Nettles

Stinging nettle (Urtica dioica) is a perennial herb in the family Urticaceae, easily recognised by the burning sting that follows even a light brush against its young leaves. The aerial parts and the root are used in different ways and have different traditions of use. The European Medicines Agency Committee on Herbal Medicinal Products (EMA HMPCEuropean Medicines Agency, Committee on Herbal Medicinal Products (HMPC)) lists the leaf (Urticae folium) as a traditional herbal medicinal product for the supportive treatment of rheumatic complaints and for minor urinary complaints, and separately lists the root (Urticae radix) as a herbal medicinal product for the relief of lower urinary tract symptoms related to benign prostatic hyperplasia in men where serious conditions have been ruled out by a doctor.

In Austria, the Brennnessel grows along almost every garden edge, hedgerow, and forest path. The young spring leaves are the heart of the traditional Frühjahrskur, eaten as Brennnessel-Suppe, in spinach-style side dishes, or steeped as a daily spring tea over a few weeks. The leaf is rich in chlorophyll, flavonoids, and minerals including iron, calcium, and magnesium, along with notable amounts of silica. The root has a different chemical profile, with lectins and polysaccharides standing out in the research literature. Both Commission E and the EMA HMPCEuropean Medicines Agency, Committee on Herbal Medicinal Products (HMPC) have positive monographs on Urtica preparations.

Nettle has a long European history as both food and medicine. Dioscorides and Pliny mentioned it in the first century; the medieval herbals of Hildegard von Bingen and others described it for spring cleansing, for joint pain, and for urinary complaints. In folk medicine across Europe and the British Isles, fresh nettle stings were also applied directly to painful joints in a practice known as urtication or nettle-stinging, a counter-irritant tradition recorded from antiquity through the nineteenth century.

In the Austrian and southern German Bauerngarten tradition, nettle was rarely planted on purpose because it arrived on its own, and yet it was harvested every spring as one of the first green herbs of the year. The Frühjahrskur, a several-week ritual of drinking nettle tea or eating young nettles, runs through cookbooks and herbalist writing from the nineteenth century onwards. The European Medicines Agency Committee on Herbal Medicinal Products (EMA HMPCEuropean Medicines Agency, Committee on Herbal Medicinal Products (HMPC)) and the German Commission E both list separate monographs for the leaf and the root, reflecting the long-established split between supportive use of the leaf (rheumatic and urinary) and the more clinical context for root preparations (lower urinary tract complaints in men).

The leaf and the root carry different active constituents. The young leaf is rich in chlorophyll, flavonoids (notably quercetin and kaempferol glycosides), carotenoids, and minerals including iron, calcium, magnesium, and a notable silica content. The stinging hairs of the fresh plant carry formic acid, histamine, serotonin, and acetylcholine, which together produce the characteristic burning sting and which are inactivated by blanching, drying, or chopping. The root contains a different set of compounds, with lectins (the Urtica dioica agglutinin family), polysaccharides, and sterols standing out in pharmacognosy texts.

Mechanistic work on the root has investigated binding to sex hormone-binding globulin (SHBG) and modulation of aromatase and 5-alpha-reductase in laboratory work, mechanisms proposed to explain the modest improvements in lower urinary tract symptoms reported in clinical trials of root extracts. These are mechanistic hypotheses, not proven causal pathways, and they apply to standardised root extracts at specific doses studied as medicines. For the leaf, the working hypothesis is simpler: a mineral- and flavonoid-rich infusion that supports normal hydration and a gentle, traditional spring diet. As with many traditional herbs, the felt effect of a daily cup of nettle tea probably has as much to do with the warmth, the ritual, and the diet shift of a Frühjahrskur as with isolated chemistry.

Modern research on nettle splits cleanly between the leaf and the root. Leaf preparations have been studied for supportive use in rheumatic complaints and as a mild diuretic for minor urinary support, framings carried forward by the EMA HMPCEuropean Medicines Agency, Committee on Herbal Medicinal Products (HMPC) traditional-use monograph. A small trial published by Roschek and colleagues in 2009 looked at a freeze-dried nettle leaf extract in adults with seasonal allergic rhinitis and reported a modest improvement in symptoms over the study period, an interesting signal that has not yet been confirmed in larger trials.

Root preparations are studied in a different context, as a herbal medicinal product for lower urinary tract symptoms related to benign prostatic hyperplasia in men. Lopatkin and colleagues published a 2007 randomised controlled trial of a standardised nettle root extract that reported a modest improvement in symptom scores over a placebo-treated group. This is medicinal-product territory and is not a claim that applies to nettle as a food supplement: the EMA HMPCEuropean Medicines Agency, Committee on Herbal Medicinal Products (HMPC) monograph for the root is a traditional-use monograph (EMA/HMPC/322646/2023 Rev.1, adopted 22 January 2025), and well-established use was explicitly not granted because the placebo-controlled trials were judged inadequate. The leaf and the root are best understood as two distinct preparations with two distinct evidence bases.

Forms and preparation

For tea, place one to two teaspoons of dried nettle leaf (or a handful of young spring leaves) in a cup and pour over freshly boiled water. Steep for ten to fifteen minutes and strain before drinking. Wear gloves when harvesting the fresh plant; the sting fades within a few minutes once the leaves are blanched in boiling water or chopped finely. The youngest tips harvested in early spring before flowering have the best flavour and the most concentrated greens, minerals, and flavonoids. In the kitchen, young nettle leaves are used very much like spinach. Blanch the leaves for a minute in salted boiling water to deactivate the sting, drain, and use them in soup (Brennnessel-Suppe is the classic Austrian preparation), in dumpling fillings, in pasta, or chopped through risotto. For root preparations, follow the dose on the package; root extracts are a separate category, prepared from the autumn root and most often used as a standardised tincture or capsule rather than a home tea.

Dosage

As a leaf tea, two to four cups per day is the traditional range, often taken across several weeks as a spring cure. For culinary use, young nettles eaten as a vegetable have no particular daily limit and slot into a normal vegetable rotation through early spring. For root extracts, follow the package dose; clinical trials of standardised root extracts for lower urinary tract symptoms have used specific products at specific doses, and those do not transfer cleanly to home preparations. Build slowly. If you are new to nettle tea, try a single cup in the morning for a few days and see how you feel before stepping up to two or three cups daily. The diuretic effect is gentle but real, so drink water alongside, especially on warmer days. The spring cure is typically run for four to six weeks in March and April, then paused.