Blue Flag


Blue flag is a flower that grown in North America and parts of Northern Europe. The root and flower have been used to ease digestion and promote liver health. Blue flag can be taken as an extract, pill, or powder.


There are no advised doses for blue flag.

What Research Shows

There is not enough data to support that blue flag 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 blue flag in small amounts for a short period, but nausea and vomiting may happen. Large amounts may not be safe. Not enough studies have been done to say whether it is safe to take for a long period. Women who are pregnant or breastfeeding and children should not use blue flag.


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


1. Blue flag. Natural Resources Conservation Service—United States Department of Agriculture website. Available at: Accessed February 17, 2020.

Last reviewed August 2019 by EBSCO CAM Review Board
Last Updated: 2/14/2020

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