Anyone who lives in a locale where nettle grows wild will eventually discover the powers of this dark green plant. Depending on the species, the fine hairs on its leaves and stem cause burning pain that lasts from hours to weeks. But this well-protected herb has also been used as medicine. Nettle juice was used in Hippocrates' time to treat bites and stings, and European herbalists recommended nettle tea for lung disorders. Nettle tea was used by Native Americans as an aid in pregnancy, childbirth, and nursing.
What Is Nettle Used for Today?
Currently, nettle root is more commonly used medicinally than the above-ground portion of the herb. In Europe, nettle root is widely used for the treatment of benign prostatic hyperplasia (BPH) , or prostate enlargement. Like saw palmetto, pygeum, and beta-sitosterol, nettle appears to reduce obstruction to urinary flow and decrease the need for nighttime urination. However, the evidence is not as strong for nettle as it is for these other treatments.
Note: Before self-treating prostate symptoms with nettle root, be sure to get a proper medical evaluation to rule out prostate cancer.
Nettle leaf has become a popular treatment for allergies (hay fever) based on one preliminary double-blind study.
Nettle leaf is highly nutritious and, in cooked form, may be used as a general dietary supplement.
What Is the Scientific Evidence for Nettle?
The evidence is much better for nettle root and prostatic enlargement than for nettle leaf and allergies.
In a double-blind, placebo-controlled study performed in Iran, 558 people were given either placebo or nettle root for 6 months. 21 The results indicated that nettle root is significantly more effective than placebo on all major measures of BPH severity. Benefits were seen in three other double-blind studies as well, enrolling a total of more than 150 men. 7 -9
There are theoretical reasons to believe that nettle root's effectiveness might be enhanced when it is combined with another herb used for prostate problems: pygeum . 12,13 Nettle has also been studied in combination with saw palmetto, with mixed results. 14,15,22
Nettle root contains numerous biologically active chemicals that may influence the prostate indirectly by interacting with sex hormones, or directly by altering the properties of prostate cells. 1-5,18-20
One small double-blind study suggests that direct application of stinging nettle leaf to a painful joint may improve symptoms. 11
Dosages of nettle root extract vary according to preparation, and we recommend following label instructions. Some nettle root products are standardized to their content of the substance scopoletin, but since this substance is not established as an active ingredient, the significance of this standardization remains unclear.
For allergies, the studied dosage is 300 mg twice a day of freeze-dried nettle leaf.
Because nettle leaf has a long history of food use, it is believed to be safe.
Nettle root does not have as extensive a history to go by. Although detailed safety studies have not been reported, no significant adverse effects have been noted in Germany where nettle root is widely used. In practice, it is nearly side-effect free. In one study of 4,087 people who took 600 to 1,200 mg of nettle root daily for 6 months, less than 1% reported mild gastrointestinal distress and only 0.19% experienced allergic reactions (skin rash). 16
For theoretical reasons, there are some concerns that nettle may interact with diabetes, blood pressure, anti-inflammatory, and sedative medications, although there are no reports of any problems occurring. 17
The safety of nettle root or leaf for pregnant or nursing mothers has not been established, and there are concerns based on animal studies and its traditional use for inducing abortions. 18 However, nettle leaf tea is a traditional drink for pregnant and nursing women.
1. Hryb DJ, Khan MS, Romas NA, et al. The effect of extracts of the roots of the stinging nettle ( Urtica dioica ) on the interaction of SHBG with its receptor on human prostatic membranes. Planta Med . 1995;61:31-32.
7. Vontobel HP, Herzog R, Rutishauser G, et al. Results of a double-blind study on the effectiveness of ERU (extractum radicis Urticae) capsules in conservative treatment of benign prostatic hyperplasia [translated from German]. Urologe A . 1985;24:49-51.
8. Dathe G, Schmid H. Phytotherapy of benign prostate hyperplasia (BPH); double-blind study with stinging nettle root extract (Extractum Radicis Urticae - ERU) [translated from German]. Urologe B . 1987;27:223-226.
12. Hartmann RW, Mark M, Soldati F. Inhibition of 5 alpha-reductase and aromatase by PHL-00801 (Prostatonin), a combination of PY 102 (Pygeum africanum) and UR 102 (Urtica dioica) extracts. Phytomedicine. 1996;3:121-128.
13. Krzeski T, Kazon M, Borkowski A, et al. Combined extracts of Urtica dioica and Pygeum africanum in the treatment of benign prostatic hyperplasia: double-blind comparison of two doses. Clin Ther. 1993;15:1011-1020.
20. Lichius JJ, Lenz C, Lindemann P, et al. Antiproliferative effect of a polysaccharide fraction of a 20% methanolic extract of stinging nettle roots upon epithelial cells of the human prostate (LNCaP). Pharmazie . 1999;54:768-771.
22. Lopatkin N, Sivkov A, Walther C, et al. Long-term efficacy and safety of a combination of sabal and urtica extract for lower urinary tract symptoms a placebo-controlled, double-blind, multicenter trial. World J Urol. 2005 June 1. [Epub ahead of print]
Last reviewed October 2007 by EBSCO CAM Review Board
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