · 157 moderate · 35 minor.

From our pharmacist’s overview on the Quinidine page

“Grapefruit belongs nowhere near quinidine. The juice blocks the main enzyme that clears this heart rhythm medicine, so quinidine levels can climb into dangerous territory, and it leads a list of 207 supplement and herbal ingredients I would treat with real seriousness, 15 of them rated major.”

Reviewed by 2 · Jul 18, 2026

Open the Quinidine interaction page

One more smart check

Taking Sweet Orange as Part of a Dietary Supplement Product? Check It for Interactions

We hold 678 real supplement products containing Sweet Orange, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Sweet Orange. Your product may carry other ingredients that interact with Quinidine too, on top of Sweet Orange — and those would not show on this page. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Sweet Orange and Quinidine Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement Sweet Orange
Top 25%

#266 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Quinidine
Top 25%

#356 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Supplement

About Sweet Orange

What is Sweet Orange?

Sweet Orange
  • Vitamin C source
  • Digestive upset
  • Stress and relaxation (aromatherapy)
  • Cold and respiratory support
  • Antioxidant support

Sweet orange is a common citrus fruit that is a good source of vitamin C, fiber, and antioxidants, and is enjoyed as a food worldwide. Its peel and essential oil are used in aromatherapy and traditional remedies, but strong scientific proof for most medicinal claims is limited. The fruit and juice are safe for most people as food, while concentrated oils and extracts deserve more caution.

Read the full Sweet Orange monograph & all interactions
Medication

About Quinidine

What Is Quinidine Used For?

Brand names: Quinaglute Duratabs, Quinaglute, Duraquin, Cardioquin, Cin-Quin, Quinora, Lin-Qin, Quinova, Quinidex Extentabs

Quinidine is used to help restore a normal heart rhythm in people with atrial fibrillation or atrial flutter (irregular, rapid heart rhythms originating in the upper chambers). It is also used on an ongoing basis to reduce how often those episodes come back, in patients whose episodes are frequent and poorly tolerated — but only after other options have been tried first.

Quinidine sulfate oral tablets and quinidine gluconate extended-release oral tablets are both approved for these heart-rhythm uses. Quinidine sulfate tablets are additionally used as part of an approved treatment regimen for life-threatening Plasmodium falciparum malaria, in combination with quinidine gluconate injection (the central component of that regimen). Both formulations may also be used to suppress recurrent, documented life-threatening ventricular arrhythmias (dangerous rapid rhythms in the lower chambers of the heart), such as sustained ventricular tachycardia.

See full Quinidine drug information
Keep checking

Other Drugs & Sweet Orange

Browse every other medication we’ve checked against Sweet Orange — both the ones with a known interaction and the ones without. Select any drug for the full detail.

48Major
197Moderate
0Minor
2,584No known interaction
48 Major 197 Moderate 2,584 No interaction
Major

48 interactions

Moderate

197 interactions

Showing 60 of 197 moderate interactions — see all 197 on the Sweet Orange page.

No interaction 2,584 drugs checked — show the list

We also checked Sweet Orange against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,584 medications checked with no known interaction — see the full Sweet Orange list.

See the full Sweet Orange interactions page
See every supplement checked against Quinidine, ranked by severity
Sources

Sources & How We Checked

Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

Keep exploring
Sweet Orange monograph › Uses, safety, and every drug interaction in one place Quinidine supplement interactions › Every supplement checked against Quinidine, ranked by severity Quinidine drug information › The full plain-English guide to this medication Supplement interaction checker › Check any supplement or product against your medications Browse medications A–Z › Every drug we've checked against herbs & supplements Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking Sweet Orange and Quinidine Together: Common Questions

Can you take Sweet Orange with Quinidine?
There is a moderate interaction, so it may be acceptable with monitoring or timing changes — but check with your pharmacist first. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Sweet Orange and Quinidine interaction?
We rate it Moderate. This combination may require monitoring, a dose adjustment, or separating the times you take each one. Consult your pharmacist before using them together.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Still Have a Question About Quinidine and Sweet Orange?

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This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.