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Dietary supplement

Full Spectrum Bladderwrack 500 mg Ingredients & Drug Interactions

by Swanson Premium Brand

Full Spectrum Bladderwrack 500 mg label
See full label image
Capsule Category: Non-nutrient/non-botanical
Most serious interaction: Moderate
Clinical methodology reviewed by · Updated Sep 16, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking Full Spectrum Bladderwrack 500 mg against your medications. The heart of this page is the interaction checker and the full interaction report — how this product’s ingredients may interact with prescription and over-the-counter medicines you may be taking.

Around that, we add a pharmacist’s high-level view of the product as a whole — what’s inside, the evidence for its stated use, how transparent the label is, and what safety data exists — so you can see the full picture in one place. It’s educational information from our licensed clinical databases and the clinical staff at HelloPharmacist — not medical advice — and we don’t sell or endorse products. Our editorial policy

The interaction bottom line Most serious interaction: Moderate

Full Spectrum Bladderwrack 500 mg is a dietary supplement by Swanson Premium Brand with 1 active ingredient. Its ingredients are commonly taken for thyroid support, iodine source, weight management.Based on those ingredients, 891 medications have a known interaction with it, the most serious rated moderate. The ingredients most likely to interact are Bladderwrack. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

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Check Your Meds Against Full Spectrum Bladderwrack 500 mg by Swanson Premium Brand

Ask about any prescription or over-the-counter medication and we check it for interactions with Full Spectrum Bladderwrack 500 mg by Swanson Premium Brand — and tell you which ingredient is responsible.

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HelloPharmacist Scorecard of Full Spectrum Bladderwrack 500 mg by Swanson Premium Brand

Our pharmacy team’s full take, with four database checks built into the cards below — a summary of what is known, not a grade of the product itself.

From our pharmacy team — supplement deep dive

Generated from HelloPharmacist’s pharmacist-curated databases and editorial rules · Last generated Jul 11, 2026

What’s inside

Full disclosure
Ingredient Transparency · database check
Full

Every active ingredient lists its own amount on the label.

Why this rating?
  • The label discloses an exact amount for 1 of its 1 active ingredient.
  • No proprietary blends here — you can verify the dose of every single component.

This supplement contains one active ingredient: bladderwrack (a type of seaweed, scientifically known as Fucus vesiculosus), at 500 mg per capsule. Bladderwrack is a marine plant that naturally contains very high levels of iodine, along with other compounds like fucoidan.

The capsule itself is made from gelatin and brown rice flour.

Does it work?

Couldn't assess
Evidence for Intended Use · database check
By FDA rules, dietary supplements can’t claim to treat, cure, or prevent disease — so labels speak in careful marketing language. We discern each product’s intended use from its name, label claims, and label statements, then grade the clinical evidence for that use. How these ratings are computed
Not assessable

This is a single-ingredient Fucus Vesiculosus product and its label doesn't state a use — see Fucus Vesiculosus's own graded uses on its monograph.

Why this rating?
  • We looked at the product name, claims, and label statements and couldn't find a stated purpose to grade.

The evidence for bladderwrack is limited. Our data shows insufficient reliable evidence to rate it for aging skin, heart health, constipation, diarrhea, or indigestion.

That doesn't mean it doesn't work — it means the studies we have don't yet establish whether it does.

The evidence, ingredient by ingredient Fucus Vesiculosus

How safe is it?

Well-documented data
Safety Information · database check
Well characterized

Adverse-effect, pregnancy, and general safety data are on file for most of these ingredients.

Why this rating?
  • We hold adverse-effect (side-effect) data for 1 of the 1 matched ingredient.
  • Pregnancy & breastfeeding safety ratings cover 1 of 1.
  • General safety write-ups exist for 1 of 1.
  • Remember: this measures how much safety information exists. Thin data is not the same as being safe.

When taken by mouth, bladderwrack raises real safety concerns because of its iodine content and the fact that seaweed can absorb heavy metals from ocean water. The most common side effects are goiter (swollen thyroid), overactive thyroid, and underactive thyroid.

Rarely, it's been linked to thyroid cancer. There's also a case of a person taking a bladderwrack-containing weight loss supplement who developed heart palpitations and abnormal heart rhythm, though it's unclear whether bladderwrack alone was responsible.

