Drug & supplement interaction

Syrian Rue + Palonosetron

Palonosetron brand name: Aloxi.

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

Syrian Rue has a moderate interaction with Palonosetron. Theoretically, Syrian rue might increase the risk of serotonergic adverse effects, including serotonin syndrome, when taken with serotonergic drugs.

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

Syrian Rue and Palonosetron

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

Moderate

SEROTONERGIC DRUGS

Why this applies to Palonosetron

Palonosetron falls under SEROTONERGIC DRUGS — the group Syrian Rue interacts with.

Theoretically, Syrian rue might increase the risk of serotonergic adverse effects, including serotonin syndrome, when taken with serotonergic drugs.
Syrian rue contains harmaline and harmine, which have demonstrated strong, reversible inhibition of monoamine oxidase (MAO) A and weak inhibition of MAO B in animal and in vitro research. This may increase the risk for adverse effects with serotonergic drugs.
Severity Moderate Likelihood Possible Evidence D

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 thinking behind pairing these two. Syrian Rue contains harmala alkaloids that block an enzyme called MAO, which normally helps clear serotonin from your system. Palonosetron (Aloxi) works on serotonin too, but in a different way, by blocking certain serotonin receptors to calm nausea after chemo or surgery. The worry is that stacking serotonin-active substances could theoretically nudge you toward serotonin syndrome, which can show up as agitation, a racing heart, sweating, shivering, or muscle twitching.

I want to keep this in perspective. This concern comes only from lab and animal research, not real patient cases, so it's mostly theoretical. Still, since Syrian Rue is risky on its own and Palonosetron is given around chemo or surgery, please loop in your oncology team or pharmacist before mixing them.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Kawanishi, K., Hashimoto, Y., Fujiwara, M., Kataoka, Y., and Ueki, S. Pharmacological characteristics of abnormal behavior induced by harmine with special reference to tremor in mice. J Pharmacobiodyn 1981;4(7):520-527. PubMed
  2. Herraiz, T., Gonzalez, D., Ancin-Azpilicueta, C., Aran, V. J., and Guillen, H. beta-Carboline alkaloids in Peganum harmala and inhibition of human monoamine oxidase (MAO). Food Chem Toxicol 2010;48(3):839-845. PubMed
  3. Fuller, R. W., Wong, C. J., and Hemrick-Luecke, S. K. MD 240928 and harmaline: opposite selectivity in antagonism of the inactivation of types A and B monoamine oxidase by pargyline in mice. Life Sci 1986;38(5):409-412. PubMed
  4. Abdel-Fattah, A. F., Matsumoto, K., Murakami, Y., Adel-Khalek, Gammaz H., Mohamed, M. F., and Watanabe, H. Central serotonin level-dependent changes in body temperature following administration of tryptophan to pargyline- and harmaline-pretreated rats. Ge PubMed
  5. Bergstrom, M., Westerberg, G., and Langstrom, B. 11C-harmine as a tracer for monoamine oxidase A (MAO-A): in vitro and in vivo studies. Nucl Med Biol 1997;24(4):287-293. PubMed
  6. Gerardy, J. Effect of moclobemide on rat brain monoamine oxidase A and B: comparison with harmaline and clorgyline. Prog Neuropsychopharmacol Biol Psychiatry 1994;18(4):793-802.
  7. Sacher, J., Houle, S., Parkes, J., Rusjan, P., Sagrati, S., Wilson, A. A., and Meyer, J. H. Monoamine oxidase A inhibitor occupancy during treatment of major depressive episodes with moclobemide or St. John's wort: an [11C]-harmine PET study. J Psychiatry

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

Syrian Rue Also Interacts With Other Medications

Syrian Rue has 1,121 moderate known drug interactions in our database — the Palonosetron one above is one of them. If you take anything else, check it against the full list below.

Moderate 1,121 No known interaction 1,709 (incl. Palonosetron)
Taking anything else?

Check Another of Your Medications Against Syrian Rue

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

Everything else you take

See Every Supplement That Interacts With Palonosetron

This page covers Syrian Rue only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Palonosetron page lists 21 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Lithium (major), 5-htp (moderate), Acetyl-l-carnitine (moderate), Ayahuasca (moderate) and Black Cohosh (moderate).

By severity: 1 major · 18 moderate · 2 minor.

From our pharmacist’s overview on the Palonosetron page

“Palonosetron (Aloxi) prevents nausea and vomiting from chemotherapy, and it works through the serotonin system, which is exactly where every supplement on this list pushes. All 21 entries raise the same concern, adding to serotonin activity and increasing the chance of serotonin syndrome, a reaction that can bring agitation, rapid hear…”

Reviewed by 2 · Jul 18, 2026

Open the Palonosetron interaction page

How much people look this up

Where Syrian Rue and Palonosetron 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 Syrian Rue
Steady interest

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

29 days ago today
Medication Palonosetron
Top half

#1,130 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 Syrian Rue

What is Syrian Rue?

  • Traditional remedy for digestive complaints
  • Used as a sedative or for mood
  • Antimicrobial and antiparasitic folk use
  • Used as a dye and incense
  • Recreational psychoactive use

Syrian Rue (Peganum harmala) is a traditional plant whose seeds contain potent compounds called harmala alkaloids, including MAO-inhibiting harmine and harmaline. There is little reliable human evidence that it safely treats any condition, and it carries real risks of toxicity, so it is not recommended for self-treatment. Talk to a pharmacist or doctor before considering it.

Read the full Syrian Rue monograph & all interactions
Medication

About Palonosetron Injection

What Is Palonosetron Injection Used For?

Brand name: Aloxi

Palonosetron hydrochloride injection is used in adults to prevent nausea and vomiting caused by moderately or highly emetogenic (nausea-causing) cancer chemotherapy — including both the immediate reaction and the delayed reaction that can happen days later. It is also approved in adults to prevent postoperative nausea and vomiting (PONV) for up to 24 hours after surgery, given right before anesthesia is started.

In children aged 1 month to less than 17 years, it is used to prevent acute (immediate) nausea and vomiting from emetogenic cancer chemotherapy, including highly emetogenic regimens. Posfrea is the brand name under which this intravenous injection is available.

See full Palonosetron Injection drug information
Keep checking

Other Drugs & Syrian Rue

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

0Major
1,121Moderate
0Minor
1,708No known interaction
1,121 Moderate 1,708 No interaction
Moderate

1,121 interactions

Showing 60 of 1,121 moderate interactions — see all 1,121 on the Syrian Rue page.

No interaction 1,708 drugs checked — show the list

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

Showing the 60 most looked-up of 1,708 medications checked with no known interaction — see the full Syrian Rue list.

See the full Syrian Rue interactions page
See every supplement checked against Palonosetron, 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
Syrian Rue monograph › Uses, safety, and every drug interaction in one place Palonosetron supplement interactions › Every supplement checked against Palonosetron, ranked by severity Palonosetron Injection 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 Syrian Rue and Palonosetron Together: Common Questions

Can you take Syrian Rue with Palonosetron?
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 Syrian Rue and Palonosetron 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 Palonosetron and Syrian Rue?

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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.