What is it?
Bladderwrack is a type of seaweed. People use the whole plant to make medicine.
Bladderwrack is used for many conditions, but, so far, there isn’t enough scientific evidence to determine whether or not it is effective for any of them. It’s also important to note that it’s not safe to take bladderwrack by mouth.
Bladderwrack is used for thyroid disorders including underactive thyroid (myxedema), over-sized thyroid gland (goiter), and iodine deficiency. It is also used for obesity, arthritis, joint pain, “hardening of the arteries” (arteriosclerosis), digestive disorders, heartburn, “blood cleansing,” constipation, bronchitis, emphysema, urinary tract disorders, and anxiety. Other uses include boosting the immune system and increasing energy.
Some people also apply bladderwrack to the skin for skin diseases, burns, aging skin, and insect bites.
Don’t confuse bladderwrack with bladderwort.
How effective is it?
Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, Ineffective, and Insufficient Evidence to Rate.
The effectiveness ratings for BLADDERWRACK are as follows:
Insufficient evidence to rate effectiveness for...
- Obesity. Early research suggests that bladderwrack, used along with lecithin and vitamins, doesn’t help people lose weight and keep it off.
- Thyroid problems, including an over-sized thyroid gland (goiter).
- Iodine deficiency.
- Achy joints (rheumatism).
- “Hardening of the arteries” (arteriosclerosis).
- Digestive problems.
- “Blood cleansing”.
- Other conditions.
More evidence is needed to rate bladderwrack for these uses.
Bladderwrack, like many sea plants, contains varying amounts of iodine, which is used to prevent or treat some thyroid disorders. Bladderwrack products may contain varying amounts of iodine, which makes it an inconsistent source of iodine. Bladderwrack also contains algin, which can act as a laxative to help the stool pass through the bowels.
Bladderwrack is POSSIBLY UNSAFE. It may contain high concentrations of iodine, which could cause or worsen some thyroid problems. Prolonged, high intake of dietary iodine is linked with goiter and increased risk of thyroid cancer. Treatment of thyroid problems should not be attempted without medical supervision.
Like other sea plants, bladderwrack can concentrate toxic heavy metals, such as arsenic, from the water in which it lives.
Special precautions & warnings:
Pregnancy and breast-feeding: Bladderwrack is LIKELY UNSAFE during pregnancy and breast-feeding. Don’t use it.
Thyroid problems known as hyperthyroidism (too much thyroid hormone), or hypothyroidism (too little thyroid hormone): Bladderwrack contains significant amounts of iodine, which might make hyperthyroidism and hypothyroidism worse. Don’t use it.
Infertility: Preliminary research suggests that taking bladderwrack might make it harder for women to get pregnant.
Iodine allergy: Bladderwrack contains significant amounts of iodine, which could cause an allergic reaction in sensitive people. Don’t use it.
Surgery: Bladderwrack might slow blood clotting. There is a concern that it might cause extra bleeding during and after surgery. Stop taking bladderwrack at least 2 weeks before surgery.
Be cautious with this combination.
Medications for an overactive thyroid (Antithyroid drugs)
Bladderwrack can contain significant amounts of iodine. Iodine can affect the thyroid. Taking iodine along with medications for an overactive thyroid might decrease the thyroid too much. Do not take bladderwrack if you are taking medications for an overactive thyroid.
Some of these medications include methenamine mandelate (Methimazole), methimazole (Tapazole), potassium iodide (Thyro-Block), and others.
Medications that slow blood clotting (Anticoagulant / Antiplatelet drugs)
Bladderwrack might slow blood clotting. Taking bladderwrack 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.
Herbs and supplements that might slow blood clotting
Bladderwrack might slow blood clotting. Taking bladderwrack along with herbs that also slow clotting might increase the chances of bruising and bleeding. These herbs include angelica, clove, danshen, fenugreek, feverfew, garlic, ginger, ginkgo, Panax ginseng, poplar, red clover, turmeric, and others.
There are no known interactions with foods.
The appropriate dose of bladderwrack 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 bladderwrack. 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.
Alga Noruega o Nudosa, Algue Laminaire, Ascophylle Noueuse, Ascophyllum nodosum, Atlantic Kelp, Black Tang, Bladder Fucus, Bladder Wrack, Blasentang, Chêne Marin, Cutweed, Fucus, Fucus Vésiculeux, Fucus vesiculosis, Goémon, Kelp, Kelpware, Kelp-Ware, Knotted Wrack, Laitue de Mer, Laitue Marine, Laminaire, Marine Oak, Meereiche, Norwegian Seaweed, Quercus Marina, Rockweed, Rockwrack, Schweintang, Sea Kelp, Seawrack, Tang, Varech, Varech Vésiculeux.
To learn more about how this article was written, please see the Natural Medicines Comprehensive Database methodology.methodology (http://www.nlm.nih.gov/medlineplus/druginfo/natural/methodology.html).
