Written by: Ekatrina Barrett (2015)
Editor: Raffael Dudler (Dudler Herbal (July 2016).
(We acknowledge and thank Lincoln College for their support in sharing this monograph for educational purposes).
Urtica dioica is a common herbaceous perennial of the family Urticaceae that can grow up to 2m tall.
Its leaves are simple, soft and serrated and arranged with two leaves per node on the stem that are opposite. The leaves and stem of the plant are coated in hairs, some of which are specialized to sting. When flowering, Urtica dioica has small, greenish-white flowers with four petals arranged in dense clusters. There are five subspecies of Urtica dioica (Kew, 2015).
Common stinging nettle, great nettle, stinger, stinging nettle (RHS, 2015), Dwarf nettle, nettle. (Medicines Complete, 2015)
Parts used: Leaf, root. (Bone and Mills, 2013)
Dosage: Nettle can be used topically or internally, as a liquid or in solid form, with no restriction on long term use (Bone and Mills, 2013).
Soaking the plant in water (Tilford, 1997), cooking, drying or even crushing will remove the sting from the plant, allowing it to be handled and ingested safely (Stewart, G. 2015).
Nettle is used in soups and herbal teas (Medicines Complete, 2015), and has been listed previously in the USA as a herb of undefined safety (Duke, 1985).
Nettle leaf contains flavonols glycosides (such as rutin) (Chaurasia and Wichtl, 1987), sterols, (Chaurasia and Wichtl, 1987) the coumarin scopoletin (from flowers), chlorophyll, vitamins (such as C, B, K) (Bone and Mills, 2013) and minerals (such as calcium, potassium and silicon).
It also has carotenoids and a variety of acids (such as caffeic, citric, fumaric, etc.) (Bakke et al., 1978). The stinging hairs of nettle contain amines including histamine and serotonin (Adamski and Bieganska, 1984).
Nettle root has sterols, steryl glycosides, polyphenols, polysaccharides and phenylpropanes, as well as scopoletin (Bone and Mills, 2013). Lignans (Schöttner, 1997), linked with Nettle’s benign prostatic hyperplasia activity (Bone and Mills, 2013), are also found in nettle root.
Nettle has been used traditionally both internally and externally. Externally, nettle’s sting has been used therapeutically in the past for arthritic conditions. The sting, when applied to a painful joint, would bring blood to the surface and help to expel accumulated toxins in the area in this way, sometimes in the form of a blister (MDidea, 2015). Other external uses included nettle leaf being used topically in burns, wounds, nosebleeds and inflammation of the mouth and throat (Bone and Mills, 2013).
Internally, Nettle leaf or root would be taken for bronchial and asthmatic conditions, chronic colon diseases, skin rashes and chronic skin eruptions such as eczema (Bone and Mills, 2013). Greek physicians reported that Nettle was a diuretic and a laxative, and was indicated in asthma, pleurisy and skin illnesses (MDidea, 2015). Austrian traditional medicine used nettle’s diuretic properties in treating kidney and urinary tract disorders (Vogl et al., 2013) Nettle was also known to be nourishing, which is backed up by modern-day studies showing that it is high in vitamins and minerals such as iron and vitamin C (which is very helpful for patients in debilitated states or with anemia) (MDidea, 2015).
Benign Prostate Hyperplasia (BHP)
9-hydroxy-10-trans-12-cis-octadecadienic acid (HOA) is a compound in nettle root that has been found to inhibit aromatase in the prostate, an enzyme that converts testosterone into oestrogen and is naturally higher in older males, and is linked to prostate enlargement and disease (Kraus et al., 1991). Additionally, nettle extract was found to affect the zinc and calcium levels in the tissue of BHP patients, which may alter the zinc-testosterone metabolism and lower zinc secretion in the prostate (Romics and Bach, 1991).
Clinical trials have successfully provided evidence for the efficacy of Urtica dioica as a supportive treatment in BHP patients. One example is a double-blind, randomised clinical study found that treatment with Urtica dioica compared to placebo increased urinary flow and relief of urinary symptoms in patients with BHP, as well as a decrease in prostate enlargement (Safarinejad, 2005). The effects of treatment were maintained at the 18 month follow up.
In vitro trials with whole human blood have suggested that nettle leaf extract has the potential to inhibit the inflammatory cascade in autoimmune conditions such as rheumatoid arthritis (Klingelhoefer et al., 1999). There has been a series of reports of individuals successfully using nettle leaf as a counter-irritant in osteoarthritis, which led to further investigation. (Randall et al., 1999)
The study this prompted was a randomised, double-blind and controlled study of 27 patients using nettle leaf against placebo on osteoarthritic pain at the base of the thumb. (Randall et al., 2000) Patients with nettle reported a greater reduction in pain and disability than those using the placebo.
An open and uncontrolled study of nettle use in patients with myocardial or chronic venous insufficiency reported that nettle had diuretic properties (ESCOP, 1999). Patients reported increased urinary flow, possibly due to the presence of potassium in aqueous extracts of nettle. (Szentmihályi, 1998) The use of nettle as part of a treatment in lower urinary tract infections and to prevent the formation of urinary gravel has been approved by the German Commission E (Blumenthal et al., 1998), and another open label study following 114 patients found increased urinary flow, a decrease in urinary pain and dysuria (Bone and Mills, 2013). However, this study was conducted without a placebo group. Additionally, care should be taken when administering nettle for certain urinary conditions such as interstitial cystitis, as patients with this condition are sensitive to potassium, and increased potassium from nettle could aggravate their condition (Lowell Parsons, 2002).
