Herb & supplement monograph
Sea Moss Drug Interactions, Uses, Effectiveness, Safety & More
What is this page for?
First and foremost: how Sea Moss interacts with medications. The heart of this page is the interaction list — every drug Sea Moss is known to interact with, and how serious each one is.
But these pages have grown well beyond that into a full monograph — what Sea Moss is, what people use it for and how strong the evidence is, its safety and side effects, and answers to the questions we’re asked most — written and reviewed by the clinical staff at HelloPharmacist. It’s educational information from our licensed clinical databases, not medical advice, and we don’t sell or endorse products. Our editorial policy
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Interaction report
Drugs that interact with Sea Moss
22 medications have a known interaction with Sea Moss, graded by severity. Select any drug for the full evidence-based detail.
Don’t want to scroll the list? Just ask.
Tell us the medications you take and we’ll check each one against Sea Moss using our pharmacist-reviewed interaction data.
AI summaries are generated from our Sea Moss interaction data for education only — always confirm with your pharmacist. How we use AI
2,830 drugs
No drugs match “”.
AmiodaroneCordarone, Pacerone
Moderate
Amiodarone (cordarone)
Theoretically, combining sea moss with amiodarone might cause excessively high iodine levels.
Read the full Sea Moss + Amiodarone interaction Amiodarone drug page: uses, dosage & side effectsCarbimazoleNeo-Mercazole
Moderate
Antithyroid Drugs
Due to its iodine content, sea moss might alter the effects of antithyroid drugs.
Read the full Sea Moss + Carbimazole interactionConjugated EstrogensCenestin, Enjuvia, Premarin, Premarin Vaginal Cream
Moderate
Thyroid Hormone
Due to its iodine content, sea moss might alter the effects of thyroid hormone.
Read the full Sea Moss + Conjugated Estrogens interactionDesiccated Thyroid ExtractWesthroid, WP Thyroid
Moderate
Thyroid Hormone
Due to its iodine content, sea moss might alter the effects of thyroid hormone.
Read the full Sea Moss + Desiccated Thyroid Extract interactionDesiccated Thyroid Extract (prescription Drug)Nature-Throid, Thyrar
Moderate
Thyroid Hormone
Due to its iodine content, sea moss might alter the effects of thyroid hormone.
Read the full Sea Moss + Desiccated Thyroid Extract (prescription Drug) interactionDextrothyroxineCholoxin
Moderate
Thyroid Hormone
Due to its iodine content, sea moss might alter the effects of thyroid hormone.
Read the full Sea Moss + Dextrothyroxine interactionHuman Chorionic Gonadotropin (hcg)Pregnyl
Moderate
Thyroid Hormone
Due to its iodine content, sea moss might alter the effects of thyroid hormone.
Read the full Sea Moss + Human Chorionic Gonadotropin (hcg) interactionLevothyroxineEltroxin, Estre, Euthyrox, Levo-T, Levolet, Levothroid +5 more
Moderate
Thyroid Hormone
Due to its iodine content, sea moss might alter the effects of thyroid hormone.
Read the full Sea Moss + Levothyroxine interaction Levothyroxine drug page: uses, dosage & side effectsLevothyroxine SodiumErmez, Thyquidity, Tirosint-Sol
Moderate
Thyroid Hormone
Due to its iodine content, sea moss might alter the effects of thyroid hormone.
Read the full Sea Moss + Levothyroxine Sodium interactionLevothyroxine, LiothyronineArmour Thyroid
Moderate
Thyroid Hormone
Due to its iodine content, sea moss might alter the effects of thyroid hormone.
Read the full Sea Moss + Levothyroxine, Liothyronine interactionLiothyronineCytomel
Moderate
Thyroid Hormone
Due to its iodine content, sea moss might alter the effects of thyroid hormone.
Read the full Sea Moss + Liothyronine interaction Liothyronine drug page: uses, dosage & side effectsLiotrixEuthroid 1, Euthroid 1/2, Euthroid 3
Moderate
Thyroid Hormone
Due to its iodine content, sea moss might alter the effects of thyroid hormone.
Read the full Sea Moss + Liotrix interaction Liotrix drug page: uses, dosage & side effectsLiotrix, T4/t3Euthroid 2
Moderate
Thyroid Hormone
Due to its iodine content, sea moss might alter the effects of thyroid hormone.
Read the full Sea Moss + Liotrix, T4/t3 interactionMenotropinsMenopur, Repronex
Moderate
Thyroid Hormone
Due to its iodine content, sea moss might alter the effects of thyroid hormone.
Read the full Sea Moss + Menotropins interactionMethenamine MandelateMandelamine, Methimazole
Moderate
Antithyroid Drugs
Due to its iodine content, sea moss might alter the effects of antithyroid drugs.
