Other Name(s):

Algas, Algue Rouge Marine, Carrageen, Carrageenin, Carragenano, Carragenina, Carragheenan, Carraghénane, Carraghénine, Chondrus crispus, Chondrus Extract, Euchema species, Extrait de Mousse d'Irlande, Galgarine, Gigartina chamissoi, Gigartina mamillosa, Gigartina skottsbergii, Irish Moss Algae, Irish Moss Extract, Mousse d'Irlande, Red Marine Algae.


Carrageenan is made from parts of various red algae or seaweeds and is used for medicine.

Carrageenan is used for coughs, bronchitis, tuberculosis, and intestinal problems. The French use a form that has been changed by adding acid and high temperatures. This form is used to treat peptic ulcers, and as a bulk laxative.

Some people apply carrageenan directly to the skin for discomfort around the anus.

In manufacturing, carrageenan is used as a binder, thickening agent, and as a stabilizer in medications, foods, and toothpaste. Carrageenan is also an ingredient in weight loss products.

How does it work?

Carrageenan contains chemicals that may decrease stomach and intestinal secretions. Large amounts of carrageenan seem to pull water into the intestine, and this may explain why it is tried as a laxative. Carrageenan also might decrease pain and swelling (inflammation).

Uses & Effectiveness

Insufficient Evidence to Rate Effectiveness for...

More evidence is needed to rate the effectiveness of carrageenan for these uses.

Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, and Insufficient Evidence to Rate (detailed description of each of the ratings).


Vitamin D Deficiency: How Much Vitamin D Is Enough? See Slideshow

Side Effects

Carrageenan is LIKELY SAFE for most people when taken by mouth in food amounts. There is a chemically altered form of carrageenan that is available in France to treat peptic ulcers. This form is POSSIBLY UNSAFE because there's some evidence that it might cause cancer.

Special Precautions & Warnings

Pregnancy and breast-feeding: Carrageenan is LIKELY SAFE in amounts found in food, but there's not enough information to know if it's safe in the larger amounts that are used as medicine. It's best to stay on the safe side and avoid use in medicinal amounts.

Bleeding disorders: Carrageenan might slow blood clotting and increase bleeding. In theory, carrageenan might make bleeding disorders worse.

Low blood pressure: Carrageenan might lower blood pressure. In theory, taking carrageenan might make blood pressure become too low in people with low blood pressure.

Surgery: Carrageenan might slow blood clotting and lower blood pressure in some people. In theory, carrageenan might increase the risk for bleeding and interfere with blood pressure control during surgical procedures. Stop using carrageenan at least 2 weeks before a scheduled surgery.


Medications for high blood pressure (Antihypertensive drugs)Interaction Rating: Moderate Be cautious with this combination.Talk with your health provider.

Carrageenan might decrease blood pressure. Taking carrageenan along with medications for high blood pressure might cause your blood pressure to go too low.

Some medications for high blood pressure include captopril (Capoten), enalapril (Vasotec), losartan (Cozaar), valsartan (Diovan), diltiazem (Cardizem), Amlodipine (Norvasc), hydrochlorothiazide (HydroDiuril), furosemide (Lasix), and many others.

Medications taken by mouth (Oral drugs)Interaction Rating: Moderate Be cautious with this combination.Talk with your health provider.

Carrageenan is a thick gel. Carrageenan might stick to medications in the stomach and intestines. Taking carrageenan at the same time as medications that you take by mouth might decrease how much medication your body absorbs, and decrease the effectiveness of your medication. To prevent this interaction, take carrageenan at least one hour after medications you take by mouth.

Medications that slow blood clotting (Anticoagulant / Antiplatelet drugs)Interaction Rating: Moderate Be cautious with this combination.Talk with your health provider.

Carrageenan might slow blood clotting. Taking carrageenan along with medications that also slow clotting might increase the chances of bruising and bleeding.

Some medications that slow blood clotting include aspirin, clopidogrel (Plavix), diclofenac (Voltaren, Cataflam, others), ibuprofen (Advil, Motrin, others), naproxen (Anaprox, Naprosyn, others), dalteparin (Fragmin), enoxaparin (Lovenox), heparin, warfarin (Coumadin), and others.


