Drug & supplement interaction

Fucus Vesiculosus + Mesalamine

Mesalamine brand names: Pentasa, Asacol, Canasa, Rowasa, Lialda, and others.

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 20, 2026
The bottom line No known interaction

We found no known interaction between Fucus Vesiculosus and Mesalamine in our sources. Absence of a documented interaction is not the same as proven safety, and does not guarantee one does not exist. Do not start, stop, or change a medication or supplement based on this page; confirm with your pharmacist or doctor first. Additionally, although there is no interaction, the label for Mesalamine states a food rule worth keeping to, and the two are separately associated with some of the same side effects, which would make a new symptom harder to attribute to one or the other.

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Interaction report

Fucus Vesiculosus and Mesalamine

We checked these two against our interaction database. Here is what we found.

No Known Interaction Found

We did not find a documented interaction between Mesalamine and Fucus Vesiculosus in our sources. This does not guarantee that the combination is completely free of risk — there is often limited research on supplements and herbal products, especially around drug interactions.

If you decide to take both, the practical routine is simple: add one new thing at a time and note the date you started it. If the combination is going to disagree with you, it usually shows in the first days to a couple of weeks — and a start date turns “I’ve been feeling off” into something a pharmacist can actually work with. Do not stop a prescribed medicine on your own.

Always talk with your pharmacist or doctor before making changes to your medications or supplements, particularly if you take several medications or have an ongoing health condition.

Fucus Vesiculosus safety at a glance

Fucus Vesiculosus overall Use caution Variable, high iodine content can disrupt the thyroid and the plant may concentrate heavy metals.
Pregnancy Possibly Unsafe When used orally because it may contain iodine and heavy metals; avoid using. Read the full pregnancy detail
Breastfeeding Possibly Unsafe When used orally because it may contain iodine and heavy metals; avoid using. Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center) — the full detail is in the Special populations card below. Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Mesalamine and Fucus Vesiculosus? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Mesalamine

Interactions in our licensed database are recorded against drug classes, not just single drug names. Mesalamine is filed under a single classification — oral drugs. Fucus Vesiculosus has documented interactions with 9 drug classes — the most serious being amiodarone (cordarone) (moderate), antithyroid drugs (moderate) and lithium (moderate) — and none of Mesalamine’s classifications are among them.

Classification data comes from our licensed Natural Medicines dataset. A medication can belong to classes beyond those recorded there, so this describes how the check was run — it is not a safety guarantee.

Keep it in perspective

Fucus Vesiculosus Does Interact With Other Medications

Fucus Vesiculosus has 23 moderate, 868 minor known drug interactions in our database — Mesalamine isn’t one of them. If you take anything else, check it against the full list below.

Moderate 23 Minor 868 No known interaction 1,939 (incl. Mesalamine)
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.

What to actually watch for

No Interaction Found — But Data Suggests Fucus Vesiculosus and Mesalamine May Share a Side Effect

This is not an interaction. Neither one changes how your body handles the other, and nothing here says they react together. What our sources do show is that each has separately been linked to the effects below — so taking both can make those effects more likely to turn up, and harder to pin on one or the other if they do. One of them is worth acting on rather than waiting out — marked below.

  • Kidney problems Worth acting on Additional detail

    Fucus Vesiculosus

    “A case of hemorrhagic cystitis characterized by dysuria and polyuria has been reported in a young adult who took a specific product (Slim-Kombu, Balestra and Mech) containing Fucus vesiculosus and 19 other herbal extracts orally for weight loss. Upon discontinuation, symptoms improved. It is unclear if this effect was due to Fucus vesiculosus or other ingredients in the supplement.”

    Fucus Vesiculosus · Natural Medicines adverse-effect record, reported in obesity.

    2 sources cited
    1. 46959. Catania, M. A., Oteri, A., Caiello, P., Russo, A., Salvo, F., Giustini, E. S., Caputi, A. P., and Polimeni, G. Hemorrhagic cystitis induced by an herbal mixture. South.Med.J. 2010;103(1):90-92. PubMed
    2. 12800. Conz PA, La Greca G, Benedetti P, et al. Fucus vesiculosus: a nephrotoxic alga? Nephrol Dial Transplant 1998;13:526-7.

    Mesalamine

    Listed in the ADVERSE REACTIONS section of the FDA label for Mesalamine. Read the label on DailyMed ›

Reported for Fucus Vesiculosus but not commonly for Mesalamine: an irregular heartbeat, a change in thyroid levels, a fast or pounding heartbeat and weight loss.

Effects for Mesalamine come from the ADVERSE REACTIONS section of its FDA label; effects for Fucus Vesiculosus come from the Natural Medicines adverse-effect record, quoted above. Wording is matched across sources by our own clinical vocabulary, so treat this as a prompt to pay attention, not a diagnosis.

