Common name: Stinging nettle
Botanical name: Urtica dioica
© Steven Foster
Parts used and where grown
Nettle is a leafy plant that is found in most temperate regions of the world. The Latin
root of Urtica is uro, meaning “I burn,” indicative of the small
stings caused by the little hairs on the leaves of this plant that burn when contact is made
with the skin. The root and leaves of nettle are used in herbal medicine.
Nettle has been used in
connection with the following conditions (refer to the individual
health concern for complete information):
Historical or traditional use (may
or may not be supported by scientific studies)
Nettle has a long history of use. The tough fibers from the stem have been used to make
cloth and cooked nettle leaves were eaten as vegetables. From ancient Greece to the present,
nettle has been documented for its traditional use in treating coughs, tuberculosis, and arthritis and in stimulating
hair growth.
Active constituents
There has been a great deal of controversy regarding the identity of nettle’s active
constituents. Currently, it is thought that polysaccharides (complex sugars) and lectins are
probably the active constituents. Test tube studies suggest the leaf has anti-inflammatory
actions. This is thought to be caused by nettle preventing the body from making inflammatory
chemicals known as prostaglandins.1 Nettle’s root affects hormones and
proteins that carry sex hormones (such as testosterone or estrogen) in the human body. This
may explain why it helps benign prostatic
hyperplasia (BPH).2 Although less frequently used alone like saw palmetto or pygeum, some limited clinical trials suggest benefit
of nettle root extract for men with milder forms of BPH.3
A preliminary trial reported that capsules made from freeze-dried leaves reduced sneezing
and itching in people with hay
fever.4 Further studies are needed to confirm this finding, however.
The historical practice of intentionally applying nettle topically with the intent of
causing stings to relieve arthritis has been assessed by a questionnaire in modern
times.5 The results found intentional nettle stings safe, except for a sometimes
painful, sometimes numb rash that lasts 6–24 hours. Additional trials are required to
determine if this practice is therapeutically effective.
How much is usually taken?
During the allergy season, two to three 300
mg nettle leaf capsules or tablets or 2–4 ml tincture can be taken three times per day.
For BPH, 120 mg of a concentrated root extract
in capsules can be taken two times per day.6 Many products for BPH will combine
nettle root with saw palmetto or pygeum extracts. Intentional stinging with nettles
should only be undertaken after consultation with a physician knowledgeable in botanical
medicine.
Are there any side effects or interactions?
Nettle may cause mild gastrointestinal upset in some people. Although allergic reactions to
nettle are rare, when contact is made with the skin, fresh nettle can cause a rash secondary
to the noted stings.7 Nettle leaf is considered safe for use in pregnancy and breast-feeding.
Are there any drug
interactions?
Certain medicines may interact with nettle. Refer to drug interactions for a list of those medicines.
References:1. Obertreis B, Giller K, Teucher T, et al. Antiphlogistic effects of
Urtica dioica folia extract in comparison to caffeic malic acid.
Arzneimittelforschung 1996;46:52–6.
2. Hirano T, Homma M, Oka K. Effects of stinging nettle root extracts and
their steroidal components on the Na+,K+-ATPase of the benign prostatic hyperplasia.
Planta Med 1994;60:30–3.
3. Vontobel H, Herzog R, Rutishauser G, Kres H. Results of a double-blind
study on the effectiveness of ERU (extractum radicis urticae) capsules in conservative
treatment of benign prostatic hyperplasia. Urologe 1985;24:49–51 [in
German].
4. Mittman P. Randomized, double-blind study of freeze-dried Urtica
dioica in the treatment of allergic rhinitis.Planta Med 1990;56:44–7.
5. Randall C, Meethan K, Randall H, Dobbs F. Nettle sting of Urtica
dioica for joint pain--an exploratory study of this complementary therapy. Compl Ther
Med 1999;7:126–31.
6. Brown D, Austin S, Reichert R. Benign Prostatic Hyperplasia and
Prostate Cancer Prevention. Seattle: NPRC, 1997, 9–10.
7. Blumenthal M, Busse WR, Goldberg A, et al. (eds). The Complete
Commission E Monographs: Therapeutic Guide to Herbal Medicines. Boston, MA: Integrative
Medicine Communications, 1998, 216–7.