Drug & supplement interaction

Fucus Vesiculosus + Selexipag

Selexipag brand name: Uptravi.

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

Selexipag falls into 2 drug categories that Fucus Vesiculosus can interact with; the most serious is rated minor. Theoretically, taking Fucus vesiculosus with antiplatelet or anticoagulant drugs might increase the risk of bruising and bleeding.

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

Fucus Vesiculosus and Selexipag

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. Selexipag 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

ANTICOAGULANT/ANTIPLATELET DRUGS

1 of 2

Why this applies to Selexipag

Selexipag falls under ANTICOAGULANT/ANTIPLATELET DRUGS — the group Fucus Vesiculosus interacts with.

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 thing to know about this pairing: the concern on file is really about bruising and bleeding, because one compound in bladderwrack, called fucoidan, slows blood clotting in the test tube. Selexipag (Uptravi) isn't a blood thinner itself, but it does relax blood vessels in the lungs and can come with side effects like flushing, headache, and a bit more bleeding risk in some folks.

The good news is the evidence here is weak. This effect mostly shows up in lab studies, and when fucoidan is swallowed it barely gets absorbed, so real-world clotting changes seem unlikely. Still, since both could nudge bleeding in the same direction, it's worth a quick chat with your pharmacist or doctor before adding bladderwrack, especially given its unpredictable iodine load.

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
Minor

CYTOCHROME P450 2C8 (CYP2C8) SUBSTRATES

2 of 2

Selexipag also falls under CYTOCHROME P450 2C8 (CYP2C8) SUBSTRATES.

Theoretically, concomitant use of Fucus vesiculosus with CYP2C8 substrates might increase the risk for adverse effects.
In vitro research shows that fucoidan, a constituent of Fucus vesiculosus, inhibits CYP2C8. 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

Here's the gist for Uptravi (selexipag). Your body clears it using an enzyme called CYP2C8. Lab studies suggest that fucoidan, one of the compounds in bladderwrack, may slow that enzyme down a bit. If that slowing happened in real life, selexipag could build up slightly, which might nudge up its usual side effects like headache, flushing, jaw pain, nausea, diarrhea, or muscle aches.

The honest part: this is purely a test-tube finding, not something seen in actual patients, and it's rated minor. So I wouldn't lose sleep over it. Still, because bladderwrack's iodine can also mess with your thyroid, it's worth a quick chat with your pharmacist or doctor before adding it.

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.

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 Selexipag 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. Selexipag)
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 Selexipag

This page covers Fucus Vesiculosus only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Selexipag page lists 291 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), American Hellebore (major), American Mistletoe (major), Danshen (major) and Piracetam (major).

By severity: 6 major · 258 moderate · 27 minor.

From our pharmacist’s overview on the Selexipag page

“People take selexipag (Uptravi) for pulmonary arterial hypertension, dangerously high pressure in the arteries of the lungs, and that diagnosis raises the stakes on this list of 291 interacting supplements. I would treat it with real vigilance.”

Reviewed by 2 · Jul 18, 2026

Open the Selexipag interaction page

How much people look this up

Where Fucus Vesiculosus and Selexipag 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
Steady interest

#1,091 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Selexipag
Top 25%

#353 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 Selexipag

What Is Selexipag Used For?

Brand name: Uptravi

Selexipag tablets are used to treat pulmonary arterial hypertension (PAH, WHO Group I) — a type of high blood pressure in the arteries of the lungs. The goal is to slow the disease from getting worse and to reduce the chances of being hospitalized because of PAH.

Uptravi (selexipag) tablets are approved for both adults and children aged 2 years and older. Uptravi for injection (intravenous) is also available for adult patients who are already on Uptravi tablets but temporarily cannot take medicine by mouth.

See full Selexipag 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 Selexipag, 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 Selexipag supplement interactions › Every supplement checked against Selexipag, ranked by severity Selexipag 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 Selexipag Together: Common Questions

Can you take Fucus Vesiculosus with Selexipag?
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 Selexipag?
Selexipag 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 Selexipag 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.