Drug & supplement interaction

Grapefruit + Arsenic Trioxide (prescription drug)

Arsenic Trioxide (prescription drug) brand name: Trisenox.

Major Interaction
Medically reviewed by · Updated October 2026
The bottom line Major

Grapefruit has a major interaction with Arsenic Trioxide (prescription drug). Grapefruit or grapefruit juice, especially if consumed in large amounts, can cause additive QT interval prolongation when taken with QT interval-prolonging drugs, potentially increasing the risk of ventricular arrhythmias.

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

Grapefruit and Arsenic Trioxide (prescription drug)

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

Major

QT INTERVAL-PROLONGING DRUGS

Why this applies to Arsenic Trioxide (prescription drug)

Arsenic Trioxide (prescription drug) falls under QT INTERVAL-PROLONGING DRUGS — the group Grapefruit interacts with.

Grapefruit or grapefruit juice, especially if consumed in large amounts, can cause additive QT interval prolongation when taken with QT interval-prolonging drugs, potentially increasing the risk of ventricular arrhythmias.
Clinical research in healthy volunteers shows that drinking 6 liters of grapefruit juice over 6 hours prolonged the QTc by a peak amount of 14 milliseconds (ms). This prolongation was similar to the QT prolongation caused by the drug moxifloxacin. In individuals with long QT syndrome, a smaller dose of grapefruit juice, 1.5 liters, resulted in a greater peak QTc prolongation of about 30 ms. The effect of smaller quantities of grapefruit juice on the QT interval is unclear.
Severity Major Likelihood Probable Evidence B

Interaction 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..

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

Here's something worth knowing about Trisenox (arsenic trioxide). This medicine is already known to stretch out the heart's electrical reset time, what we call the QT interval. Grapefruit can do the same thing on its own, so the worry is that the two effects stack on top of each other. A longer QT can occasionally trigger a dangerous heart rhythm, with symptoms like a racing or fluttering heartbeat, dizziness, or fainting.

In studies it took fairly large amounts of grapefruit juice to noticeably move the QT, so a bite of fruit now and then is far less concerning than drinking a lot regularly. Since arsenic trioxide is a serious cancer treatment with this risk built in, I'd play it safe and run your grapefruit habit by your oncology team or pharmacist before continuing it.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Chorin E, Hochstadt A, Granot Y, et al. Grapefruit juice prolongs the QT interval of healthy volunteers and patients with long QT syndrome. Heart Rhythm. 2019. pii: S1547-5271(19)30368-6. PubMed

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

Grapefruit Also Interacts With Other Medications

Grapefruit has 777 major, 151 moderate, 62 minor known drug interactions in our database — the Arsenic Trioxide (prescription drug) one above is one of them. If you take anything else, check it against the full list below.

Major 777 Moderate 151 Minor 62 No known interaction 1,840 (incl. Arsenic Trioxide (prescription drug))
Taking anything else?

Check Another of Your Medications Against Grapefruit

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

From our Q&A

Questions About Grapefruit or Arsenic Trioxide (prescription drug)

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Grapefruit or Arsenic Trioxide (prescription drug), 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 Arsenic Trioxide (prescription drug)

This page covers Grapefruit only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Arsenic Trioxide (prescription drug) page lists 13 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: American Hellebore (major), Arsenic (major), Cesium (major), Ephedra (major) and Sida Cordifolia (major).

By severity: 6 major · 7 moderate.

From our pharmacist’s overview on the Arsenic Trioxide (prescription drug) page

“Every ingredient on this page interacts with arsenic trioxide (Trisenox) in the same way, by stretching the QT interval, the heart's electrical reset time, further than the drug already pushes it. Trisenox treats acute promyelocytic leukemia and prolongs the QT interval in up to 40 percent of patients all by itself, so anything that ad…”

Reviewed by 2 · Jul 18, 2026

Open the Arsenic Trioxide (prescription drug) interaction page

One more smart check

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

We hold 1,144 real supplement products containing Grapefruit, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Grapefruit. Your product may carry other ingredients that interact with Arsenic Trioxide (prescription drug) too, on top of Grapefruit — 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 Grapefruit and Arsenic Trioxide (prescription drug) 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 Grapefruit
Top 10%

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

29 days ago today
Medication Arsenic Trioxide (prescription drug)
Top half

#1,007 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 Grapefruit

What is Grapefruit?

Grapefruit
  • Source of vitamin C
  • Digestive complaints
  • Antimicrobial (seed extract)
  • Weight management
  • Skin and cosmetic uses

Grapefruit is a nutritious citrus fruit rich in vitamin C and other nutrients, and it is generally safe to eat. However, grapefruit is famous for serious interactions with many prescription medicines, so anyone taking medication should check with a pharmacist or doctor before consuming it regularly.

Read the full Grapefruit monograph & all interactions
Medication

About Arsenic Trioxide Injection

What Is Arsenic Trioxide Injection Used For?

Brand name: Trisenox

Arsenic Trioxide Injection treats acute promyelocytic leukemia (APL), a type of blood cancer. It is only used when the leukemia has a specific genetic marker: the t(15;17) translocation or PML/RAR-alpha gene expression.

It is used in two settings. For adults with newly diagnosed low-risk APL, it is given together with tretinoin. For APL that has relapsed or did not respond to retinoid and anthracycline chemotherapy, it is used to bring on remission and then to consolidate (lock in) that remission.

See full Arsenic Trioxide Injection drug information
Keep checking

Other Drugs & Grapefruit

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

777Major
151Moderate
62Minor
1,839No known interaction
777 Major 151 Moderate 62 Minor 1,839 No interaction
Major

777 interactions

Showing 60 of 777 major interactions — see all 777 on the Grapefruit page.

Moderate

151 interactions

Showing 60 of 151 moderate interactions — see all 151 on the Grapefruit page.

Minor

62 interactions

Showing 60 of 62 minor interactions — see all 62 on the Grapefruit page.

No interaction 1,839 drugs checked — show the list

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

Showing the 60 most looked-up of 1,839 medications checked with no known interaction — see the full Grapefruit list.

See the full Grapefruit interactions page
See every supplement checked against Arsenic Trioxide (prescription drug), 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
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Pharmacist Counseling Corner

Taking Grapefruit and Arsenic Trioxide (prescription drug) Together: Common Questions

Can you take Grapefruit with Arsenic Trioxide (prescription drug)?
This is rated a major interaction, so the combination is best avoided unless your doctor or pharmacist has specifically told you otherwise. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Grapefruit and Arsenic Trioxide (prescription drug) interaction?
We rate it Major. This is a clinically significant combination that is generally best avoided, or used only under the direct supervision of your physician or pharmacist.

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

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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.