Special populations

Fucus Vesiculosus in Pregnancy & Breastfeeding

Pregnancy And Lactation Possibly Unsafe

When used orally because it may contain iodine and heavy metals; avoid using.

DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.© 2026 Therapeutic Research Center

How to take them

Some Mesalamine Products Have a Food Rule — Fucus Vesiculosus Should Not Break It

At least one FDA label for a product containing Mesalamine says to take it with food. If you take Fucus Vesiculosus on an empty stomach out of habit, keep them separate — and take Mesalamine with a meal where the label says to.

This may not be true of your version. Food instructions belong to the product, not the ingredient: two Mesalamine products can carry different directions, and extended-release forms often differ from immediate-release ones. The label we read is quoted below — check the directions on your own box or bottle, or ask your pharmacist, for how to take the exact product you were given.

( 2 ) Administer mesalamine delayed-release tablets with food.

From the Dosage and Administration section of the FDA label we read for Mesalamine — where that label names a specific product, the instruction is that product's. Read the label on DailyMed ›

A food rule is not an interaction — it is about how much of the medicine you absorb. The directions that came with your own product, and your pharmacist, outrank anything on this page.

From our Q&A

Questions About Fucus Vesiculosus or Mesalamine

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Fucus Vesiculosus or Mesalamine, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Mesalamine

This page covers Fucus Vesiculosus only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Mesalamine page lists 17 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Coffee Charcoal (moderate), European Mandrake (moderate), Glucomannan (moderate) and Guar Gum (moderate).

By severity: 1 major · 7 moderate · 9 minor.

From our pharmacist’s overview on the Mesalamine page

“Activated charcoal is the one entry here I would treat as a genuine problem for anyone taking mesalamine (Asacol, Lialda, Pentasa, and others). It is the lone major-rated interaction among the 17 on file, because charcoal soaks up drugs in the gut and can pull mesalamine out of the picture before it does its job.”

Reviewed by 2 · Jul 18, 2026

Open the Mesalamine interaction page

How much people look this up

Where Fucus Vesiculosus and Mesalamine 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

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

29 days ago today
Medication Mesalamine
Top 10%

#282 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.

Where does our data come from?
  • Source: the Natural Medicines (TRC Healthcare) clinical database — the evidence-graded professional reference for herb & supplement interactions.
  • Citation library: 103,510 references behind our interaction content, 65,311 of them resolved to verified PubMed/DOI sources. See every Fucus Vesiculosus reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The Fucus Vesiculosus and Mesalamine records this page draws on were last updated July 10, 2026.
  • What “no known interaction” means: no documented interaction in the sources above — not a guarantee of safety. Supplements are studied far less than prescription drugs, so we say exactly what the evidence supports, and nothing more.
Data structure & sourcing designed and verified by .
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.

Fucus vesiculosus · Fucaceae · Whole plant (thallus/dried seaweed) · Capsules, tablets, powder, tea, liquid extract, topical creams and gels

An interaction check asks whether these two react with each other — it does not ask whether Fucus Vesiculosus is a good idea for someone in your situation. Here is what our Fucus Vesiculosus record says about it on its own.

Fucus Vesiculosus: dosing

There is no well-established, standardized dose for bladderwrack, partly because its iodine content varies so much from product to product. This makes safe dosing very difficult to judge.If you choose to use it, follow the directions on the product label and do not exceed them.

From our Fucus Vesiculosus monograph — the full record covers uses, side effects and every documented interaction.

Read the full Fucus Vesiculosus monograph & all interactions
Medication

About Mesalamine

What Is Mesalamine Used For?

Brand names: Pentasa, Asacol, Canasa, Rowasa, Lialda, Delzicol

Mesalamine is used to treat mildly to moderately active ulcerative colitis — a condition where the lining of the large intestine becomes inflamed and ulcerated. Depending on the product and formulation, it can be used to bring the disease under control (induction of remission) and/or to keep it from coming back (maintenance of remission).

Different products target different parts of the lower digestive tract. Oral forms (tablets and capsules) treat the colon more broadly. Rectal forms — including enemas (ROWASA, sfROWASA, mesalamine rectal suspension) — are used for distal ulcerative colitis, proctosigmoiditis, or proctitis (inflammation limited to the lower end of the colon or rectum). Rectal suppositories (CANASA, mesalamine rectal suppositories) are specifically for ulcerative proctitis (inflammation of the rectum only).

See full Mesalamine 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
868Minor
1,938No known interaction
23 Moderate 868 Minor 1,938 No interaction
Moderate

23 interactions

Minor

868 interactions

Showing 60 of 868 minor interactions — see all 868 on the Fucus Vesiculosus page.

No interaction 1,938 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 1,938 medications checked with no known interaction — see the full Fucus Vesiculosus list.

