- Irish moss
- Algae, algal polysaccharides, anhydrogalactose, bejin behan (Breton), bejin gwenn (Breton), Betaphycus gelatinum, blomkalstang (Danish), botelho crespo (Portuguese), bouch (Breton), bouch farad youd (Breton), bouch gad (Breton), bouch gwenn (Breton), bouchounoù (Breton), cairgin (Gaelic), Callophyllis hombroniana, caragaen, caragahen, carragaheen, carrageen, carrageen moss, carrageenin, carrageentang (Danish), carragheen, carraghèen (French), carragheenan, Carraguard®, carraigín (Irish), carrapucho (Galician), Chondrus crispus, chondrus extract, Chondrus mamillosus, clúimhín cait (Irish), clúimhín caitcarraigín (Irish), cottonii, creba (Galician), curly gristle moss, curly moss, Dorset weed, Dragendorff, driesflik (Norwegian), Eucheuma cottonii, Eucheuma denticulatum, Eucheuma gelatinae, Eucheuma spp., Eucheuma spinosum, fiadháin (Irish), fjörugrös (Icelandic), folha de alface (Portuguese), folhina (Portuguese), fuco carageo, fuco crispo (Italian), Fucus crispus Linné, galactopyranose, galactose 4-sulphate, gelatintang (Norwegian), Gigartina acicularis, Gigartina canaliculata, Gigartina mamillosa, Gigartina pistillata, Gigartina skottsbergii, Gigartina stellata, Gigartinaceae (family), Gigartinales, goémon blanc (French), goémon fries (French), goémon rouge (French), hirakotoji (Japanese), Hypnea musciformis, Iers mos (Dutch), iota carrageenan, Iridaea ciliata, Iridaea ciliate, Iridaea laminaroides, Irish moss extract, Irländischer Perltang (German), Irländisches Moos (German), Irlandsk mos (Danish), jargod (Breton), jelly moss, Kallymeniaceae, kappa carrageenan, Kappaphycus alvarezii, Kappaphycus cottonii, Kappaphycus striatum, karragaheen (German), karrageentari (Faroese), karragen (Turkish), karragenalg (karragentang) (Swedish), Killeen, knorpeltang (German), krusflik (Norwegian), lambda carrageenan, lambda-carrageenan, Lamouroux, lichen, liken ruz (Breton), liquen (Spanish), marine algae, Mastocarpus mamillosus Kützing, Mastocarpus stellatus, mathair an diulisg (Gaelic), Mazzaella laminaroides, mousse d’irlande, mousse marine perlée (French), mousse perlée (French), mu carrageenan, muschio irlandese (Italian), musco d’lrlanda (Italian), musgo de Irlanda (Spanish), musgo gordo (Portuguese), musgo marino (Spanish), musgo marino perlado (Spanish), musgo perlado (Spanish), mwsog Iwerddon (Welsh), nu carrageenan, ouca riza (Galician), ougnachou-ru (Breton), pata de galiña (Galician), PC 213, PC-503, pearl moss, perimoos, perlmoos (German), petit goémon (French), Phacelocarpus peperocarpos, pigwiacis, pioka (Breton), poligeenan, red algae, red seaweed, Rhodophyceae, Rhodophyta, Rhodophytaa, Sarcothalia crispate, Sarcothalia crispate, sea moss, seamuisin, seaweed, seaweed extract, Sphaerococcus crispus Agardh, Sphaerococcus mamillosus Agardh, spinosum, stackhouse, teil piko (Breton), teles (Breton), theta carrageenan, tilez (Breton), tochaka (Japanese), tsunomata (Japanese), upsilon carrageenan, vaginal gel, white wrack.
- Carrageenans are carbohydrates extracted from red seaweeds (such as Irish moss) and other sources. Irish moss grows around Ireland, as well as other coasts in Europe, and the Atlantic coasts of the United States. The Irish moss popularly used as a ground cover (Sagina subulata) is not the same as the Irish moss discussed in this monograph (Chondrus crispus).
- Traditionally, carrageenan has been taken by mouth to soothe mucous membranes and as a laxative. Extracts of carrageenan have been used as food additives for hundreds of years. Carrageenan is currently used as a thickener and stabilizer for a wide range of foods, and is also used in personal hygiene products and drugs.
- Carrageenan may lower lipid (cholesterol and triglyceride) and blood sugar levels. Although not well studied in humans, carrageenan-based gels may help prevent HIV transmission.
These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.
Although not well studied in humans, carrageenan-based gels may prevent HIV transmission during sexual intercourse. Overall, studies suggest that carrageenan may be safe for use by males and females. High quality clinical study is needed to confirm these early results.
