Drug & supplement interaction

Fever Bark + Ibrutinib

Ibrutinib brand name: Imbruvica.

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

Fever Bark has a minor interaction with Ibrutinib. Theoretically, combining fever bark with antiplatelet or anticoagulant drugs might have additive effects; however, this has not been reported in clinical research.

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

Fever Bark and Ibrutinib

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

Minor

ANTICOAGULANT/ANTIPLATELET DRUGS

Why this applies to Ibrutinib

Ibrutinib falls under ANTICOAGULANT/ANTIPLATELET DRUGS — the group Fever Bark interacts with.

Theoretically, combining fever bark with antiplatelet or anticoagulant drugs might have additive effects; however, this has not been reported in clinical research.
Research in healthy adults shows that taking yohimbine, a constituent of fever bark, in doses of 8 mg or more, seems to inhibit platelet aggregation in vitro by binding to the alpha-2 adrenoceptor. The effects of fever bark itself are unclear.
Severity Minor 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 gist if you're taking Imbruvica (ibrutinib) and thinking about fever bark. Ibrutinib on its own can make you bleed and bruise more easily, since it affects how your platelets stick together. Fever bark contains a compound called yohimbine that, in lab studies, seemed to make platelets a little less sticky too. So in theory, stacking the two could add up and nudge your bleeding risk higher.

I want to be honest about how soft this is, though. This concern comes only from test-tube research, not from real people, and the effect of fever bark itself is unclear. Still, I'd lean cautious. Please loop in your oncology team or pharmacist before adding fever bark, and watch for unusual bruising, nosebleeds, or bleeding gums.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Mustonen, P., Savola, J., and Lassila, R. Atipamezole, an imidazoline-type alpha(2)-adrenoceptor inhibitor, binds to human platelets and inhibits their adrenaline-induced aggregation more effectively than yohimbine. Thromb.Res 8-1-2000;99(3):231-237.
  2. Berlin, I., Crespo-Laumonnier, B., Cournot, A., Landault, C., Aubin, F., Legrand, J. C., and Puech, A. J. The alpha 2-adrenergic receptor antagonist yohimbine inhibits epinephrine-induced platelet aggregation in healthy subjects. Clin Pharmacol.Ther. 199
  3. Braddock, L., Cowen, P. J., Elliott, J. M., Fraser, S., and Stump, K. Binding of yohimbine and imipramine to platelets in depressive illness. Psychol.Med 1986;16(4):765-773. PubMed
  4. Boon, N. A., Elliott, J. M., Grahame-Smith, D. G., John-Green, T., and Stump, K. A comparison of alpha 2-adrenoreceptor binding characteristics of intact human platelets identified by [3H]-yohimbine and [3H]- dihydroergocryptine. J Auton.Pharmacol 1983;3

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

Fever Bark Also Interacts With Other Medications

Fever Bark has 40 major, 674 moderate, 86 minor known drug interactions in our database — the Ibrutinib one above is one of them. If you take anything else, check it against the full list below.

Major 40 Moderate 674 Minor 86 No known interaction 2,030 (incl. Ibrutinib)
Taking anything else?

Check Another of Your Medications Against Fever Bark

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

Everything else you take

See Every Supplement That Interacts With Ibrutinib

This page covers Fever Bark only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Ibrutinib page lists 282 supplements it has a documented interaction with, worst first, each one explained.

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

By severity: 5 major · 236 moderate · 41 minor.

From our pharmacist’s overview on the Ibrutinib page

“Ibrutinib (Imbruvica) treats blood cancers such as chronic lymphocytic leukemia, and because the drug itself makes bruising and bleeding more likely, adding the wrong supplement here can carry real consequences. Most of the entries below have blood-thinning or antiplatelet activity that stacks on top of that built-in bleeding risk.”

Reviewed by 2 · Jul 18, 2026

Open the Ibrutinib interaction page

How much people look this up

Where Fever Bark and Ibrutinib 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 Fever Bark
Steady interest

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

29 days ago today
Medication Ibrutinib
Top 25%

#575 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 Fever Bark

What is Fever Bark?

Fever Bark
  • Fever
  • Diarrhea
  • Malaria (traditional)
  • Digestive complaints
  • Bitter tonic

Fever bark is the bark of the Australian tree Alstonia constricta, used in traditional medicine for fever, diarrhea, and infections. There is very little reliable human research to support these uses, and the bark contains potent alkaloids that may cause serious side effects. It is best avoided unless used under direct medical supervision.

Read the full Fever Bark monograph & all interactions
Medication

About Ibrutinib

What Is Ibrutinib Used For?

Brand name: Imbruvica

Imbruvica (ibrutinib) is approved for adult patients with chronic lymphocytic leukemia (CLL) / small lymphocytic lymphoma (SLL), including those with a specific genetic change called 17p deletion, and for adult patients with Waldenström's macroglobulinemia (WM), a rare type of blood cancer.

Imbruvica is also approved for chronic graft-versus-host disease (cGVHD) — a complication that can occur after a stem cell transplant — in adults and children aged 1 year and older whose condition did not respond to at least one prior treatment.

See full Ibrutinib drug information
Keep checking

Other Drugs & Fever Bark

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

40Major
674Moderate
86Minor
2,029No known interaction
40 Major 674 Moderate 86 Minor 2,029 No interaction
Major

40 interactions

Moderate

674 interactions

Showing 60 of 674 moderate interactions — see all 674 on the Fever Bark page.

Minor

86 interactions

Showing 60 of 86 minor interactions — see all 86 on the Fever Bark page.

No interaction 2,029 drugs checked — show the list

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

Showing the 60 most looked-up of 2,029 medications checked with no known interaction — see the full Fever Bark list.

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

Can you take Fever Bark with Ibrutinib?
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 Fever Bark and Ibrutinib 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 Ibrutinib and Fever Bark?

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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.