Identity & origin
BOTANICAL IDENTITY
The right name is the first step.
A brown seaweed whose fronds bear gas-filled bladders.
Also known as: No synonyms listed.
The thallus is the seaweed's vegetative body. Its iodine content distinguishes its preparations from an ordinary herbal tea. A photograph alone cannot certify a plant for consumption.
An illustration is not enough to identify a plant for consumption. Do not forage for a species based solely on this profile.
Uses & evidence
UNDERSTANDING THE USES
Properties & uses.
Restricted traditional use
EMA describes adjunctive use with a calorie-controlled diet in overweight adults after medical exclusion of serious causes.
Use considered plausible in a traditional-use monograph. That status alone does not demonstrate clinical efficacy.
Read the sourceThe traditional uses described are not clinical proof of effectiveness. Evidence for one preparation cannot automatically be applied to another.
Precautions before use
BEFORE ANY USE
Precautions & contraindications.
This guidance does not cover every individual situation. Missing information is not a guarantee of safety.
The following warnings do not constitute a complete review of interactions or contraindications. An unstudied combination cannot be considered compatible.
Contraindications & precautions
- Avoid if allergic to this plant. The sources for this profile do not provide a complete contraindication assessment.
Medicine interactions
- Do not combine with iodine preparations or thyroid medication.
“Reported” does not prove causality; “possible” may reflect indirect evidence. “None reported” means none in the cited source, not that all combinations have been studied. Do not stop a prescribed treatment based on this profile.
Adverse effects
- The selected sources do not establish the frequency of adverse effects.
Pregnancy & breastfeeding
Safety information is insufficient to recommend medicinal use during pregnancy or breastfeeding.
Children & adolescents
The monograph concerns adults only; no paediatric preparation.
If symptoms persist, worsen or are unusual, consult a healthcare professional. In an emergency, contact the emergency services.
Forms & how they are used
DOCUMENTED FORMS
One plant, several preparations.
Only forms documented in this profile’s sources are presented.
Powdered thallusDried thallus · Route: Oral
Solid forms considered by EMA; concentrations are not interchangeable.
Please note: Do not combine with iodine preparations or thyroid medication.
Read the sourceAvailable evidence
EXPLORE THE EVIDENCE
The available evidence.
EMA recognises traditional adjunctive use in weight management, without sufficiently demonstrated clinical efficacy.
Constituents to know.
Their presence and quantity depend on the plant part and preparation.
- Iodine
- Content requires control; excess can be toxic.Read the reference
- Polysaccharides
- Alginate, laminarin and fucoidan are described in the report; their presence alone does not validate benefit.Read the reference
Action and scope
Recognition rests on longstanding use, not a slimming effect established by robust trials.
Use considered plausible in a traditional-use monograph. That status alone does not demonstrate clinical efficacy.
Read the referenceLimitations to keep in mind.
Do not improvise a seaweed regimen: iodine exposure must be considered.
Studies, findings & limitations
THE RESEARCH
What the research shows.
A laboratory or animal result alone does not demonstrate a benefit in humans. Each result must be read alongside the preparation studied and its limitations.
EMA — Fucus: herbal summary
Use considered plausible in a traditional-use monograph. That status alone does not demonstrate clinical efficacy.
- Type of research
- Herbal medicinal products committee assessment.
- Preparation concerned
- Dried, powdered thallus in solid oral forms.
- Observed results
- Available studies cannot establish a clinical benefit attributable to fucus itself.
- Limitations to consider
- Adults only; dietary context and medical causes require assessment.
What can we take from this?
Adults only; dietary context and medical causes require assessment.
Documentary review dated 09/10/2026. The references remain available to check the context.
Sources & last review
CHECKING REFERENCES
Sources for this profile.
- ANSM — Liste A, janvier 2026, page 16Accessed on 09/10/2026
- EMA — Fucus: herbal summaryAccessed on 09/10/2026
- EMA — Assessment report on Fucus vesiculosus L., thallusAccessed on 09/10/2026
Image: W.carter · CC0. View the original image and its licence. Image resized and converted to WebP.