Read the full Sea Moss + Methenamine Mandelate interaction Methenamine Mandelate drug page: uses, dosage & side effectsMethimazoleTapazole
Moderate
Antithyroid Drugs
Due to its iodine content, sea moss might alter the effects of antithyroid drugs.
Read the full Sea Moss + Methimazole interaction Methimazole drug page: uses, dosage & side effectsOspemifeneOsphena
Moderate
Thyroid Hormone
Due to its iodine content, sea moss might alter the effects of thyroid hormone.
Read the full Sea Moss + Ospemifene interaction Ospemifene drug page: uses, dosage & side effectsPotassium Iodide (prescription Drug)Thyro-Block
Moderate
Antithyroid Drugs
Due to its iodine content, sea moss might alter the effects of antithyroid drugs.
Read the full Sea Moss + Potassium Iodide (prescription Drug) interactionPropylthiouracil, PtuPropylthiouracil
Moderate
Antithyroid Drugs
Due to its iodine content, sea moss might alter the effects of antithyroid drugs.
Read the full Sea Moss + Propylthiouracil, Ptu interaction Propylthiouracil, Ptu drug page: uses, dosage & side effectsTestosterone UndecanoateAndriol, Aveed, Jatenzo, Kyzatrex
Moderate
Thyroid Hormone
Due to its iodine content, sea moss might alter the effects of thyroid hormone.
Read the full Sea Moss + Testosterone Undecanoate interaction Testosterone Undecanoate drug page: uses, dosage & side effectsThyroglobulinProloid
Moderate
Thyroid Hormone
Due to its iodine content, sea moss might alter the effects of thyroid hormone.
Read the full Sea Moss + Thyroglobulin interactionThyroid HormoneEtwon
Moderate
Thyroid Hormone
Due to its iodine content, sea moss might alter the effects of thyroid hormone.
Read the full Sea Moss + Thyroid Hormone interaction
Read The List Like a Pharmacist
What Severity, Likelihood & Evidence Mean
Severity — How Serious It Can Be
- Major. Clinically significant; generally best avoided, or used only under direct professional supervision.
- Moderate. May need monitoring, a dose adjustment, or separating the times you take each one.
- Minor. Generally not clinically significant, but still worth noting and mentioning to your pharmacist.
- No known interaction. Checked against our sources with nothing documented — not the same as proven safety.
Likelihood — How Well It’s Documented
- Likely. Well-controlled human studies have demonstrated the likely existence of this interaction
- Probable. Interaction 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.
- Possible. 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
- Unlikely. Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Where This Data Comes From
- Interaction records are evidence-graded and sourced from the Natural Medicines database (TRC Healthcare), the same reference used by pharmacists and hospitals.
- Each drug listed above links to the full report for that exact Sea Moss combination — clinical detail, likelihood, evidence level, and citations.
- Content is reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.
The big picture
The kinds of drugs Sea Moss affects
Every type of medication (drug category) Sea Moss is known to interact with. Open any category for the detail — or search your exact drug in the checker above.
All 3 drug categories Sea Moss interacts with
Amiodarone (cordarone)Antithyroid DrugsThyroid Hormone
Amiodarone (Cordarone)
Theoretically, combining sea moss with amiodarone might cause excessively high iodine levels.
Amiodarone contains 37.3% iodine and can increase iodine levels. Concomitant use with sea moss, which contains approximately 4-7 mcg of iodine per gram, might increase the risk of adverse effects from iodine, including altered thyroid function.
Antithyroid Drugs
Due to its iodine content, sea moss might alter the effects of antithyroid drugs.
Sea moss contains approximately 4-7 mcg of iodine per gram. Iodine in high doses has been reported to cause both hyperthyroidism and hypothyroidism, depending on the individual's past medical history. Taking sea moss could theoretically alter the effects of antithyroid drugs.
Thyroid Hormone
Due to its iodine content, sea moss might alter the effects of thyroid hormone.
Sea moss contains approximately 4-7 mcg of iodine per gram. Iodine in high doses has been reported to cause both hyperthyroidism and hypothyroidism, depending on the individual's past medical history. Taking sea moss could theoretically alter the effects of thyroid hormone.
Monograph
Sea Moss: Uses, Safety & Side Effects
The bottom line
Sea moss is a type of red seaweed that is naturally rich in iodine and several minerals, and it is popular as a 'whole-food' supplement. Strong human evidence for most of its health claims is lacking, and its high and variable iodine content can be a real concern, especially for people with thyroid problems. Talk to your pharmacist or doctor before using it, particularly if you are pregnant, breastfeeding, or have a thyroid condition.