To see all references for the Bladderwrack page, please go to http://www.nlm.nih.gov/medlineplus/druginfo/natural/726.html.
- US Department of Health and Human Services, Public Health Service. Agency for Toxic Substances and Disease Registry. Toxicological profile for strontium. April 2004. Available at: www.atsdr.cdc.gov/toxprofiles/tp159.pdf. (Accessed 8 August 2006).
- Agarwal SC, Crook JR, Pepper CB. Herbal remedies -- how safe are they? A case report of polymorphic ventricular tachycardia/ventricular fibrillation induced by herbal medication used for obesity. Int J Cardiol 2006;106:260-1.
- Okamura K, Inoue K, Omae T. A case of Hashimoto's thyroiditis with thyroid immunological abnormality manifested after habitual ingestion of seaweed. Acta Endocrinol (Copenh) 1978;88:703-12.
- Bjorvell H, Rössner S. Long-term effects of commonly available weight reducing programmes in Sweden. Int J Obes 1987;11:67-71.
- Conz PA, La Greca G, Benedetti P, et al. Fucus vesiculosus: a nephrotoxic alga? Nephrol Dial Transplant 1998;13:526-7.
- Fujimura T, Tsukahara K, Moriwaki S, et al. Treatment of human skin with an extract of Fucus vesiculosus changes its thickness and mechanical properties. J Cosmet Sci 2002;53:1-9.
- Koyanagi S, Tanigawa N, Nakagawa H, et al. Oversulfation of fucoidan enhances its anti-angiogenic and antitumor activities. Biochem Pharmacol 2003;65:173-9.
- Durig J, Bruhn T, Zurborn KH, et al. Anticoagulant fucoidan fractions from Fucus vesiculosus induce platelet activation in vitro. Thromb Res 1997;85:479-91.
- O'Leary R, Rerek M, Wood EJ. Fucoidan modulates the effect of transforming growth factor (TGF)-beta1 on fibroblast proliferation and wound repopulation in in vitro models of dermal wound repair. Biol Pharm Bull 2004;27:266-70.
- Patankar MS, Oehninger S, Barnett T, et al. A revised structure for fucoidan may explain some of its biological activities. J Biol Chem 1993;268:21770-6.
Baba M, Snoeck R, Pauwels R, de Clercq E. Sulfated polysaccharides are potent and selective inhibitors of various enveloped viruses, including herpes simplex virus, cytomegalovirus, vesicular stomatitis virus, and human immunodeficiency virus. Antimicrob Agents Chemother 1988;32:1742-5.
- Ruperez P, Ahrazem O, Leal JA. Potential antioxidant capacity of sulfated polysaccharides from the edible marine brown seaweed Fucus vesiculosus. J Agric Food Chem 2002;50:840-5.
- Beress A, Wassermann O, Tahhan S, et al. A new procedure for the isolation of anti-HIV compounds (polysaccharides and polyphenols) from the marine alga Fucus vesiculosus. J Nat Prod 1993;56:478-88.
- Criado MT, Ferreiros CM. Toxicity of an algal mucopolysaccharide for Escherichia coli and Neisseria meningitidis strains. Rev Esp Fisiol 1984;40:227-30.
- Skibola CF. The effect of Fucus vesiculosus, an edible brown seaweed, upon menstrual cycle length and hormonal status in three pre-menopausal women: a case report. BMC Complement Altern Med 2004;4:10.
- Phaneuf D, Cote I, Dumas P, et al. Evaluation of the contamination of marine algae (Seaweed) from the St. Lawrence River and likely to be consumed by humans. Environ Res 1999;80:S175-S182.
- Baker DH. Iodine toxicity and its amelioration. Exp Biol Med (Maywood) 2004;229:473-8.
- Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington, DC: National Academy Press, 2002. Available at: www.nap.edu/books/0309072794/html/.
- Pye KG, Kelsey SM, House IM, et al. Severe dyserythropoeisis and autoimmune thrombocytopenia associated with ingestion of kelp supplement. Lancet 1992;339:1540.
- Show more references
- Show fewer references
Last reviewed - 12/13/2011
This copyrighted, evidence-based medicine resource is provided by Natural Medicines Comprehensive Database Consumer Version. Natural Medicines Comprehensive Database disclaims any responsibility related to consequences of using any product. This monograph should not replace advice from a healthcare professional and should not be used for the diagnosis or treatment of any medical condition.
Copyright © 1995 - 2013 Therapeutic Research Faculty
, publishers of Natural Medicines Comprehensive Database
, Prescriber’s Letter
, Pharmacist’s Letter
. All rights reserved. For scientific data on natural medicines, professionals may consult the Professional Version of Natural Medicines Comprehensive DatabaseNatural Medicines Comprehensive Database (http://www.naturaldatabase.com/)