People with an allergy to nettle stings should not apply or take internally fresh nettle leaves (Bone and Mills, 2013) .Care to be taken with administering to individuals sensitive to potassium in urine (e.g interstitial cystitis) (Lowell Parsons, 2002).
Adamski, R. and Bieganska, J. (1984) Studies on substances present in Urtica dioica L. leaves II. Analysis for protein amino acids and nitrogen containing non-protein amino acids, Herba Pol, (30), pp. 17–26.
Bach, D. and Romics, I. (1991) Zn, Ca and Na levels in the prostatic secretion of patients with prostaticadenoma, International Urology and Nephrology, 23(1) pp. 45–49.
Bakke, I.L.F. et al.(1978) Water-soluble acids from Urtica dioica L. Medd Nor Farm Selsk, (40), pp. 181–188.
Blumenthal, M., Busse, W.R., Goldberg, A., et al. (1998) The Complete German Commission E Monographs: Therapeutic Guide to Herbal Medicines. Austin, TX, American Botanical Council, p. 216.
Bone, K. and Mills, S. (2013) Principles and Practice of Phytotherapy: Modern Herbal Medicine, 2nd edition, London, Churchill Livingstone.
Chaurasia, N. and Wichtl, M. (1987) Sterols and steryl glycosides from Urtica dioica, J Nat Prod, (50), pp. 881–885.
Chaurasia, N., and Wichtl, M. (1987) Flavonolglykoside aus Urtica dioica, Planta Med, (53), pp. 432–434.
Duke, J.A. (1985) Handbook of Medicinal Herbs, Boca Raton, CRC
ESCOP (1999) Monographs on the Medicinal Uses of Plant Drugs, Fascicules 1 and 2 (1996), Fascicules 3, 4 and 5 (1997), Fascicule 6 (1999). Exeter: European Scientific Cooperative on Phytotherapy.
Kew (Royal Botanical Gardens) (2015) Urtica dioica (nettle) [on line] Available from http://www.kew.org/science-conservation/plants-fungi/urtica-dioica-nettle [acessed 3rd November 2015].
Klingelhoefer S et al. (1999) Antirheumatic effect of IDS 23, a stinging nettle leaf extract, on in vivo expression of T helper cytokines, J Rheumatol , (26), pp. 2517–2522.
Kraus, R., Spitelleer, G. and Bartsch, W. (1991) (10-E, 12Z)-9-hydroxy-10,12-octadecadienic acid, an aromatase-inhibiting substance from the root extract of Urtica dioica, Liebigs Ann Chem, (19), pp. 335-339.
Lowell Parsons, C. (2002) Interstitial Cystitis and Lower Urinary Tract Symptoms in Males and Females—The Combined Role of Potassium and Epithelial Dysfunction, Rev Urol. 4(Suppl 1) S49–S55.
MDidea Extracts Professional (2015) Historical and traditional use of Nettle [on line] Available from: http://www.mdidea.com/products/new/new00905.html [Accessed 10 Nov 15]
Medicines Complete (2015) Nettle [on line] Available from https://www.medicinescomplete.com/mc/herbals/current/HBL1000735873.htm?q=urtica%20dioica&t=search&ss=text&p=1#HBL1000727556 [Accessed 4 November 2015].
Randall, C., Meethan, K., Randall, H. and Dobbs, F. (1999) Nettle sting of Urtica dioica for joint pain–an exploratory study of this complementary therapy. Complement Ther Med., 7(3) pp. 126-31.
Randall, C., Randall, H., Dobbs, F., Hutton, C. and Sanders, H. (2000) Randomized controlled trial of nettle sting for treatment of base-of-thumb pain, J R Soc Med., (6), pp. 305-9.
Royal Horticultural Society (2015) Urtica dioica [on line] Available from https://www.rhs.org.uk/Plants/18618/i-Urtica-dioica-i/Details [Accessed 3rd November 2015].
Safarinejad, M.R. (2005) Urtica dioica for treatment of benign prostatic hyperplasia: prospective, randomized, double-blind, placebo-controlled, crossover study, J Herb Pharmacother, (5) pp. 1-11.
Schöttner, M., Gansser, D. and Spiteller, G. (1997) Lignans from the roots of Urtica dioica and their metabolites bind to human sex hormone binding globulin (SHBG), Planta Med. 63(6) pp. 529-32.
Stewart, G. (2015) How to harvest, dry, freeze and use stinging nettle [on line] Available from http://www.gettystewart.com/how-to-harvest-dry-freeze-use-stinging-nettle/ [Accessed 4 November 2015].
Szentmihályi, K. et al. (1998) Potassium-sodium ratio for the characterization of medicinal plants extracts with diuretic activity, Phytother Res., (12), pp. 163–166.
Tilford, G.L. (1997) Edible and Medicinal Plants of the West, Missoula, Mountain Press.
Vogl, S., Picker, P., Mihaly-Bison, J., Fakhrudin, N., Atanasov, A,G,., Heiss, E,H,., Wawrosch, C., Reznicek, G., Dirsch, V.M., Saukel, J. and Kopp, B. (2013) Ethnopharmacological in vitro studies on Austria’s folk medicine – An unexplored lore in vitro anti-inflammatory activities of 71 Austrian traditional herbal drugs, J Ethnopharmacol, (149), pp. 750–71.