- Scientific name
- Chondrus crispus
- Family
- Gigartinaceae
- Part used
- Whole dried seaweed (thallus)
- Common forms
- Gel, dried raw seaweed, capsules, powder, gummies, drinks, skin products
People commonly use it for
- Source of iodine and minerals
- Thyroid support
- Respiratory issues and cough
- Digestive support
- Skin and hair health
- General immune and antioxidant support
Popular and traditional uses — not proof it works. See “Uses & effectiveness” below for the evidence.
OverallUse caution
Generally seen as food, but variable iodine levels and possible heavy-metal content warrant caution.
PregnancyLikely Safe
When used in food amounts. There is insufficient reliable information available about the safety of using larger amounts; avoid using.
Read the full pregnancy detailBreastfeedingLikely Safe
When used in food amounts. There is insufficient reliable information available about the safety of using larger amounts; avoid using.
Read the full breastfeeding detailPregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center). Safety guidance is general; always confirm with your pharmacist or doctor for your situation.
Overview
Sea moss, often called Irish moss, is a red seaweed (Chondrus crispus) that grows along the rocky Atlantic coasts of Europe and North America. People have harvested it for centuries, and it has long been used in foods as a natural thickener because it contains carrageenan.
Today it is heavily promoted on social media as a 'superfood.' It is sold as a homemade or store-bought gel, dried seaweed, powder, capsules, and gummies, and it is added to smoothies, teas, and skin care products. Fans value it as a plant-based source of iodine, minerals, and antioxidants.
How it works
Sea moss naturally contains iodine, a mineral the body needs to make thyroid hormones. It also provides smaller amounts of other minerals and some fiber-like compounds called carrageenans, along with plant antioxidants.
The proposed benefits are mostly based on these nutrients and on laboratory or animal studies. For example, carrageenan and other seaweed compounds have shown gel-forming, soothing, and antioxidant effects in the lab. However, how much of this translates into real benefits in humans is not well established, and the iodine content is the part most likely to have a true effect on the body.
Effectiveness
Does Sea Moss work?
Evidence overview · 5 uses evaluated
5 Insufficient evidence
How to read these evidence grades
Natural Medicines’ 7-point scale. We show each rating’s label word-for-word.
1EffectiveStrong, consistent evidence it works.
2Likely EffectiveGood evidence, though not yet conclusive.
3Possibly EffectiveSome evidence suggests a benefit.
4Possibly IneffectiveSome evidence it may not help.
5Likely IneffectiveFairly strong evidence it doesn’t help.
6IneffectiveStrong evidence it doesn’t work.
7Insufficient Reliable Evidence to RateToo little research to say either way.
For Sea Moss, current evidence isn’t strong enough to rate any specific use. The conditions it has been studied for are listed below.
Also studied for 5 conditions — evidence insufficient to rate
Insufficient Reliable Evidence To Rate Fatigue
Rating & evidence shown verbatim from Natural Medicines
It is unclear if oral sea moss is beneficial for increasing energy.
Insufficient Reliable Evidence To Rate Iodine deficiency
Rating & evidence shown verbatim from Natural Medicines
Although there is interest in using oral sea moss as a source of iodine, there is insufficient reliable information about the clinical effects of sea moss for this use.
Insufficient Reliable Evidence To Rate Muscle strength
Rating & evidence shown verbatim from Natural Medicines
Although there is interest in using oral sea moss for muscle support in athletes, there is insufficient reliable information about the clinical effects of sea moss for this use.
Insufficient Reliable Evidence To Rate Pain (chronic)
Rating & evidence shown verbatim from Natural Medicines
It is unclear if oral sea moss is beneficial for pain reduction.
Insufficient Reliable Evidence To Rate Quality of life
Rating & evidence shown verbatim from Natural Medicines
It is unclear if oral sea moss is beneficial for improving quality of life.
Source & disclaimer. Effectiveness ratings and evidence summaries are provided by Natural Medicines (Therapeutic Research Center) and shown as licensed. Where Natural Medicines hasn’t rated a use, HelloPharmacist’s pharmacists may add their own reviewed rating and evidence (each such entry is labeled). This is educational information, not medical advice — talk with your pharmacist or doctor before starting, stopping, or changing a supplement.
Safety & precautions
Sea moss is eaten as a food in some cultures, but using it as a daily supplement raises a few real concerns. The biggest is iodine: the amount in sea moss is high and can vary a lot from batch to batch. Too much iodine can disturb thyroid function, causing either an underactive or overactive thyroid. People with thyroid disease should be especially careful and check with their doctor first.
Seaweed can also absorb heavy metals such as arsenic, lead, and mercury from seawater, so quality and sourcing matter. Choose products from reputable companies that test for contaminants.
Pregnancy and breastfeeding: Because iodine intake and contaminant levels are hard to control, it is best to avoid sea moss supplements during pregnancy and while breastfeeding unless your doctor specifically advises otherwise.
