Yarrow

Scientific Name(s): Achillea millefolium L.
Common Name(s): Green arrow, Milenrama, Milfoil, Millefolli herba, Nosebleed plant, Thousand-leaf, Wound wort, Yarrow

Clinical Overview

Use

Clinical studies are limited.

Dosing

Traditionally, yarrow herb 4.5 g/day has been used for various conditions. However, there are no quality clinical studies to validate this dosing.

Contraindications

Yarrow use is contraindicated in known allergies to any members of the Aster family. Data for reported contraindications in epilepsy are lacking.

Pregnancy/Lactation

Avoid use. Documented adverse effects.

Interactions

None well documented.

Adverse Reactions

Contact dermatitis is the most commonly reported adverse reaction, but high doses may be associated with anticholinergic effects.

Toxicology

Yarrow is not generally considered toxic; however, an antispermatogenic effect has been reported, and safety data are insufficient to support use of the herb in cosmetic products.

Scientific Family

  • Asteraceae (daisy)
  • Compositae (aster)

Botany

The name yarrow applies to approximately 80 species of daisy plants native to the north temperate zone. A. millefolium L. has finely divided leaves and white, pink, or red flowers. It can grow up to 1 m in height. This hardy perennial weed has invasive fibrous rhizomes and blooms from June to November. The whole aerial plant part is used medicinally. Golden yarrow belongs to a distinct genus in the Aster family, Eriophyllum confertiflorum. Yarrow is a member of the daisy (Asteraceae) family that includes aster, chamomile, chrysanthemum, feverfew, ragweed, sunflower, and tansy.

History

The use of yarrow in food and medicine dates back at least to 1200 BC. The genus name Achillea is derived from the Greek myth of Achilles who was said to carry A. millefolium (also known in antiquity as herba militaris) into battle to treat wounds. Yarrow leaves have been used for tea, and young leaves and flowers have been used in salads. Infusions of yarrow have served as cosmetic cleansers and medicines. Sneezewort leaves (Achillea ptarmica) have been used in sneezing powder, while those of A. millefolium have been used for snuff. Yarrow has been used as a "strengthening bitter tonic" and astringent. The fresh leaves have been used to relieve toothaches and to heal wounds, and may have anti-inflammatory effects. Fresh yarrow and dried herb are also used in China for dog and snake bites and to alleviate menstrual bleeding. 

Chemistry

The constituents of yarrow have been reviewed in detail, particularly the essential oil. The plant yields approximately 1% essential oil containing azulene, alpha and beta pinenes, borneol, cineole, and other compounds including chamazulene (also found in chamomile) and trace amounts of thujone, although the composition varies. Other constituents identified include sesquiterpene lactones, flavonoids, tannins, sterols, alkanes, and fatty acids, among others. 

Uses and Pharmacology

Antimicrobial/Antiprotozoal activity

In vitro studies have shown that the essential oil of yarrow possesses limited antibacterial and antiviral (Newcastle disease virus) activity. Because of the association of Helicobacter pylori with gastritis, peptic ulcer, and gastric cancer, in vitro experimentation was conducted in H. pylori-infected gastric epithelial cells with 24 medicinal plants indigenous to Pakistan to evaluate their effect on secretion of interleukin (IL)-8 and generation of reactive oxygen species (ROS) in order to assess anti-inflammatory and cytoprotective effects. Although no significant direct cytotoxic effects on the gastric cells or bactericidal effects on H. pylori were found, yarrow was observed to have mild and moderate inhibitory activity on IL-8 at 50 and 100 mcg/mL, respectively, and significant suppression on ROS generation in H. pylori-infected gastric cells. 

Animal data

Activity against trypanosomes, Leishmania, and malarial parasites has also been demonstrated, and yarrow’s role in protection against gastric ulcers has been examined in rats. Insect repellent activity has also been demonstrated. 

Clinical data

Research reveals no clinical data regarding the use of yarrow extracts in infectious diseases.

Cancer

Animal data

The cytotoxicity of yarrow extracts has been examined. In vitro studies suggest that the activity of casticin, sesquiterpene compounds, and other extracts exerts apoptotic and antitumor activity against various human cancer cell lines. 

Clinical data

Current research reveals only inconclusive clinical data regarding the use of yarrow extracts in cancer. A study evaluated the additive effect of A. millefolium (12 ppm distillate mixed with standard therapy mouthwash) in oral mucositis in 56 patients with cancer for 14 days, and found clinically significant healing rates. 

Cardiovascular

Animal data

An effect on rat vascular smooth muscle cells has been demonstrated in vitro. The flavonoid artemetin extracted from A. millefolium was hypotensive in normotensive rats. Diuretic effects of certain yarrow extracts have also been demonstrated. Other studies have demonstrated hypotensive effects in rats, as well as negative inotropic and chronotropic effects of crude yarrow extracts in isolated guinea pig atrial tissue. 

Clinical data

Research reveals no clinical data regarding the use of A. millefolium in cardiovascular conditions; however, a related plant, Achillea wilhelmsii, produced antihypertensive and lipid-modifying effects in a clinical study. 

Renal effects

Animal data

A study evaluating orally administered extracts of A. millefolium for diuretic effects in rats found that diuresis was effectively increased. The study found the effect to depend on both the activation of bradykinin B2 receptors and the activity of cyclooxygenases. Extracts of the plant have also been shown to protect against induced nephrolithiasis in rats. Additionally, antioxidant effects have been demonstrated in rat systems, including the kidney. 

Clinical data

Administration of the aerial plant parts of A. millefolium were studied in a clinical trial involving patients with chronic kidney disease. Reductions in plasma nitrite and nitrate content were observed and compared with placebo; however, statistical significance was not reached. 

Other uses

Traditional uses as a hemostatic agent and for cerebral and coronary thrombosis are without clinical validation. In one study, A. millefolium tea consumed 3 times daily for 3 days reduced pain severity in primary dysmenorrhea. 

Anti-inflammatory activity has been described in animal and in vitro studies. Anxiolytic effects in mice have also been described. 

Dermatological applications have been evaluated. Wound healing has been studied in rodents; however, clinical studies are lacking. 

Relaxant effects on smooth muscle tissue have been studied in animals. 

Dosing

Traditionally, yarrow herb 4.5 g/day has been used for various conditions, including inflammatory disorders appetite loss, and dyspepsia. However, there are no quality clinical studies to validate this dosing.

Pregnancy / Lactation

Avoid use. Although present in small amounts, thujone is an abortifacient. Toxic reproductive effects in rats have not been proven. 

Interactions

None well documented. Interactions may occur with diuretic medicines. 

Adverse Reactions

Contact dermatitis is the most commonly reported adverse reaction from yarrow, and its use is contraindicated in known allergies to any members of the Aster family. Data for reported contraindications in epilepsy are lacking. One case report exists documenting anticholinergic adverse effects associated with the consumption of 5 cups of yarrow tea per day for a 1 week. 

Toxicology

Yarrow is not generally considered toxic; however, an antispermatogenic effect has been reported.1Safety data are insufficient to support safe use of the herb in cosmetic products. Weak genotoxicity has been reported, and toxic reproductive effects in rats have not been proven. 

Commercial preparations must be thujone-free because, although present in small amounts in yarrow, thujone is anabortifacient.