Equisetum hyemale is a perennial rush in the Equisetaceae family. It is native to England, North America, and Asia. Equisetum hyemale can be found in and around stream banks. In herbal medicine, the roots and stems are used to treat water retention problems, as a weight loss aid, and a host of other conditions. The medicinal uses of this plant have not been verified by the U.S. Food and Drug Administration. The herb is generally considered safe, but side effects have been reported.
This type of rush is commonly known as Dutch rush or horsetail. It grows best in U.S. Department of Agriculture Hardiness Zones 3-11. This means the lowest tolerable temperature is -40° Fahrenheit (-39.9° Celsius). Equisetum hyemale prefers full sun or very light shade and needs soil with a pH level between 6.1 and 7.5. The plant grows well in or near bodies of water.
Fresh or dried herb may be used medicinally. The stems are usually cut just above the root and then made into an extract. Herbalists sometimes recommend that clients ingest the ashes of the plant to relieve heartburn or stomach upset. Applying the extract to the eyelids may reduce swelling.
The November 1985 edition of the Journal of Ethnopharmacology suggested that Equisetum hyemale may be a strong diuretic in comparison with other species in its genus. This confirms what traditional healers have said for years. High doses of this diuretic herb may leach minerals from the bone, however, so caution is advised.
Despite the claims of herbalists and other natural medicine advocates, a European panel determined that there is no scientific data to indicate Equisetum hyemale helps with weight loss. In fact, some insist that this herb actually increases appetite. Those interested in using this herb as a weight loss aid may want to carefully review the data before buying it.
Equisetum hyemale is said to have anti-inflammatory, anti-bacterial, and cholesterol-lowering properties, but there is not enough evidence to definitively make these claims. This plant is sometimes used as a hair rinse and a remedy for fleas, lice, and mites. At times, this species of rush turns up on the dinner table as a substitute for asparagus.
Side effects of this herb are limited. Thiaminase, a naturally-occurring enzyme found in this plant, destroys vitamin B complex. For this reason, users may want to limit the amount of the raw herb they ingest. The enzyme may be killed when the plant is dried or cooked. Pregnant or nursing women and those with chronic illnesses may want to consult a healthcare provider before taking Equisetum hyemale to make sure it is safe for their particular situation.