Side effects
For most people, small food amounts are usually well tolerated. Possible side effects include digestive upset, bloating, or loose stools, partly due to its fiber-like compounds.
More serious problems are usually tied to excess iodine, which can cause thyroid changes, neck swelling (goiter), a metallic taste, or symptoms of an overactive or underactive thyroid. Rarely, people may have an allergic reaction. Long-term use of high amounts could also expose you to heavy metals. Stop using it and seek care if you notice swelling, trouble breathing, or other concerning symptoms.
Sea Moss: Reported Adverse Effects
Documented safety reports on Sea Moss from the evidence-graded Natural Medicines (TRC Healthcare) database, shown word-for-word from the licensed record.
Reports by conditionConstipation Gastrointestinal
Orally, see moss has been reported to cause constipation and diarrhea in one observational study.
- Palmieri B, Vadalà M, Laurino C. Clinical effects of overwintered-stressed Chondrus Crispus and non-overwintered-stressed Chondrus crispus dietary supplementations. Asian J Med Sci. 2018; 9(6): 7-13.
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.
Adverse-effects data: Natural Medicines, Therapeutic Research Center
Dosing
There is no established, standardized dose for sea moss. Iodine content varies widely between products, which makes consistent dosing difficult and increases the risk of getting too much.
If you choose to use it, follow the directions on the product label and start low. Because of the iodine concern, it is wise to keep amounts modest and to check with your pharmacist or doctor first, especially if you have a thyroid condition, are pregnant or breastfeeding, or take other supplements that contain iodine.
Pregnancy & Breastfeeding
Sea Moss & Pregnancy
Sea Moss & Breastfeeding
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
© 2026 Therapeutic Research Center
Pregnancy & lactation ratings: Natural Medicines, Therapeutic Research Center
References & further reading
The 3 references that drive our Sea Moss 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.
- Darias-Rosales J, Rubio C, Gutiérrez ÁJ, Paz S, Hardisson A. Risk assessment of iodine intake from the consumption of red seaweeds (Palmaria palmata and Chondrus crispus). Environ Sci Pollut Res Int 2020;27(36):45737-45741. PubMed
- U.S. Department of Agriculture (USDA). Agricultural Research Service. FoodData Central. Seaweed, irishmoss, raw. April 2019. Available at: https://fdc.nal.usda.gov/fdc-app.html#/food-details/168456/nutrients. Accessed Aug. 30, 2022.
- Palmieri B, Vadalà M, Laurino C. Clinical effects of overwintered-stressed Chondrus Crispus and non-overwintered-stressed Chondrus crispus dietary supplementations. Asian J Med Sci. 2018; 9(6): 7-13. DOI
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.
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
Pharmacist Counseling Corner
Sea Moss: Common Questions
What is Sea Moss used for, and does it work?
People use Sea Moss for a range of reasons, but according to the Natural Medicines database the current clinical evidence is insufficient to confirm it works for the specific conditions it has been studied for. See the graded list on this page, and talk to your pharmacist or doctor before relying on it for any condition.
Does Sea Moss interact with prescription medications?
Yes. We list 22 medications with a known interaction with Sea Moss. Use the checker above to see how Sea Moss interacts with a specific drug.
How are Sea Moss interactions rated?
Each interaction is graded major, moderate, or minor based on how clinically significant it is and the strength of the evidence behind it. Major interactions are the most serious and are best avoided, or used only under close professional supervision.
Is it safe to take Sea Moss with my medications?
It depends on the specific medication. Some combinations are fine, while others call for monitoring, timing changes, or should be avoided. Check your exact drug above and confirm with your pharmacist or doctor before starting, stopping, or changing anything.
Where does this Sea Moss interaction information come from?
Our interaction data is built on the Natural Medicines database — an evidence-graded reference for vitamins, herbs, and supplements — and is reviewed by licensed HelloPharmacist pharmacists, who may add clinical context.
What is Sea Moss used for?
People commonly use it as a source of iodine and minerals and for thyroid, immune, digestive, skin, and hair support. Strong human evidence for most of these uses is lacking.
Is Sea Moss safe to take every day?
Daily use is questionable mainly because of its high and variable iodine content, which can affect the thyroid. Talk to your pharmacist or doctor before taking it regularly, especially if you have a thyroid problem.
Can I take Sea Moss while pregnant or breastfeeding?
It is best to avoid Sea Moss supplements during pregnancy and breastfeeding because the iodine and possible heavy-metal content are unpredictable and could harm the baby.
Does Sea Moss really boost the immune system or improve skin?
These claims come mostly from tradition, marketing, and lab studies, not from solid human research. There is not enough reliable evidence to confirm these benefits.
Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy
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