Next to red peppers, you can get the most vitamin C from ________________. See Answer


The appropriate dose of carrageenan depends on several factors such as the user's age, health, and several other conditions. At this time there is not enough scientific information to determine an appropriate range of doses for carrageenan. Keep in mind that natural products are not always necessarily safe and dosages can be important. Be sure to follow relevant directions on product labels and consult your pharmacist or physician or other healthcare professional before using.

Health Solutions From Our Sponsors

Reviewed on 6/14/2021

Benitz, K. F., Golberg, L., and Coulston, F. Intestinal effects of carrageenans in the rhesus monkey (Macaca mulatta). Food Cosmet.Toxicol. 1973;11(4):565-575. View abstract.

Bianchi, M. and Broggini, M. Anti-hyperalgesic effects of nimesulide: studies in rats and humans. Int J Clin.Pract.Suppl 2002;(128):11-19. View abstract.

Borthakur, A., Bhattacharyya, S., Dudeja, P. K., and Tobacman, J. K. 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. View abstract.

Buck, C. B., Thompson, C. D., Roberts, J. N., Muller, M., Lowy, D. R., and Schiller, J. T. Carrageenan is a potent inhibitor of papillomavirus infection. PLoS.Pathog. 2006;2(7):e69. View abstract.

Carlucci, M. J., Scolaro, L. A., and Damonte, E. B. Inhibitory action of natural carrageenans on Herpes simplex virus infection of mouse astrocytes. Chemotherapy 1999;45(6):429-436. View abstract.

Carlucci, M. J., Scolaro, L. A., Noseda, M. D., Cerezo, A. S., and Damonte, E. B. Protective effect of a natural carrageenan on genital herpes simplex virus infection in mice. Antiviral Res. 2004;64(2):137-141. View abstract.

Chen, H., Yan, X., Lin, J., Wang, F., and Xu, W. Depolymerized products of lambda-carrageenan as a potent angiogenesis inhibitor. J Agric.Food Chem. 8-22-2007;55(17):6910-6917. View abstract.

Coggins, C., Blanchard, K., Alvarez, F., Brache, V., Weisberg, E., Kilmarx, P. H., Lacarra, M., Massai, R., Mishell, D., Jr., Salvatierra, A., Witwatwongwana, P., Elias, C., and Ellertson, C. Preliminary safety and acceptability of a carrageenan gel for possible use as a vaginal microbicide. Sex Transm.Infect. 2000;76(6):480-483. View abstract.

Cummins, J. E., Jr., Guarner, J., Flowers, L., Guenthner, P. C., Bartlett, J., Morken, T., Grohskopf, L. A., Paxton, L., and Dezzutti, C. S. 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. View abstract.

DiNinno, V. and McCandless, E. L. The chemistry and immunochemistry of carrageenans from Eucheuma and related algal species. Carbohydr.Res. 1978;66:85-93. View abstract.

Dumelod, B. D., Ramirez, R. P., Tiangson, C. L., Barrios, E. B., and Panlasigui, L. N. Carbohydrate availability of arroz caldo with lambda-carrageenan. Int.J.Food Sci.Nutr. 1999;50(4):283-289. View abstract.

Elias, C. J., Coggins, C., Alvarez, F., Brache, V., Fraser, I. S., Lacarra, M., Lahteenmaki, P., Massai, R., Mishell, D. R., Jr., Phillips, D. M., and Salvatierra, A. M. Colposcopic evaluation of a vaginal gel formulation of iota-carrageenan. Contraception 1997;56(6):387-389. View abstract.

Flower, R. J., Harvey, E. A., and Kingston, W. P. Inflammatory effects of prostaglandin D2 in rat and human skin. Br.J Pharmacol. 1976;56(2):229-233. View abstract.

Jol, C. N., Neiss, T. G., Penninkhof, B., Rudolph, B., and De Ruiter, G. A. A novel high-performance anion-exchange chromatographic method for the analysis of carrageenans and agars containing 3,6-anhydrogalactose. Anal.Biochem 3-15-1999;268(2):213-222. View abstract.

