Drug & supplement interaction

Fucus Vesiculosus + Tivozanib Hydrochloride

Tivozanib Hydrochloride brand name: Fotivda.

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

Tivozanib Hydrochloride falls into 2 drug categories that Fucus Vesiculosus can interact with; the most serious is rated minor. Theoretically, concomitant use of Fucus vesiculosus with CYP3A4 substrates might increase the risk for adverse effects.

Read the full interaction report
SeverityMinor
LikelihoodPossible
Interactions2
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Fucus Vesiculosus and Tivozanib Hydrochloride

These two interact in 2 distinct ways. Each one is explained separately below.

Why Are There 2 Interactions?

Fucus Vesiculosus interacts with whole categories of medication. Tivozanib Hydrochloride falls into 2 of those categories, so it can interact with Fucus Vesiculosus in 2 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Minor).

Minor

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

1 of 2

Why this applies to Tivozanib Hydrochloride

Tivozanib Hydrochloride falls under CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES — the group Fucus Vesiculosus interacts with.

Theoretically, concomitant use of Fucus vesiculosus with CYP3A4 substrates might increase the risk for adverse effects.
In vitro research shows that fucoidan, a constituent of Fucus vesiculosus, inhibits CYP3A4. This interaction has not been reported in humans.
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

Your body clears tivozanib (Fotivda) mainly through a liver enzyme called CYP3A4. In test-tube studies, a compound in bladderwrack called fucoidan appears to slow that enzyme down. If that were to happen in real life, tivozanib could build up a little more than expected, which might mean stronger side effects like high blood pressure, fatigue, diarrhea, mouth sores, or hand-foot skin reactions.

Here's the reassuring part: this is only a theoretical concern based on lab work, and it has never actually been reported in people. The bigger reason to be cautious is bladderwrack's heavy, unpredictable iodine load, which can upset your thyroid. Since you're being treated for kidney cancer, please run any seaweed supplement past your oncologist or pharmacist first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Mathew L, Burney M, Gaikwad A, et al. Preclinical evaluation of safety of fucoidan extracts from Undaria pinnatifida and Fucus vesiculosus for use in cancer treatment. Integr Cancer Ther 2017;16(4):572-84.
Minor

ANTICOAGULANT/ANTIPLATELET DRUGS

2 of 2

Tivozanib Hydrochloride also falls under ANTICOAGULANT/ANTIPLATELET DRUGS.

Theoretically, taking Fucus vesiculosus with antiplatelet or anticoagulant drugs might increase the risk of bruising and bleeding.
In vitro evidence suggests that a constituent of Fucus vesiculosus, known as fucoidan, has anticoagulant effects. However, in clinical research, fucoidan does not seem to have significant anticoagulant activity when taken orally, possibly due to poor absorption.
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 gist for Fotivda (tivozanib). One of the natural sugars in bladderwrack, called fucoidan, can thin the blood a little in lab dishes. The thought is that pairing it with a medicine that affects bleeding could add up to more bruising or bleeding. Tivozanib isn't a classic blood thinner, but it's a kinase inhibitor that can already raise blood pressure and carries its own bleeding risk, so this is worth keeping on your radar.

The good news: when people actually swallow fucoidan, the body barely absorbs it, so it doesn't seem to thin blood much in real life. This is a theoretical, low-likelihood concern. Still, since you're on cancer therapy, run any bladderwrack or seaweed supplement past your oncology team or pharmacist first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Durig J, Bruhn T, Zurborn KH, et al. Anticoagulant fucoidan fractions from Fucus vesiculosus induce platelet activation in vitro. Thromb Res 1997;85:479-91. PubMed
  2. Cumashi, A., Ushakova, N. A., Preobrazhenskaya, M. E., D'Incecco, A., Piccoli, A., Totani, L., Tinari, N., Morozevich, G. E., Berman, A. E., Bilan, M. I., Usov, A. I., Ustyuzhanina, N. E., Grachev, A. A., Sanderson, C. J., Kelly, M., Rabinovich, G. A., I
  3. Irhimeh, M. R., Fitton, J. H., and Lowenthal, R. M. Pilot clinical study to evaluate the anticoagulant activity of fucoidan. Blood Coagul.Fibrinolysis 2009;20(7):607-610. PubMed
  4. Church FC, Meade JB, Treanor RE, and et al. Antithrombin activity of fucoidan. The interaction of fucoidan with heparin cofactor II, antithrombin III, and thrombin. J Biol Chem 2-25-1989;264(6):3618-3623. 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

