Algue Brune, Brown Algae, Brown Seaweed, Hai Dai, Kelp, Kombu, Kun Bu, Laminaire, Laminaire Digitée, Laminaire Japonaise, Laminaria digitata, Laminaria japonica, Laminariae stipites, Limu, Makombu Thallus, Sea Girdles, Sea Tangle, Seagirdle Thallus, Super Dasima, Thallus Laminariae, Tororo Kombu.


Overview Information

Laminaria is a type of seaweed. It is used as food in many Asian countries. Laminaria contains iodine, an element that the body needs to make thyroid hormones. It is also a rich source of iron and potassium. Despite serious safety concerns about laminaria, some people use laminaria as medicine.

Laminaria is used in the cervix for ending a pregnancy (abortion) or for childbirth. It is also taken by mouth for various conditions, but there is no good scientific evidence to support any of its uses.

How does it work?

Laminaria seems to be able to form a thick, sticky gel when it comes into contact with water. This allows laminaria to work as a bulk laxative. It also allows laminaria "tents" that have been placed inside the cervix to expand the cervix for procedures or to "ripen" the cervix and speed up the onset of labor. These laminaria tents absorb water, gradually swelling to a diameter of 1/2 inch over 4-6 hours. This swelling causes the cervix to expand, and that can bring on labor.


Uses & Effectiveness?

Possibly Ineffective for

  • Ending a pregnancy (abortion). The effect of laminaria on the time need to induce an abortion is conflicting. Some research shows that laminaria can shorten delivery time. Other research shows no effect. Laminaria might also increase the chance of seizures due to fever when used for abortions.
  • Childbirth. Although laminaria might speed up childbirth, it doesn't seem to reduce the number of women who need caesarean sections to deliver. Laminaria also increases the chance of infection in both mother and infant.

Insufficient Evidence for

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

Side Effects

Side Effects & Safety

When taken by mouth: Laminaria is LIKELY SAFE when it is consumed in amounts found in food. In some people it can cause acne or worsen thyroid diseases.

Laminaria is POSSIBLY UNSAFE when taken by mouth as a medicine. It contains iodine in amounts that are high enough to harm the thyroid, the gland that uses iodine to make hormones. The average laminaria-based supplement might contain as much as 1000 mcg of iodine. Taking in more than 150 mcg of iodine per day can cause a normal thyroid to become overactive or underactive, or make an overactive thyroid worse. Some laminaria products also contain significant amounts of arsenic, a chemical element that is poisonous.

When applied to the skin: There isn't enough reliable information to know if laminaria is safe to apply to the skin. Some people are allergic to laminaria.

Special Precautions & Warnings:

Pregnancy: The use of laminaria directly on the cervix during pregnancy or childbirth is POSSIBLY UNSAFE when used to ripen the cervix and LIKELY UNSAFE when used to induce labor. It can cause serious side effects for both mother and child, including infection, rupture of the cervix, and infant death. Taking laminaria by mouth as a supplement during pregnancy is UNSAFE because laminaria can affect hormones. Avoid using.

Breast-feeding: Taking laminaria by mouth as a supplement during breast-feeding is LIKELY UNSAFE because laminaria might contain some poisonous chemicals. Avoid using.

Kidney problems: Laminaria might cause dangerously high potassium and iodine levels. Don't take laminaria if you have kidney problems.

Thyroid problems: Laminaria contains significant amounts of iodine, which might make thyroid problems worse. Don't take laminaria if you have thyroid problems.



Moderate Interaction

Be cautious with this combination

  • Digoxin (Lanoxin) interacts with LAMINARIA

    Laminaria contains large amounts of potassium. Large amounts of potassium can increase the effects and side effects of digoxin (Lanoxin). Do not take laminaria if you are taking digoxin (Lanoxin).

  • Medications for high blood pressure (ACE inhibitors) interacts with LAMINARIA

    Laminaria contains large amounts of potassium. Some medications for high blood pressure can increase potassium levels in the blood. Taking laminaria along with some medications for high blood pressure might cause too much potassium in the blood.

    Some medications for high blood pressure include captopril (Capoten), enalapril (Vasotec), lisinopril (Prinivil, Zestril), ramipril (Altace), and others.

  • Potassium supplements interacts with LAMINARIA

    Laminaria contains large amounts of potassium. Taking potassium supplements along with laminaria might cause too much potassium to be in the body. Do not take laminaria if you are taking potassium supplements.

  • Thyroid hormone interacts with LAMINARIA

    The body naturally produces thyroid hormones. Laminaria might increase how much thyroid hormone the body produces. Taking laminaria along with thyroid hormone pills might increase the effects and side effects of thyroid hormones.

