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nettle

What Is It?
Health Benefits
Forms

Dosage Information
Guidelines for Use

General Interaction

Possible Side Effects

Cautions

References

Evidence Based Rating Scale

What Is It?

Also known as "stinging nettle" because prickly hollow needles on the dark green leaves of this plant sting and burn upon contact, nettle (Urtica dioica, or Urtica urens) is an ancient herbal remedy for snakebites, asthma, arthritis, urinary tract infections, and excessive menstrual flow. While the above-ground parts of the plant--the leaf and the stem--are generally still used for these purposes, the roots, also known as Urtica radix, are now also popular for treating discomforts caused by an enlarged prostate.

This flowering perennial can be found growing wild in the wastelands of temperate zones including the United States, Canada and others. It is even used as a kitchen Herb in many parts of world. Luckily, drying or boiling the plant dissolves the painful bristles. Many people like to steam the leaves to eat like spinach, or to simmer them in soup. The young shoots are quite rich in Vitamins C and K, calcium, carotene, potassium, and silica.

Health Benefits

The herb and leaf have several known therapeutic qualities: They fight Inflammation, act as an Antihistamine, and have a Diuretic effect, meaning they increase production of urine. These properties make nettle potentially beneficial in treating urinary tract infections, seasonal allergies, and arthritis, as well as easing symptoms of premenstrual syndrome. The root has separate properties with potential benefit for prostate health. Other components may help to strengthen nails and stimulate hair growth.

Specifically, nettle may help to:

Fight urinary tract infections. As a diuretic, nettle tea helps to flush out bacteria and toxins in the urinary tract during infection. And the anti-inflammatory properties of nettle may help to soothe inflamed tissues in the bladder. Drinking nettle leaf tea has become popular in Europe for treating bladder infections and other inflammations of the lower urinary tract. Commission E (the German equivalent of an FDA for herbs) has approved nettle for this use. (1) While no scientific trials in the United States have tested the use of nettle for these infections, several alternative medicine resources recommend it for this use. (2-4)

Treat prostate problems. Nettle root appears to be particularly useful for men with benign prostatic hyperplasia (BPH), a condition in which the prostate gland gradually enlarges and narrows the urethra that drains urine from the bladder ultimately causing difficulties with urination. A number of studies using extracts made specifically from nettle root (not the stems or leaves) have demonstrated improved quality of life, increased urinary output and peak urinary flow compared to placebo. Additionally Serum Hormone Binding Globulin (SHBG) was decreased suggesting modification of hormonal effects on the prostate. (5) Nettle root extract, when blended with an extract of the herb Pygeum africanum, may also inhibit the hormonal changes that lead to BPH. In fact, herbal remedies for prostate enlargement frequently combine these herbs along with Saw palmetto, another natural substance that has shown great promise in controlling BPH symptoms. A 2000 study comparing an herbal combination of Saw palmetto berry and nettle root, called Prostagutt® forte (also known as PRO 160/120), to the conventional medication finasteride (Proscar®, Propecia®) found the herbal remedy was equally effective in relieving symptoms of BPH and was better tolerated. (6) In a 2005 study of 257 men with BPH, subjects received either PRO 160/120 or placebo. Those treated with the PRO 160/120 reported a substantially larger reduction in a total score for measures of urinary function including urinary output, duration of flow, residual urinary volume, and size of prostate after 24 weeks of double-blind treatment compared to subjects in the placebo group. (7) Nettle root may work by slowing the growth of the prostate, but more research is needed. Consult a physician before taking nettle root for BPH to ensure a proper diagnosis and rule out prostate cancer.

Reduce seasonal allergy (hay fever) symptoms. Familiar hay fever symptoms--nasal congestion, sneezing, itching, watery eyes--are triggered by an immune-system overreaction to airborne particles (allergens) such as pollen and ragweed. Nettle leaf may help minimize hay fever discomforts by supplying compounds that inhibit the release of Histamine, the inflammatory substance triggered by these allergens.

