Urtica dioica is a perennial plant growing almost throughout the world, where it has been used for thousands of years as food for animals and humans, raw material for string and rope, clothing, cosmetics and a variety of pharmaceutical applications. The stinging nettle’s main active components are formic acid, principally responsible for the stinging sensation, acetylcholine, histamine, glucoquinones, 5-hydroxytryptamine, chlorophyll, flavonoids including quercetin, amines, vitamins A, C, B2 and B5, and the minerals iron, magnesium, potassium, silica and sulfur.
- Anti-allergic. Nettles have been long used against sinus congestion and sinusitis, and a recent clinical trial has shown the usefulness of the plant in the treatment of allergic rhinitis and hayfever. This may be partly due to the anti-inflammatory effect detailed immediately below, and partly to the fact that the plant is a rich source of quercetin, which is known to inhibit the release of histamine.
- Anti-inflammatory. Relatively recent studies show that nettles and nettle extract inhibit the formation of series 1 prostaglandins and leucotrienes, thus substantially reducing inflammation. Nettles have been successfully used both internally and externally to treat eczema.
- Diuretic. A preparation made out of the leaves or the extracted juice has been shown to mobilize uric acid from the joints and its elimination through the kidneys, reducing the effects of gout and other conditions such as arthritis, lumbago, sciatica, tendonitis, etc. Other studies suggest that the general ability of nettles to increase urinary flow is accompanied by a relaxing effect on the urinary tract.
- Hair and skin tonic. Nettles have been traditionally used as an important hair and skin tonic. This is especially due to the high quantity of bioavailable silica in the plant, a useful element for stimulating the growth of hair, improving the condition of both hair and skin, and reducing dandruff.
- Hemostatic. Nettles have been also traditionally used as an astringent and styptic agent, to control excessive bleeding, wound healing and profuse menstruation.
- Nutritive. With their rich nutritional content, nettles have been traditionally fed to anemic, weak, exhausted, debilitated or recuperating people in the form of soups or teas. Often they have been eaten, since the stinging property is eliminated by boiling or cooking. During World War II, many persons were virtually saved from starvation by eating nettles.