Drug & supplement interaction

Jequirity + Fostamatinib

Fostamatinib brand name: Tavalisse.

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

Jequirity has a minor interaction with Fostamatinib. In vitro research shows that jequirity extract inhibits CYP3A4 enzymes.

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

Jequirity and Fostamatinib

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

Minor

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

Why this applies to Fostamatinib

Fostamatinib falls under CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES — the group Jequirity interacts with.

In vitro research shows that jequirity extract inhibits CYP3A4 enzymes. Theoretically, taking jequirity may inhibit the metabolism of CYP3A4 substrates.
Severity Minor Likelihood Unlikely Evidence D

Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans..

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

Here's the quick version: your body uses an enzyme called CYP3A4 to help break down the active form of fostamatinib (Tavalisse). Lab studies suggest jequirity can slow that enzyme down. In theory, if the enzyme works slower, more of the drug could linger in your system, which might mean stronger effects and a higher chance of side effects like diarrhea, high blood pressure, nausea, or liver enzyme changes.

That said, I want to be straight with you: this is only test-tube data, rated as minor and unlikely, so it's far from proven in real people. The bigger issue is that jequirity seeds contain abrin, a severe poison, and simply should not be taken. Please don't use it, and check with your doctor or pharmacist about anything you add alongside fostamatinib.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Ai C, Miao X, Wang L, He J. Discovery and Activity Evaluation of the Inhibitory Effect of Four Kinds Traditional Chinese Medicine Extracts on the CYP3A4 Enzyme. Comb Chem High Throughput Screen 2022.

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

Jequirity Also Interacts With Other Medications

Jequirity has 208 moderate, 602 minor known drug interactions in our database — the Fostamatinib one above is one of them. If you take anything else, check it against the full list below.

Moderate 208 Minor 602 No known interaction 2,020 (incl. Fostamatinib)
Taking anything else?

Check Another of Your Medications Against Jequirity

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

Everything else you take

See Every Supplement That Interacts With Fostamatinib

This page covers Jequirity only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Fostamatinib page lists 209 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Beer (major), Grapefruit (major), Siberian Cocklebur (major) and St. John's Wort (major).

By severity: 6 major · 167 moderate · 36 minor.

From our pharmacist’s overview on the Fostamatinib page

“I would treat the supplement list for fostamatinib (Tavalisse), a medicine that raises platelet counts in chronic immune thrombocytopenia, with real care. Most of what shows up here involves CYP3A4, the liver enzyme that clears fostamatinib, so grapefruit can drive its blood level up while St.”

Reviewed by 2 · Jul 18, 2026

Open the Fostamatinib interaction page

How much people look this up

Where Jequirity and Fostamatinib 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 Jequirity
Top half

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

29 days ago today
Medication Fostamatinib
Top 25%

#468 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 Jequirity

What is Jequirity?

Jequirity
  • Asthma and cough
  • Fever
  • Sore throat and bronchitis
  • Liver complaints (hepatitis)
  • Constipation
  • Traditional infectious-disease remedies

Jequirity (Abrus precatorius) is a tropical plant whose bright red, black-tipped seeds contain abrin, one of the most toxic plant proteins known. Despite a long history in traditional medicine, the seeds are dangerously poisonous and there is no reliable evidence that it is safe or effective. It should not be used as a supplement or medicine.

Read the full Jequirity monograph & all interactions
Medication

About Fostamatinib

What Is Fostamatinib Used For?

Brand name: Tavalisse

Tavalisse (fostamatinib) is used to treat thrombocytopenia — dangerously low platelet counts — in adults with chronic immune thrombocytopenia (ITP). It is specifically for people whose platelet counts have not improved enough with at least one earlier ITP treatment.

The goal is to raise platelet counts high enough to reduce the risk of serious bleeding. If platelet counts do not respond sufficiently after 12 weeks, the medication is typically stopped.

See full Fostamatinib drug information
Keep checking

Other Drugs & Jequirity

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

0Major
208Moderate
602Minor
2,019No known interaction
208 Moderate 602 Minor 2,019 No interaction
Moderate

208 interactions

Showing 60 of 208 moderate interactions — see all 208 on the Jequirity page.

Minor

602 interactions

Showing 60 of 602 minor interactions — see all 602 on the Jequirity page.

No interaction 2,019 drugs checked — show the list

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

Showing the 60 most looked-up of 2,019 medications checked with no known interaction — see the full Jequirity list.

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

Can you take Jequirity with Fostamatinib?
There is only a minor interaction, which is usually not serious. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Jequirity and Fostamatinib interaction?
We rate it Minor. This interaction is generally not clinically significant, but it remains worth noting and discussing with your pharmacist.

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

Still Have a Question About Fostamatinib and Jequirity?

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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.