Laminaria is a type of seaweed that is native to Japan. 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 for weight loss, high blood pressure, as a bulk laxative for constipation, and for treating radiation sickness. It is also used for preventing cancer.
Sometimes healthcare providers use laminaria to expand the cervix, the mouth of the uterus, before certain medical procedures. They place a layer of laminaria directly inside the cervix, the “neck” of the uterus. This layer of laminaria is sometimes called a “tent.” The purpose of the tent is to enlarge the cervix before “D&C,” also known as dilation and curettage (scraping of the uterus); removal of a medical device that is in the uterus; diagnostic procedures; placement of radium for cancer treatment; and other gynecological procedures. Laminaria tents are also used in pregnant women to “ripen” (expand) the cervix to make labor and delivery easier, and also to cause abortions during the first three months of pregnancy.
How it works
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.
Possibly IneffectivePreparation ("ripening") of the cervix in women, such as during childbirth or procedures
Although laminaria might speed up childbirth, it doesn't seem to reduce the number of women who need Cesarean sections to deliver. Laminaria also increases the chance of infection in both mother and infant.
Laminaria is POSSIBLY UNSAFE when taken by mouth. 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.
Pregnancy and breast-feeding: The use of laminaria directly on the cervix during pregnancy or childbirth isUNSAFE. It can cause seriousside effectsfor both mother and child, including infection,ruptureof the cervix, and infantdeath. Taking laminaria by mouth during pregnancy is alsoUNSAFEbecause laminaria canaffecthormones.
Taking laminaria by mouth during breast-feeding is LIKELY UNSAFE because laminaria might contain some poisonous chemicals.
If you are pregnant or breast-feeding, it's best to avoid laminaria.
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.
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).Potassium supplements
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.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
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)
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.