by EBSCO CAM Review Board

Supplement Forms/Alternate Names:

  • Bladder wrack; Fucus vesiculosis


Bladderwrack is type of brown seaweed named for the bladder-like air pockets along its leaves. It can be taken as an extract, pill, or powder.


There aren’t any advised doses for bladderwrack.

What Research Shows

There is not enough data to support that bladderwrack is helpful in treating health problems. We will review future studies as they are published.

Editorial process and description of evidence categories can be found at EBSCO NAT Editorial Process.

Safety Notes

It may be safe to take small doses of bladderwrack for a short period of time. It may contain iodine and add to thyroid problems and raise the risk of thyroid cancer. People with iodine allergy, thyroid problems, and women who are pregnant or breastfeeding should not take bladderwrack. Not enough studies have been done to say whether it is safe to take for a long period.


Talk to your doctor about any supplements or therapy you would like to use. Some can interfere with treatment or make conditions worse, such as:

  • People taking medicine to slow or prevent blood clots should talk to their doctor before taking bladderwrack. It may increase the risk of bleeding.


Michikawa T, Inoue M, et al. Seaweed consumption and the risk of thyroid cancer in women: the Japan Public Health Center-based Prospective Study. Eur J Cancer Prev. 2012 May;21(3):254-260.

Revision Information

  • Reviewer: EBSCO CAM Review Board
  • Review Date: 03/2019
  • Update Date: 02/10/2020