Unfortunately, there has been very little research on the value of nettle for hay fever sufferers. In one clinical trial, however, more than half of the hay fever sufferers taking nettle (in freeze-dried form) reported moderate to excellent relief from allergy symptoms, such as sneezing and itching. In contrast, less than 40% of those taking a Placebo felt any better. Starting nettle at the first sign of symptoms seems to provide the most improvement. (8) A 2009 laboratory study provided evidence for the first time that nettle inhibits the release of histamine suggesting a mechanism for improving seasonal allergy symptoms. (9) More research is needed to confirm or refute these effects.

Reduce pain in arthritis. Arthritis sufferers may benefit from nettle's anti-inflammatory actions. In fact, nettle leaf Extract is a Native American folk remedy for rheumatic pains. Topical formulations of nettle herb juice have also been used to treat joint pain. There is now evidence that taking the herb along with a prescription arthritis drug (diclofenac was used in one study) enables arthritis sufferers to reduce the dosage of prescription medication. (10) And a preliminary study of 27 subjects with osteoarthritis using topical nettle stings for 30 seconds twice daily for a week to treat pain at the base of the thumb or index finger for twelve weeks found significant improvements in pain and disability compared to placebo, after one week of treatment. (11) More research is needed.

Ease premenstrual syndrome symptoms. The herb is being explored as a treatment for symptoms of premenstrual syndrome (PMS). Researchers believe properties of nettle may help to reduce the premenstrual bloating (fluid retention) that many women develop before their periods. (12) However, research is lacking. Clinical studies are needed to determine efficacy.

Strengthen nails and hair. Because nettle is rich in silica and other minerals important for nail and hair growth, drinking a cup of nettle leaf tea daily may help to nourish and strengthen nails, as well as to combat hair loss and stimulate hair growth. However, clinical studies have not examined these potential benefits. Research is needed.

Urtica urens is also used as a homeopathic medicine where, according to the Principle of Similars, it is used for hives and for pains that are burning and stinging wherever they occur as well as for other indications. Please see the WholeHealthMD entry on Homeopathy for more information about how homeopathic uses may differ from typical uses of herbal medicines.

Forms

  • Tincture
  • liquid extract
  • fresh juice
  • dried herb/tea
  • capsule
  • homeopathic pellets         

Dosage Information

Special tip: When buying nettle supplements, make sure to differentiate nettle leaf from nettle root because they are used differently. Try to purchase either one in a freeze-dried form or as a Standardized extract.

  • For urinary tract infections: Drink several cups of nettle leaf tea daily. To make the tea, use 2 teaspoons of dried nettle leaf for each 8 ounces of water. Pour very hot (not boiling) water over the herb, steep for ten minutes, and then strain.

  • For prostate problems: Take 600-1200mg of nettle root extract or 80 to 120 mg of the specific combination extract (WS 1031) twice a day in conjunction with other prostate-healthy herbs such as Saw palmetto (160 mg twice a day) and Pygeum africanum (100 mg twice a day.)

  • For seasonal allergies: Take a 250 mg to 300 mg freeze-dried nettle leaf capsule containing the standardized extract three times a day on an empty stomach or before going into a known allergenic environment.

  • For arthritis: Apply fresh stinging nettle leaf to painful joints for 30 seconds twice a day, or take three to six grams of crude stinging nettle leaf three times a day.

  • For PMS: Drink about three cups of nettle leaf tea daily during period of bloating.

  • For Nail and Hair problems: No dosage has been established, but applying an extract of stinging nettle to the scalp has been used to stimulate hair growth. And 50-100 mg of oral nettle leaf daily has been used orally.  

Be sure to check out our Dosage Recommendations Chart for Nettle, which has therapeutic dosages for specific ailments at a glance.

Guidelines for Use

  • Except when treating hay fever, which responds best to nettle taken on an empty stomach, take this herb (or root) with food to lessen the risk of stomach upset.

  • As a diuretic, nettle leaf promotes urination. To avoid dehydration and a healthy balance of body fluids, be sure to drink plenty of liquids throughout the day while taking nettle.

  • Keep in mind that the root of the nettle plant is the only form effective for prostate problems. When treating any other ailment, select a product made from the leaf or other above-ground part of the nettle plant. 

General Interaction

There are no known drug or nutrient interactions associated with nettle root.