  • Water pills (Potassium-sparing diuretics) interacts with LAMINARIA

    Laminaria contains large amounts of potassium. Some "water pills" can also increase potassium levels in the body. Taking some "water pills" along with laminaria might cause too much potassium to be in the body.

    Some "water pills" that increase potassium in the body include amiloride (Midamor), spironolactone (Aldactone), triamterene (Dyrenium), and others.



The appropriate dose of laminaria 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 laminaria. 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.

View References


  • Amster E, Tiwary A, Schenker MB. Case report: potential arsenic toxicosis secondary to herbal kelp supplement. Environ Health Perspect 2007;115:606-8. View abstract.
  • Atlas RO, Lemus J, Reed J 3rd, Atkins D, Alger LS. Second trimester abortion using prostaglandin E2 suppositories with or without intracervical Laminaria japonica: a randomized study. Obstet Gynecol. 1998 Sep;92(3):398-402 View abstract.
  • Covington TR, et al. Handbook of Nonprescription Drugs. 11th ed. Washington, DC: American Pharmaceutical Association, 1996.
  • Electronic Code of Federal Regulations. Title 21. Part 182 -- Substances Generally Recognized As Safe. Available at:
  • Eliason BC. Transient hyperthyroidism in a patient taking dietary supplements containing kelp. J Am Board Fam Pract 1998;11:478-80.
  • Fetrow CW, Avila JR. Professional's Handbook of Complementary & Alternative Medicines. 1st ed. Springhouse, PA: Springhouse Corp., 1999.
  • Foster S, Tyler VE. Tyler's Honest Herbal, 4th ed., Binghamton, NY: Haworth Herbal Press, 1999.
  • Harrell BL, Rudolph AH. Letter: Kelp diet: A cause of acneform eruption. Arch Dermatol 1976;112:560.
  • Jain JK, Mishell DR Jr. A comparison of misoprostol with and without laminaria tents for induction of second-trimester abortion. Am J Obstet Gynecol. 1996;175(1):173-7. View abstract.
  • Kathan RH. Kelp extracts as antiviral subatances. Ann N Y Acad Sci 1965;130:390-7.
  • Kazzi GM, Bottoms SF, Rosen MG. Efficacy and safety of Laminaria digitata for preinduction ripening of the cervix. Obstet Gynecol 1982;60:440-3.. View abstract.
  • Ko SJ, Kim J, Han G, et al. Laminaria japonica combined with probiotics improves intestinal microbiota: a randomized clinical trial. J Med Food. 2014 Jan;17(1):76-82. doi: 10.1089/jmf.2013.3054. View abstract.
  • McQuade M, Barbour K, Betstadt S, Harrington A. Intubation and intensive care after laminaria anaphylaxis in second-trimester abortion. Am J Emerg Med. 2020;38(1):163.e1-163.e2. View abstract.
  • Miyai K, Tokushige T, Kondo M; Iodine Research Group. Suppression of thyroid function during ingestion of seaweed "Kombu" (Laminaria japonoca) in normal Japanese adults. Endocr J. 2008 Dec;55(6):1103-8. Epub 2008 Aug 9. View abstract.
  • Norman JA, Pickford CJ, Sanders TW, Waller M. Human intake of arsenic and iodine from seaweed-based food supplements and health foods available in the UK. Food Addit Contam 1988;5:103-9.. View abstract.
  • Pye KG, Kelsey SM, House IM, et al. Severe dyserythropoeisis and autoimmune thrombocytopenia associated with ingestion of kelp supplement. Lancet 1992;339:1540. View abstract.
  • Tabasi Z, Mesdaghinia E, Abedzadeh-Kalahroudi M, Sehat M, Panahandeh A. Comparing the effects of vaginal misoprostol, laminaria, and extra amniotic saline infusion on cervical ripening and induction of labor. Obstet Gynecol Sci. 2020;63(3):261-269. View abstract.
  • Turnquest MA, Lemke MD, Brown HL. Cervical ripening: randomized comparison of intravaginal prostaglandin E2 gel with prostaglandin E2 gel plus laminaria tents. J Matern Fetal Med. 1997;6(5):260-3. View abstract.
  • 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: (Accessed 8 August 2006).
  • You JS, Sung MJ, Chang KJ. Evaluation of 8-week body weight control program including sea tangle (Laminaria japonica) supplementation in Korean female college students. Nutr Res Pract. 2009 Winter;3(4):307-14. doi: 10.4162/nrp.2009.3.4.307. Epub 2009 Dec 31. View abstract.

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