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SupplementScience

Sea Moss Side Effects & Safety

Reviewed by·PharmD, BCPS

This content is for informational purposes only and does not constitute medical advice. Consult your healthcare provider before starting any supplement. Full disclaimer

Safety Profile

Overall safety rating: Safe with Caution

Potential Side Effects

  • Excessive iodine intake — sea moss iodine content is highly variable; overconsumption can cause thyroid dysfunction including hyperthyroidism or thyroiditis
  • GI discomfort — bloating, gas, or loose stools from carrageenan content, especially at higher doses
  • Heavy metal contamination — seaweeds bioaccumulate heavy metals from their environment; source quality is critical
  • Unpleasant oceanic taste and gelatinous texture may cause nausea in sensitive individuals
  • Allergic reactions — rare but possible in individuals sensitive to seaweed or marine products

Drug & Supplement Interactions

  • Thyroid medications (levothyroxine) — high iodine content may interfere with thyroid hormone dosing and management
  • Anticoagulants (warfarin, heparin) — some seaweed polysaccharides have mild anticoagulant properties; theoretical additive effect
  • Antihypertensives — sea moss is high in potassium; may potentiate blood pressure lowering effects
  • Lithium — iodine-rich foods may affect thyroid function and alter lithium's therapeutic effects

Maximum Dose

Do not exceed: 4 tablespoons gel or 4g powder daily (higher doses risk excessive iodine intake)

Full Sea Moss Guide

References

  1. Teas J, Pino S, Critchley A, Braverman LE (2004). Variability of iodine content in common commercially available edible seaweeds. Thyroid. DOI PubMed
  2. Pereira L (2011). A review of the nutrient composition of selected edible seaweeds. Seaweed: Ecology, Nutrient Composition and Medicinal Uses (Nova Science Publishers).
  3. Liu J, Kandasamy S, Zhang J, Kirber CW, Kidber JN, Hafting JT, Critchley AT, Prithiviraj B (2015). Prebiotic effects of diet supplemented with the cultivated red seaweed Chondrus crispus or with fructo-oligo-saccharide on host immunity, colonic microbiota and gut microbial metabolites. BMC Complementary and Alternative Medicine. DOI PubMed
  4. Leibbrandt A, Meier C, König-Schuster M, Weinmüllner R, Kalthoff D, Nürnberger B, Lipber M, Mahony TJ, Grassauer A (2010). Iota-carrageenan is a potent inhibitor of influenza A virus infection. PLoS One. DOI PubMed
  5. McKim JM (2014). Food additive carrageenan: Part I: A critical review of carrageenan in vitro studies, potential pitfalls, and implications for human health and safety. Critical Reviews in Toxicology. DOI PubMed
  6. Zava TT, Zava DT (2011). Assessment of Japanese iodine intake based on seaweed consumption in Japan: a literature-based analysis. Thyroid Research. DOI PubMed