Related Terms

• American blue flag, beta-sitosterol fatty acids, blue flag iris, clajeux (French), dagger flower, dragon flavonoids, flower, flag lilly, flag lily, fleur-de-lis (French), flower-de-luce (French), furfural, gum, harlequin blueflag, Iridaceae (family), iridin, irigenin, Iris caroliniana Watson, Iris versicolor, iris versicolore (French), irisin, isoflavonoids, isophthalic acid, kosatec strakat (Slovak), Lis met Bontkleurige Bloem (Dutch), liver lily, oleoresin, phytosterols, poison flag, purple flag, salicylic acid, sciatica, snake lily, tannin, triterpenoids, water flag, water iris, wild iris.

Background

• Blue flag is a species of iris, which commonly grows in moist meadows, marshes, and along stream banks in northern North America. The root or rhizome is the part most often used and is the source of the iridin, also known as irisin. Iridin is usually used as a powdered extract that is bitter and nauseating and has diuretic and laxative properties.

• The blue flag rhizome has a very slight but peculiar odor, and a pungent, unpleasant taste. When used internally, fresh blue flag produces nausea, vomiting, purging, and gastrointestinal cramping. The dried root is less acrid and is traditionally employed as an emetic, diuretic, and cathartic. It has also been used for syphilis, some scrofula (tuberculosis infection of the neck lymph glands), skin disorders, and dropsy (edema).

• Currently, blue flag is frequently used topically for skin conditions, such as impetigo, eczema, and psoriasis. It is also used for detoxification by increasing urination, stimulating bile production, and acting as a laxative. Various Native American tribes have had many uses for blue flag including for lymphatic or kidney cancer.

• There are currently no high quality studies on the medicinal applications of blue flag. Clinical trials are needed to define the efficacy and safety of blue flag.

Scientific Evidence

Tradition/Theory

The below uses are based on tradition or scientific theories. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious and should be evaluated by a qualified health care professional.

• Angina, anti-inflammatory, astringent, bile secretion problems, blood purification, bruises, burns, cancer, cholera, circulatory stimulant, colds, constipation, diaphoretic (promotes sweating), diuretic, dropsy, earache, eczema, emetic (induces vomiting), emmenagogue (promotes menstruation), enlarged glands, enteritis, exhaustion, expectorant, eyewash, fistulas, freckle-removing, gallbladder disorders, gastritis, goiter, headaches, heartburn, impetigo, intestinal worms, jaundice, laxative, liver cleanser, liver conditions, lung inflammation, migraine, nausea and vomiting of pregnancy, pain, poisoning, prostate conditions, psoriasis, respiratory problems, saliva stimulant, sinus problems, skin disorders, skin pigmentation disorders, sores, splenic disorders, stimulant, syphilis, tinea pedis (athlete's foot), tuberculosis (scrofula), tumor, ulcers, vomiting, wound healing.

Dosing

The below doses are based on scientific research, publications, traditional use, or expert opinion. Many herbs and supplements have not been thoroughly tested, and safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients, even within the same brand. The below doses may not apply to all products. You should read product labels, and discuss doses with a qualified healthcare provider before starting therapy.

Adults (18 years and older)

• Based on available scientific evidence, there is no proven safe or effective dose for blue flag. According to expert opinion, fresh rhizome should only be applied on the skin and never taken by mouth, as it may irritate the mouth and is much more likely to cause nausea and diarrhea. Various forms of blue flag have been used, including decoctions, dried rhizomes, fluid extracts, powdered roots, solid extracts and tinctures.

Children (younger than 18 years)

• Based on available scientific evidence, there is no proven safe or effective dose for blue flag and this herb is not recommended in children.

Safety

The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.

Allergies

• Avoid in individuals with a known allergy or hypersensitivity to blue flag.

Side Effects and Warnings

• Safety information is based on traditional health practice patterns and expert opinion; there is a lack of available scientific human evidence demonstrating safety or efficacy of blue flag. Several poisonings after the consumption of blue flag have been reported; however, the severity or details of the poisonings is not clear. Blue flag is known to cause nausea, abdominal pain, cramping and vomiting. Avoid large oral doses in patients with neurological/CNS disorders, as large doses of blue flag may cause nerve pain.

• The sap of the plant may cause dermatitis in sensitive patients. The root is acrid and may cause skin rash or skin eruptions.

• Blue flag is not recommended in patients who are pregnant or breastfeeding, or in children. This herb is also likely unsafe when used in patients with gastrointestinal disorders or neurological disorders or allergies to blue flag.

• Blue flag is possibly safe when used in homeopathic doses for a short period of time and when applied in small amounts on the skin.

Pregnancy and Breastfeeding

• Pregnancy and lactation information is based on traditional health practice patterns and expert opinion; there is a lack of available reliable human trials demonstrating safety of blue flag. Expert opinion does not recommend blue flag for use during pregnancy or breastfeeding.

Interactions

Most herbs and supplements have not been thoroughly tested for interactions with other herbs, supplements, drugs, or foods. The interactions listed below are based on reports in scientific publications, laboratory experiments, or traditional use. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy.

Interactions with Drugs

• Interaction information is based on traditional health practice patterns and expert opinion; human evidence demonstrating interactions of blue flag with other substances is currently lacking in the available literature. Before taking blue flag, individuals should consult with a healthcare professional, including a pharmacist.

• Blue flag may have anti-inflammatory and diuretic (increasing urine flow) properties. Caution is advised when using other drugs with these effects.

• Blue flag may cause nausea and vomiting, and caution is advised when taking other drugs taken my mouth as metabolism may be altered. Blue flag may also cause gastrointestinal cramping and catharsis. Caution is advised when taking laxatives.

Interactions with Herbs and Dietary Supplements

• Interaction information is based on traditional health practice patterns and expert opinion; human evidence demonstrating interactions of blue flag with other substances is currently lacking in the available literature. Before taking blue flag, individuals should consult with a healthcare professional, including a pharmacist.

• Blue flag may have anti-inflammatory and diuretic (increasing urine flow) properties. Caution is advised when using other herbs and supplements with these effects.

• Blue flag may cause nausea and vomiting, and caution is advised when taking other herbs or supplements taken by mouth as metabolism may be altered. Blue flag may also cause gastrointestinal cramping and catharsis. Caution is advised when taking herbs and supplements with laxative effects, such as psyllium or aloe.

• Iron absorption may also be affected when taking blue flag due to its tannin content. Caution is advised in patients taking iron supplements or other multivitamins.

Author Information

• This information is based on a systematic review of scientific literature edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).

References

Natural Standard developed the above evidence-based information based on a thorough systematic review of the available scientific articles. For comprehensive information about alternative and complementary therapies on the professional level, go to www.naturalstandard.com. Selected references are listed below.

1. Note: Information in this monograph is based on traditional health practice patterns and expert opinion; there are no available reliable human trials demonstrating safety or efficacy of blue flag.