Although no adverse event have been reported, the leaf and other above-ground parts of the plant contain compounds that could, theoretically, cause unwanted interactions with certain medications. Consult your doctor before combining these forms of nettle with the following medications:

  • Anticoagulants (blood-thinners) might be less active with nettle because of the large amounts of vitamin K in the leaves.

  • Diabetes drugs in usual doses may be insufficient as there is some evidence that nettles may increase blood sugar.

  • Blood pressure medications in usual doses may cause hypotension as there is some evidence that nettles may lower blood pressure. 

Please see the WholeHealthMD drug interaction tables for specific drugs in these categories. 

Possible Side Effects

Nettle is considered safe at commonly recommended dosages. Occasionally, preparations from the root, in particular, can cause mild indigestion, diarrhea, or other stomach upset. Taking nettle with food may lessen the risk of these reactions. 

Skin redness and irritation may develop if you apply nettle topically or accidentally touch the above-ground parts of the plant before they have been dried or otherwise treated. 

Cautions

  • Stick to commonly recommended dosages for this herb.

  • Don't stop taking a prescription medication and start taking nettle root for prostate problems without first discussing the change with your doctor.

  • If you have diabetes, consult your doctor about taking nettle; although not reported in humans, recent animal studies indicate that the herb may increase blood sugar levels.

  • Don't take nettle if you are pregnant or breast-feeding.

  • Consult your doctor before taking nettle leaf for swelling or other fluid retention associated with potentially serious disorders such as impaired heart or kidney function. 

References 

1. Blumenthal M, Busse WR, Goldberg A, et al. (eds). The complete German Commission E Monographs: Therapeutic Guide to Herbal Medicines. Austin: American Botanical Council and Boston: Integrative Medicine Communications. 1998, 428.
2. Herbs 2000. "Urinary Tract Infection." Accessed at http://www.herbs2000.com/disorders/urinary_inf.htm. on November 14, 2009.
3. MotherNature.com. "Bladder Infections." Accessed at http://www.mothernature.com/Library/Bookshelf/Books/41/19.cfm on November 15, 2009.
4. University of Michigan Health System. Healthwise Knowledgebase. "Nettle."
5. Schulz V, Hansel R, Blumenthal M, Tyler VE. Rational Phytotherapy: A Reference guide for Physicians and Pharmacists. Fifth edition, Springer, New York, 2004.
6. Sokeland J. Combined sabal and urtica extract compared with finasteride in men with benign prostatic hyperplasia: analysis of prostate volume and therapeutic outcome. BJU Int. 2000;86:439-42.
7. 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 Jun 1; [Epub ahead of print].
8. Mittman P. Randomized, double-blind study of freeze-dried Urtica dioica in the treatment of allergic rhinitis. Planta Med. 1990;56:44-7.
9. Roschek B Jr, Fink RC, McMichael M, Alberte RS. Nettle extract (Urtica dioica) affects key receptors and enzymes associated with allergic rhinitis. Phytother Res. 2009 Jul;23(7):920-6.
10. Mills S, Bone K. Principles and Practice of Phytotherapy. London: Churchill Livingstone, 2000.
11. Randall C, Randall H, Dobbs F, et al. Randomized controlled trial of nettle sting for treatment of base-of-thumb pain. J R Soc Med. 2000 Jun;93(6):305-9.
12. Loecher B, O'Donnel SA, and Editors of Prevention Magazine. New choices for healing in women. Emmaus, PA: Rodale Press. 1997;172.

Evidence Based Rating Scale

The Evidence Based Rating Scale is a tool that helps consumers translate the findings of medical research studies and what our clinical advisors have found to be efficacious in their personal practice into a visual and easy to interpret format. This tool is meant to simplify the information on supplements and therapies that demonstrate promise in the treatment of certain conditions.

 

Condition

Rating

Explanation

 

Allergies

   

Preliminary evidence indicates efficacy in reducing symptoms. More research is needed. (8, 9)

Arthritis  

Preliminary evidence indicates potential to lessen conventional treatment dosage in arthritis, and to improve pain and disability in osteoarthritis. More research is needed. (10, 11)

Hair problems  

Evidence is lacking. Research is needed to determine efficacy.

Nail problems   Date Published: 04/19/2005
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