See the full Fucus Vesiculosus interactions page
See every supplement checked against Mesalamine, ranked by severity
Evidence & sources

Fucus Vesiculosus References

The 15 references that drive our Fucus Vesiculosus monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

  1. Goodman GA, Rall TW, Nies AS, Taylor P. The Pharmacological Basis of Therapeutics, 9th ed.
  2. Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington, DC: National Academy Press, 2002.
  3. Phaneuf D, Cote I, Dumas P, et al. Evaluation of the contamination of marine algae (Seaweed) from the St. Lawrence River and likely to be consumed by humans. Environ Res 1999;80:S175-S182. PubMed
  4. 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
  5. Conz PA, La Greca G, Benedetti P, et al. Fucus vesiculosus: a nephrotoxic alga? Nephrol Dial Transplant 1998;13:526-7.
  6. Ohye H, Fukata S, Kanoh M, et al. Thyrotoxicosis caused by weight-reducing herbal medicines. Arch Intern Med 2005;165:831-4. PubMed
  7. Okamura K, Inoue K, Omae T. A case of Hashimoto's thyroiditis with thyroid immunological abnormality manifested after habitual ingestion of seaweed. Acta Endocrinol (Copenh) 1978;88:703-12. PubMed
  8. Agarwal SC, Crook JR, Pepper CB. Herbal remedies -- how safe are they? A case report of polymorphic ventricular tachycardia/ventricular fibrillation induced by herbal medication used for obesity. Int J Cardiol 2006;106:260-1. PubMed
  9. Sterling JB, Heymann WR. Potassium iodide in dermatology: a 19th century drug for the 21st century-uses, pharmacology, adverse effects, and contraindications. J Am Acad Dermatol 2000;43:691-7. PubMed
  10. Catania, M. A., Oteri, A., Caiello, P., Russo, A., Salvo, F., Giustini, E. S., Caputi, A. P., and Polimeni, G. Hemorrhagic cystitis induced by an herbal mixture. South.Med.J. 2010;103(1):90-92. PubMed
  11. 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
  12. 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
  13. Arbaizar, B. and Llorca, J. [Fucus vesiculosus induced hyperthyroidism in a patient undergoing concomitant treatment with lithium]. Actas Esp.Psiquiatr. 2011;39(6):401-403.
  14. 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
  15. 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.

Medication overviews come from MedlinePlus (NIH); supplement label data from the NIH Dietary Supplement Label Database. Content is written and reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

Pharmacist Counseling Corner

Taking Fucus Vesiculosus and Mesalamine Together: Common Questions

Is it safe to take Fucus Vesiculosus with Mesalamine?
We do not list a known interaction between Fucus Vesiculosus and Mesalamine. That does not guarantee the combination is risk-free, so confirm with your pharmacist or doctor — especially if you take other medications or have a health condition.
Do Fucus Vesiculosus and Mesalamine have any of the same side effects?
Yes — our sources link each of them separately to one of the same effects. That is not an interaction: neither changes how your body handles the other. It does mean that if one of those effects turns up, it can be harder to tell which one is behind it. They are listed on this page with the source behind each.
Should I take Fucus Vesiculosus and Mesalamine at the same time of day?
At least one FDA label for a product containing Mesalamine says to take it with food. If you take Fucus Vesiculosus on an empty stomach out of habit, keep them separate and take Mesalamine with a meal where the label says to. Food instructions belong to the product rather than the ingredient — two Mesalamine products can differ — so check the directions on your own box. This is about absorption, not an interaction.
How was the Fucus Vesiculosus and Mesalamine combination checked?
Interactions in our licensed database are recorded against drug classes. Mesalamine is filed under 1 classification, and Fucus Vesiculosus has documented interactions with 9 drug classes — none of Mesalamine's classifications are among them. A medication can belong to classes beyond those recorded in our dataset, so this describes how the check was run rather than guaranteeing safety.
Does Fucus Vesiculosus interact with any other medications?
Yes. Fucus Vesiculosus has 891 documented drug interactions in our database — Mesalamine is simply not one of them. If you take anything else, it is worth checking each one; they are all listed on this page.
Does Mesalamine interact with any supplements?
Yes. Mesalamine has documented interactions with 17 supplements in our database — Fucus Vesiculosus is not one of them. The Mesalamine interaction page linked on this page lists every one, ranked by severity.

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

Where next

Keep Exploring

Fucus Vesiculosus monograph Uses, safety profile, and every drug interaction in one place Mesalamine drug information The full plain-English guide to this medication Mesalamine supplement interactions Every supplement checked against Mesalamine, ranked by severity Supplement interaction checker Check any supplement or product against your medications Browse medications A–Z Every drug we’ve checked against herbs & supplements References The 15 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Mesalamine and Fucus Vesiculosus?

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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.