Because of the iodine and possible heavy metals, bladderwrack is not advised during pregnancy or while breastfeeding — iodine passes into breast milk and can affect your baby's thyroid.

Side effects, ingredient by ingredient Fucus Vesiculosus

Meds to double-check

Moderate interaction found
Known Interaction Concern · database check
Moderate identified

The most serious documented interaction for these ingredients is Moderate. Check your medications for a personalized result.

Why this rating?
  • 1 of the 1 matched ingredient can interact with medications — Fucus Vesiculosus.
  • The most serious interaction on file is rated Moderate.
  • Some involve high-stakes drug classes: anticoagulant / antiplatelet drugs; lithium.
  • For scale: 892 individual medications appear in the full list. A big number alone doesn't make a product dangerous — what matters is whether YOUR medication is on it, so run yours through the interaction checker on this page.

Check with us first if you take lithium, any thyroid medications (including antithyroid drugs or hormone replacements), amiodarone, blood thinners or antiplatelet drugs, or any medication broken down by your liver — including many heart, pain, and psychiatric medications. The interactions with thyroid and lithium are the most serious.

Check your own medication Run your meds through the checker above

The bottom line

Scorecard at a glanceFully disclosed formula with no assessable stated purpose. Moderate medication interactions have been identified, and safety information is well characterized.

If you have a thyroid condition, take any thyroid medication, or use lithium, talk to your pharmacist or doctor before trying this. Even if you don't take those drugs, your thyroid function can shift because of bladderwrack's iodine content.

This is a supplement where the risks are well documented and the benefits are not — ask us before you start.

Educational only — not medical advice; always confirm with your pharmacist. Our editorial policy · How we use AI

Assessment coverage: 1 of 1 active ingredient matched to our full ingredient reviews (monographs). Based on the product label dated Feb 25, 2019.

This Scorecard evaluates available label information, ingredient evidence, and known medication-safety considerations. It does not independently verify product identity, purity, potency, contamination, or manufacturing quality. How these ratings are computed

At a glance

General information

Key facts about Full Spectrum Bladderwrack 500 mg, straight from the product label.

Brand Swanson Premium Brand
Barcode (UPC) 087614113999
Net contents 60 Capsule(s)
Market status On market
Date entered into DSLD Feb 25, 2019
DSLD ID 193242
Product type Non-nutrient/non-botanical
Supplement form Capsule
Dietary claims / uses All Other
Intended target group(s) Adult (18 - 50 Years)
From the label
Everything in this section is reproduced from the manufacturer’s own product label — it’s the label speaking, not HelloPharmacist. We show it so you can see exactly what the maker states; we don’t verify or endorse those statements.

Supplement Facts

The label details for Full Spectrum Bladderwrack 500 mg by Swanson Premium Brand, sourced from the NIH Dietary Supplement Label Database.

Supplement Facts

Daily Value (DV) Target Group(s):
Adults and children 4 or more years of age
Minimum serving Sizes:
1 Capsule(s)
Maximum serving Sizes:
1 Capsule(s)
UPC/BARCODE
087614113999
IngredientAmount% DV
Bladderwrack500 mg--

Other ingredients: Gelatin, Brown Rice Flour, May contain one or both of the following

Tap any ingredient to jump to its full detail below.

Label statements
These statements are the manufacturer’s wording, reproduced from the product label — the label is saying it, not HelloPharmacist. We don’t verify or endorse them.
General Statements

Bringing wellness to the world since 1969

To reorder, call toll free 1-800-437-4148 or visit our website at www.swansonvitamins.com

FDA Statement of Identity

Herbal Supplement

Seals/Symbols

Guaranteed purity & potency

Precautions

Do not use if seal is broken.

Keep out of reach of children.

Warning: Consult your healthcare provider before use if you are pregnant or nursing, taking prescription medication or if you have a medical condition.

Do not exceed recommended dosage.

Storage

Store in a cool, dry place.

Suggested/Recommended/Usage/Directions

Suggested use: As a dietary supplement, take one capsule per day with water.

General

SW1399 Rev 0 08 06 18

Is this label outdated? Report a formula or label change and our pharmacy team will review it.