Kilmarx, P. H., van de Wijgert, J. H., Chaikummao, S., Jones, H. E., Limpakarnjanarat, K., Friedland, B. A., Karon, J. M., Manopaiboon, C., Srivirojana, N., Yanpaisarn, S., Supawitkul, S., Young, N. L., Mock, P. A., Blanchard, K., and Mastro, T. D. 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. View abstract.

Maguire, R. A., Bergman, N., and Phillips, D. M. Comparison of microbicides for efficacy in protecting mice against vaginal challenge with herpes simplex virus type 2, cytotoxicity, antibacterial properties, and sperm immobilization. Sex Transm.Dis. 2001;28(5):259-265. View abstract.

Ogino, M., Majima, M., Kawamura, M., Hatanaka, K., Saito, M., Harada, Y., and Katori, M. 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. View abstract.

Panlasigui, L. N., Baello, O. Q., Dimatangal, J. M., and Dumelod, B. D. Blood cholesterol and lipid-lowering effects of carrageenan on human volunteers. Asia Pac.J.Clin.Nutr. 2003;12(2):209-214. View abstract.

Perotti, M. E., Pirovano, A., and Phillips, D. M. Carrageenan formulation prevents macrophage trafficking from vagina: implications for microbicide development. Biol.Reprod. 2003;69(3):933-939. View abstract.

Pujol, C. A., Scolaro, L. A., Ciancia, M., Matulewicz, M. C., Cerezo, A. S., and Damonte, E. B. Antiviral activity of a carrageenan from Gigartina skottsbergii against intraperitoneal murine herpes simplex virus infection. Planta Med 2006;72(2):121-125. View abstract.

Raouf, A. H., Hildrey, V., Daniel, J., Walker, R. J., Krasner, N., Elias, E., and Rhodes, J. M. 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. View abstract.

Schaeffer, D. J. and Krylov, V. S. Anti-HIV activity of extracts and compounds from algae and cyanobacteria. Ecotoxicol.Environ.Saf 2000;45(3):208-227. View abstract.

Tobacman, J. K. and Walters, K. S. Carrageenan-induced inclusions in mammary myoepithelial cells. Cancer Detect.Prev. 2001;25(6):520-526. View abstract.

Tobacman, J. K. Review of harmful gastrointestinal effects of carrageenan in animal experiments. Environ.Health Perspect. 2001;109(10):983-994. View abstract.

Tobacman, J. K., Wallace, R. B., and Zimmerman, M. B. Consumption of carrageenan and other water-soluble polymers used as food additives and incidence of mammary carcinoma. Med.Hypotheses 2001;56(5):589-598. View abstract.

Watanabe, K., Reddy, B. S., Wong, C. Q., and Weisburger, J. H. Effect of dietary undegraded carrageenan on colon carcinogenesis in F344 rats treated with azoxymethane or methylnitrosourea. Cancer Res. 1978;38(12):4427-4430. View abstract.

Whitehead, S. J., Kilmarx, P. H., Blanchard, K., Manopaiboon, C., Chaikummao, S., Friedland, B., Achalapong, J., Wankrairoj, M., Mock, P., Thanprasertsuk, S., and Tappero, J. W. Acceptability of Carraguard vaginal gel use among Thai couples. AIDS 11-14-2006;20(17):2141-2148. View abstract.

Yuan, H., Song, J., Zhang, W., Li, X., Li, N., and Gao, X. Antioxidant activity and cytoprotective effect of kappa-carrageenan oligosaccharides and their different derivatives. Bioorg.Med Chem.Lett. 3-1-2006;16(5):1329-1334. View abstract.

Zacharopoulos, V. R. and Phillips, D. M. Vaginal formulations of carrageenan protect mice from herpes simplex virus infection. Clin.Diagn.Lab Immunol. 1997;4(4):465-468. View abstract.

Dr. Duke's Phytochemical and Ethnobotanical Databases. Available at:

Electronic Code of Federal Regulations. Title 21. Part 182 -- Substances Generally Recognized As Safe. Available at:

Fetrow CW, Avila JR. Professional's Handbook of Complementary & Alternative Medicines. 1st ed. Springhouse, PA: Springhouse Corp., 1999.

Health Solutions From Our Sponsors