Fucus Vesiculosus Also Interacts With Other Medications

Fucus Vesiculosus has 23 moderate, 867 minor known drug interactions in our database — the Tivozanib Hydrochloride one above is among them. If you take anything else, check it against the full list below.

Moderate 23 Minor 867 No known interaction 1,940 (incl. Tivozanib Hydrochloride)
Taking anything else?

Check Another of Your Medications Against Fucus Vesiculosus

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

Everything else you take

See Every Supplement That Interacts With Tivozanib Hydrochloride

This page covers Fucus Vesiculosus only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Tivozanib Hydrochloride page lists 288 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Asarabacca (major), Danshen (major), Grapefruit (major) and Piracetam (major).

By severity: 7 major · 239 moderate · 42 minor.

From our pharmacist’s overview on the Tivozanib Hydrochloride page

“Tivozanib (Fotivda), an oral targeted therapy for advanced kidney cancer, has a supplement list that calls for genuine vigilance. Seven of the 288 ingredients on file are rated major, and those seven deserve your attention first.”

Reviewed by 2 · Jul 18, 2026

Open the Tivozanib Hydrochloride interaction page

How much people look this up

Where Fucus Vesiculosus and Tivozanib Hydrochloride 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 Fucus Vesiculosus
Top half

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

29 days ago today
Medication Tivozanib Hydrochloride
Top 25%

#689 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 Fucus Vesiculosus

What is Fucus Vesiculosus?

Fucus Vesiculosus
  • Thyroid support
  • Iodine source
  • Weight management
  • Joint and skin care (topical)
  • Constipation and digestive support

Fucus vesiculosus (bladderwrack) is a brown seaweed rich in iodine that has been used traditionally for thyroid concerns, weight, and skin. There is little solid human evidence to support most of these uses, and its high and variable iodine content can actually harm the thyroid. Talk to a pharmacist or doctor before using it, especially if you have a thyroid condition.

Read the full Fucus Vesiculosus monograph & all interactions
Medication

About Tivozanib

What Is Tivozanib Used For?

Brand name: Fotivda

Fotivda (tivozanib) is used to treat adults with advanced renal cell carcinoma (a type of kidney cancer) that is relapsed or refractory — meaning it has come back or stopped responding to treatment — after two or more prior systemic (whole-body) cancer therapies.

See full Tivozanib drug information
Keep checking

Other Drugs & Fucus Vesiculosus

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

0Major
23Moderate
867Minor
1,939No known interaction
23 Moderate 867 Minor 1,939 No interaction
Moderate

23 interactions

Minor

867 interactions

Showing 60 of 867 minor interactions — see all 867 on the Fucus Vesiculosus page.

No interaction 1,939 drugs checked — show the list

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

Showing the 60 most looked-up of 1,939 medications checked with no known interaction — see the full Fucus Vesiculosus list.

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

Can you take Fucus Vesiculosus with Tivozanib Hydrochloride?
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.
Why are there 2 interactions listed for Fucus Vesiculosus and Tivozanib Hydrochloride?
Tivozanib Hydrochloride belongs to more than one drug category, and Fucus Vesiculosus interacts with each of those categories a little differently. We list every one so nothing is missed — your overall risk is driven by the most serious of them.
How serious is the Fucus Vesiculosus and Tivozanib Hydrochloride 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

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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.