See for yourself

Full Spectrum Bladderwrack 500 mg by Swanson Premium Brand label

The label scan from the NIH Dietary Supplement Label Database. Tap to enlarge.

Full Spectrum Bladderwrack 500 mg label

Label images are published by the NIH Dietary Supplement Label Database for the version of this product on file. Always read your actual product label.

View the full label (PDF)
What’s inside

The Ingredients in Full Spectrum Bladderwrack 500 mg by Swanson Premium Brand

This is the 1 active ingredient this product is made of. Select it to open its full monograph.

Serving size1 Capsule(s) Dosage formCapsule Amounts shown are per serving.

Bladderwrack

Interacts with
891 drugs
500 mg per serving

Fucus vesiculosus (bladderwrack) is a brown seaweed rich in iodine that has been used traditionally for thyroid concerns, weight, and skin. There is l...

Bladderwrack monograph & interactions

Other (inactive) ingredients: Gelatin, Brown Rice Flour, May contain one or both of the following. These complete the product’s ingredient list but are not active constituents.

Interaction report

Full Spectrum Bladderwrack 500 mg by Swanson Premium Brand Drug Interactions

Want to check YOUR meds against Full Spectrum Bladderwrack 500 mg?

Ask about interactions with your drugs in plain English — “Can I take it with lisinopril?” — and we find you the answer in seconds, ingredient by ingredient.

 Go to the checker
891Drugs
23 Moderate 868 Minor

Ingredients driving the most interactions

Bladderwrack 891

Individual Drug Interactions

The ingredients in Full Spectrum Bladderwrack 500 mg interact with 891 drugs. Click any drug to see the details.

1 of the 1 ingredient in Full Spectrum Bladderwrack 500 mg interact with drugs. Each result below shows which ingredient is responsible. Bladderwrack

Each ingredient & the kinds of drugs it affects

For each ingredient in Full Spectrum Bladderwrack 500 mg with known interactions, here are the types of medications it can affect. Open any type for the detail — or search your exact drug in the checker above.

Bladderwrack9 drug types · 891 drugs

Amiodarone (Cordarone)

Theoretically, combining Fucus vesiculosus with amiodarone might cause excessively high iodine levels.
Fucus vesiculosus contains high concentrations of iodine. Amiodarone contains 37.3% iodine and can increase iodine levels. Concomitant use might increase the risk of having excessive iodine levels and adversely affecting thyroid function. Monitor thyroid function.

Likelihood Probable Evidence D
Antithyroid Drugs

Due to its iodine content, Fucus vesiculosus might alter the effects of antithyroid drugs.
Fucus vesiculosus contains high concentrations of iodine. Iodine in high doses has been reported to cause both hyperthyroidism and hypothyroidism, depending on the individual's past medical history. Taking Fucus vesiculosus while using antithyroid drugs could alter the effects of the antithyroid drugs.

Likelihood Possible Evidence D
Lithium

Concomitant use of Fucus vesiculosus and lithium has resulted in hyperthyroidism.
There is a case of hyperthyroidism occurring in a patient taking Fucus vesiculosus and lithium. Monitor thyroid hormones closely in patients taking lithium and Fucus vesiculosus concomitantly.

Likelihood Possible Evidence D
Thyroid Hormone

Due to its iodine content, Fucus vesiculosus might alter the effects of thyroid hormone.
Fucus vesiculosus contains high concentrations of iodine. Iodine in high doses has been reported to cause both hyperthyroidism and hypothyroidism, depending on the individual's past medical history. Taking Fucus vesiculosus while using thyroid hormone could alter the effects of thyroid hormone.

Likelihood Possible Evidence D
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.

Likelihood Unlikely Evidence D
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.

Likelihood Possible Evidence D
Cytochrome P450 2C9 (Cyp2C9) Substrates

Theoretically, concomitant use of Fucus vesiculosus with CYP2C9 substrates might increase the risk for adverse effects.
In vitro research shows that fucoidan, a constituent of Fucus vesiculosus, inhibits CYP2C9. This interaction has not been reported in humans.

