Herbs & Supplements:
Nettle
Urtica dioica
Principal Proposed Uses
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Benign Prostatic Hyperplasia (Nettle Root), Allergies (Nettle Leaf)
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 can also serve 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?
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 with nettle, be sure to get a proper medical evaluation to rule out prostate cancer.
Nettle leaf has recently become a popular treatment for allergies (hay fever) based on one preliminary 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.
Nettle Root
The use of nettle root for treating benign prostatic hyperplasia has not been as well studied as saw palmetto, but the evidence is at least moderately convincing.
Nettle root contains numerous biologically active chemicals that may influence the function of the prostate, interact with sex hormones, slow the growth of prostate cells, fight prostate cancer, and reduce inflammation.1–5
Open studies involving a total of over 15,000 men with BPH have found significant improvements in prostate size, nighttime urination, urination frequency, urine flow, and residual urine.6 However, open studies are not necessarily reliable in this case because up to 60% of men with BPH show good responses to placebo.
A double-blind placebo-controlled study of 50 men over 9 weeks found a significant increase in urination volume and urine flow rate.7 In another double-blind placebo-controlled study, treatment of 67 men with nettle produced a 14% improvement in urine flow and a 53% decrease in residual urine.8 Finally, a double-blind placebo-controlled study of 40 men found a significant decrease in frequency of urination after 6 months.9
Nettle Leaf
A preliminary double-blind placebo-controlled study following 69 individuals suggests that freeze-dried nettle leaf may at least slightly improve allergy symptoms.10
One small double-blind study suggests that direct application of stinging nettle leaf to a painful joint may improve symptoms.11
Dosage
According to Commission E, the proper dosage of nettle root is 4 to 6 g daily of the whole root, or a proportional dose of concentrated extract. There is some reason to believe that nettle root's effectiveness might be enhanced when it is combined withanother herb used for prostate problems, pygeum.12,13 Nettle is also sometimes combined with saw palmetto, and such combinations have been found effective.14,15
For allergies, the proper dosage is 300 mg twice a day of freeze-dried nettle leaf.
Safety Issues
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 also a traditional drink for pregnant and nursing women.
Interactions You Should Know About
If you are taking anti-inflammatory, antihypertensive, sedative, or blood sugar–lowering medications, nettle might conceivably interact with them, although it is unlikely.
View References
Last reviewed March 2002 by Medical Review Board
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