In clinical study, a diet containing carrageenan-enriched foods lowered cholesterol and triglyceride levels. Further clinical trials are required before carrageenan can be recommended for its lipid-lowering effects.
*Key to grades:
The below uses are based on tradition, scientific theories, or limited research. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider. There may be other proposed uses that are not listed below.
Adults (18 years and older)
- Traditionally, carrageenan is taken by mouth as a tea after it is boiled and flavored.
- For lipid lowering, carrageenan-enriched foods have been taken for eight weeks.
- For HIV prevention, 5 milliliters of carrageenan gel has been applied inside the vagina for seven days; one application a minimum of three times per week has also been used.
Children (under 18 years old)
- There is no proven safe or effective dose for carrageenan in children.
The below doses are based on scientific research, publications, traditional use, or expert opinion. Many herbs and supplements have not been thoroughly tested, and safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients, even within the same brand. The below doses may not apply to all products. You should read product labels, and discuss doses with a qualified healthcare provider before starting therapy.
- Avoid with known allergy or hypersensitivity to seaweed, algae, or carrageenan.
Side Effects and Warnings
- Carrageenan is generally safe and well-tolerated when used by mouth at levels found in foods. Carrageenan is possibly unsafe when taken by mouth in degraded, poligeenan form, or when taken by infants. The fiber in carrageenan may impair the absorption of drugs, herbs, or supplements taken by mouth.
- Carrageenan may increase the risk of bleeding. Caution is advised in patients with bleeding disorders or taking drugs, herbs, or supplements that may increase the risk of bleeding. Dosing adjustments may be necessary.
- Carrageenan may lower blood sugar levels. Caution is advised in patients with diabetes or hypoglycemia, and in those taking drugs, herbs, or supplements that affect blood sugar. Blood glucose levels may need to be monitored by a qualified healthcare professional, including a pharmacist, and medication adjustments may be necessary.
- Carrageenan may cause low blood pressure. Caution is advised in patients with blood pressure disorders or in those taking drugs, herbs, or supplements that lower blood pressure.
- Carrageenan may have negative effects on the immune system which may result in increased inflammation or infection. Caution is advised in patients with immune or inflammatory disorders or in those using drugs, herbs, or supplements for these disorders.
- Carrageenan may cause cramping, diarrhea, and possibly an increased risk of stomach cancer or stomach ulcers. Caution is advised in patients with stomach or intestinal disorders or with, or at risk for, cancer.
- Carrageenan gel applied to the vagina may cause bladder fullness, difficulty urinating, genital warmth, lower abdominal pain, vaginal itching and burning, and abnormal vaginal discharge.
Pregnancy and Breastfeeding
- Carrageenan is not recommended for pregnant or breastfeeding women due to lack of sufficient data. Carrageenan may be unsafe in infants.
The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.
Interactions with Drugs
- Carrageenan may impair absorption of drugs taken by mouth.
- Carrageenan may lower blood sugar levels. Caution is advised when using medications that may also lower blood sugar. Patients taking drugs for diabetes by mouth or insulin should be monitored closely by a qualified healthcare professional, including a pharmacist. Medication adjustments may be necessary.
- Carrageenan may increase the risk of bleeding when taken with drugs that increase the risk of bleeding. Some examples include aspirin, anticoagulants (“blood thinners”) such as warfarin (Coumadin®) or heparin, anti-platelet drugs such as clopidogrel (Plavix®), and non-steroidal anti-inflammatory drugs such as ibuprofen (Motrin®, Advil®) or naproxen (Naprosyn®, Aleve®).
- Carrageenan may cause low blood pressure. Caution is advised in patients taking drugs that lower blood pressure.
- Carrageenan may increase inflammation or affect the immune system. Caution is advised in patients taking drugs that stimulate or suppress the immune system.
- Carrageenan applied vaginally may increase side effects of other vaginal drugs.
- Carrageenan may add to the effects of cholesterol lowering agents, anti-cancer agents, HIV drugs, antiviral drugs, eye medications, azoxymethane, nitrosomethylurea, and azidodeoxythymidine (AZT).
Interactions with Herbs and Dietary Supplements
- Carrageenan may impair absorption of herbs or supplements taken by mouth.
- Carrageenan may lower blood sugar levels. Caution is advised when using herbs or supplements that may also lower blood sugar. Blood glucose levels may require monitoring, and doses may need adjustment.
- Carrageenan may increase the risk of bleeding when taken with herbs and supplements that are believed to increase the risk of bleeding. Multiple cases of bleeding have been reported with the use of Ginkgo biloba, and fewer cases with garlic and saw palmetto. Numerous other agents may theoretically increase the risk of bleeding, although this has not been proven in most cases.