Likelihood Possible Evidence D
Cytochrome P450 2D6 (Cyp2D6) Substrates

Theoretically, concomitant use of Fucus vesiculosus with CYP2D6 substrates might alter the effects of these substrates.
In vitro research shows that fucoidan, a constituent of Fucus vesiculosus, both inhibits and induces CYP2D6. This interaction has not been reported in humans.

Likelihood Possible Evidence D
Cytochrome P450 3A4 (Cyp3A4) Substrates

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.

Likelihood Possible Evidence D
Bladderwrack full monograph & interactions
The maker

Brand information

Manufacturer and brand details for Full Spectrum Bladderwrack 500 mg, from the product label.

Swanson Premium Brand

See all Swanson Premium Brand products
Name
Swanson Health Products
City
Fargo
State
ND
ZipCode
58104
Phone Number
1-800-437-4148
Web Address
www.swansonvitamins.com
Pharmacist Counseling Corner

Full Spectrum Bladderwrack 500 mg by Swanson Premium Brand: Common Questions

Does Full Spectrum Bladderwrack 500 mg by Swanson Premium Brand interact with any medications?
Yes. Based on its ingredients, Full Spectrum Bladderwrack 500 mg has a known interaction with 891 medications. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
Full Spectrum Bladderwrack 500 mg contains a single active ingredient, and that one ingredient can interact with many different medications on its own. We check it against each medication and show the mechanism responsible.
Where does this information come from?
The product label data comes from the NIH Dietary Supplement Label Database (DSLD); the interaction data is built on the Natural Medicines database and reviewed by HelloPharmacist pharmacists.
Is bladderwrack safe to take while I'm pregnant or breastfeeding?
No. The safety data advises against it. The high iodine content and potential heavy metals make it unsafe in pregnancy, and iodine passes into breast milk and may affect your baby's thyroid, so it should be avoided while breastfeeding.
What are the most common side effects?
The most common ones are related to the thyroid — goiter (a swollen thyroid), overactive thyroid, and underactive thyroid. These happen because bladderwrack is so high in iodine. Serious side effects are rare but can include thyroid cancer.
Can I take this if I'm on thyroid medication?
You need to talk to your pharmacist or doctor first. Bladderwrack's iodine can change how thyroid medications work — it may boost or reduce their effects depending on your health history and which medication you take. This is one of the main interaction concerns.
What is bladderwrack used for?
It's marketed for aging skin, heart health, constipation, diarrhea, and indigestion, but we don't have enough reliable evidence to say it actually works for any of these. The data is simply insufficient to rate its effectiveness.
Why does this supplement interact with so many medications?
The main reason is bladderwrack's very high natural iodine content, which affects your thyroid and can interfere with thyroid drugs, lithium, and heart medications like amiodarone. Additionally, a compound in it called fucoidan may slow how your liver breaks down certain drugs, though this hasn't been proven in people yet.
What does 'full spectrum' mean on the label?
That term means the product contains the whole plant (or a broader extract of it) rather than a single isolated compound. In this case, you're getting the whole bladderwrack with all its naturally occurring iodine and other constituents.

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

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Label information is sourced from the NIH Dietary Supplement Label Database and reflects the product version on file; always read your actual product label. This page is for education only and is not a substitute for professional medical advice. Confirm with your pharmacist or doctor before combining supplements and medications.

Full Spectrum Bladderwrack 500 mg label
Go deeper

The Full Monographs Behind Full Spectrum Bladderwrack 500 mg’s Ingredients

Every ingredient we hold a full HelloPharmacist monograph for — uses, evidence, safety, and the complete interaction list.

Herb & supplement monograph

Fucus Vesiculosus

Interacts with 891 drugs

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 mo...

Read the full Fucus Vesiculosus monograph →
Sources

Sources & How We Checked

Full Spectrum Bladderwrack 500 mg's label data comes from the NIH Dietary Supplement Label Database; the ingredient interaction data is from the Natural Medicines database, reviewed by our pharmacists.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

The 15 references behind this product’s interaction data

Every citation that drives the interaction findings for this product’s ingredients, from the evidence-graded Natural Medicines (TRC Healthcare) database. Open an ingredient to browse its citations — links open the study on PubMed or the publisher’s site.

Fucus Vesiculosus 15 references
  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.

See these in context on the Fucus Vesiculosus monograph →

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

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