goldenseal
n. a shrub, Hydrastis canadensis, with medicinal properties. Indigenous to the eastern United States, it has a long history as a folk remedy to control uterine bleeding, and its leaves are commonly used as a poultice and antibacterial agent. There are few clinical studies evaluating the efficacy of goldenseal, but its active ingredients, the alkaloids berberine and hydrastine, have been studied extensively. Berberine has been shown to have antimicrobial properties and may also be effective in preventing the growth of cancer cells. Hydrastine has vasoconstrictive and abortifacient effects and, when taken orally, has been shown to induce labor in pregnant women. At recommended doses, goldenseal appears to have minimal adverse effects (e.g., irritation of the mouth, throat, and stomach; tingling of the skin), but at higher doses it may cause hypertension and increase heart rate; it has also been associated with seizures and other evidence of overstimulation
of the central nervous system, and at very high doses may be toxic, potentially causing paralysis, respiratory failure, and death. Chronic long-term use may inhibit vitamin B absorption. Additionally, goldenseal may interact with other agents, including anticoagulants, antihypertensives, and drugs metabolized by the cytochrome P450 3A4 enzyme (e.g., clonidine, nefazodone, St. John’s wort).