- Carrageenan may cause low blood pressure. Caution is advised in patients taking herbs or supplements that lower blood pressure.
- Carrageenan may increase inflammation or affect the immune system. Caution is advised in patients taking herbs or supplements that stimulate or suppress the immune system.
- Carrageenan applied vaginally may increase side effects of other vaginal herbs or supplements.
- Carrageenan may add to the effects of antiviral herbs or supplements, antioxidants, herbs or supplements used to lower cholesterol, or herbs or supplements used for cancer, HIV, or for the eye.
Most herbs and supplements have not been thoroughly tested for interactions with other herbs, supplements, drugs, or foods. The interactions listed below are based on reports in scientific publications, laboratory experiments, or traditional use. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy.
- This information is based on a systematic review of scientific literature edited and peer-reviewed by contributors to the Natural Standard Research Collaboration ().
- Bonferoni, MC, Chetoni, P, Giunchedi, P, et al. Carrageenan-gelatin mucoadhesive systems for ion-exchange based ophthalmic delivery: in vitro and preliminary in vivo studies. Eur J Pharm Biopharm. 2004;57(3):465-472.
- Borthakur, A, Bhattacharyya, S, Dudeja, PK, et al. Carrageenan induces interleukin-8 production through distinct Bcl10 pathway in normal human colonic epithelial cells. Am J Physiol Gastrointest.Liver Physiol 2007;292(3):G829-G838.
- Buck, CB, Thompson, CD, Roberts, JN, et al. Carrageenan is a potent inhibitor of papillomavirus infection. PLoS Pathog. 2006;2(7):e69.
- Carlucci, MJ, Scolaro, LA, and Damonte, EB. Herpes simplex virus type 1 variants arising after selection with an antiviral carrageenan: lack of correlation between drug susceptibility and syn phenotype. J Med Virol. 2002;68(1):92-98.
- Coggins, C, Blanchard, K, Alvarez, F, et al. Preliminary safety and acceptability of a carrageenan gel for possible use as a vaginal microbicide. Sex Transm Infect. 2000;76(6):480-483.
- Cummins, JE, Jr, Guarner, J, Flowers, L, et al. Preclinical testing of candidate topical microbicides for anti-human immunodeficiency virus type 1 activity and tissue toxicity in a human cervical explant culture. Antimicrob Agents Chemother. 2007;51(5):1770-1779.
- Elias, CJ, Coggins, C, Alvarez, F, et al. Colposcopic evaluation of a vaginal gel formulation of iota-carrageenan. Contraception 1997;56(6):387-389.
- Kilmarx, PH, van de Wijgert, JH, Chaikummao, S, et al. Safety and acceptability of the candidate microbicide Carraguard in Thai Women: findings from a Phase II Clinical Trial. J Acquir Immune Defic Syndr. 11-1-2006;43(3):327-334.
- Ogino, M, Majima, M, Kawamura, M, et al. Increased migration of neutrophils to granulocyte-colony stimulating factor in rat carrageenin-induced pleurisy: roles of complement, bradykinin, and inducible cyclooxygenase-2. Inflamm Res. 1996;45(7):335-346.
- Panlasigui, LN, Baello, OQ, Dimatangal, JM, et al. Blood cholesterol and lipid-lowering effects of carrageenan on human volunteers. Asia Pac.J.Clin.Nutr. 2003;12(2):209-214.
- Perotti, ME, Pirovano, A, and Phillips, DM. Carrageenan formulation prevents macrophage trafficking from vagina: implications for microbicide development. Biol Reprod. 2003;69(3):933-939.
- Raouf, AH, Hildrey, V, Daniel, J, et al. Enteral feeding as sole treatment for Crohn’s disease: controlled trial of whole protein v amino acid based feed and a case study of dietary challenge. Gut 1991;32(6):702-707.
- Schaeffer, DJ and Krylov, VS. Anti-HIV activity of extracts and compounds from algae and cyanobacteria. Ecotoxicol Environ Saf 2000;45(3):208-227.
- Tobacman, JK, Wallace, RB, and Zimmerman, MB. Consumption of carrageenan and other water-soluble polymers used as food additives and incidence of mammary carcinoma. Med Hypotheses 2001;56(5):589-598.
- Vlieghe, P, Clerc, T, Pannecouque, C, et al. Synthesis of new covalently bound kappa-carrageenan-AZT conjugates with improved anti-HIV activities. J.Med.Chem. 3-14-2002;45(6):1275-1283.
Natural Standard developed the above evidence-based information based on a thorough systematic review of the available scientific articles. For comprehensive information about alternative and complementary therapies on the professional level, go to . Selected references are listed below.