Stinging Nettle

Galen and Dioscorides both recommended the leaf for asthma, pleurisy and conditions of the spleen, and noted its diuretic and laxative effects ^{36Reference 36Taylor · 2005The healing power of rainforest herbs: A guide to understanding and using herbal medicinals}.

Nettle was used historically as a diuretic, to build the blood, for arthritis and rheumatism, and on the scalp to improve the hair ^{36Reference 36Taylor · 2005The healing power of rainforest herbs: A guide to understanding and using herbal medicinals}. In Europe, especially Germany, it is used for rheumatic and other inflammatory conditions, prostate complaints, and as a diuretic ^{36Reference 36Taylor · 2005The healing power of rainforest herbs: A guide to understanding and using herbal medicinals}. Nursing mothers took the leaf to support their milk supply ^{35Reference 35Bhusal KK et al. · 2022ReviewNutritional and pharmacological importance of stinging nettle (Urtica dioica L.): a reviewView study →}.

Rubbing or striking the fresh leaf on an aching joint, so that the sting acts as a counter-irritant, is an old folk remedy for arthritis pain, and it was this practice that the first controlled nettle trial set out to test ^{25Reference 25Randall C et al. · 2000RCTRandomised controlled trial of nettle sting for treatment of base-of-thumb pain — randomised controlled crossover trialView study →}.

Early American herbalists used the leaf and stem as a wound dressing, infusing them and soaking the infusion into bandages ^{36Reference 36Taylor · 2005The healing power of rainforest herbs: A guide to understanding and using herbal medicinals}. Taken internally, the leaf was recommended as a nutritious food for its mineral content, in convalescence and in weight-reduction regimes ^{36Reference 36Taylor · 2005The healing power of rainforest herbs: A guide to understanding and using herbal medicinals}.

In current Western herbal practice the two parts are used differently. The leaf is given as a diuretic and for arthritis, prostatitis and allergies. The root is used mainly for benign prostatic hyperplasia and for hair loss ^{36Reference 36Taylor · 2005The healing power of rainforest herbs: A guide to understanding and using herbal medicinals}.

The European regulator recognises these as traditional uses. The leaf and herb are registered for minor urinary complaints, to increase the flow of urine alongside plenty of fluid, for minor joint pain and for seborrhoeic skin conditions ^{42Reference 42European Medicines Agency · 2025ReviewEuropean Union herbal monograph on Urtica dioica L.; Urtica urens L., herba, Revision 1 (EMA/HMPC/261302/2022) — regulatory monograph. https://www.ema.europa.eu/en/documents/herbal-monograph/final-european-union-herbal-monograph-urtica-dioica-l-urtica-urens-l-herba-revision-1_en.pdfView study →}. The root is registered for the urinary symptoms of benign prostatic hyperplasia once a doctor has ruled out serious disease ^{43Reference 43European Medicines Agency · 2025ReviewEuropean Union herbal monograph on Urtica dioica L.; Urtica urens L., radix, Revision 1 (EMA/HMPC/322646/2023) — regulatory monograph. https://www.ema.europa.eu/system/files/documents/herbal-monograph/urticae-radix-mo_en.pdfView study →}.

Nettle was also a fibre plant. The stems were retted and spun for textiles in place of flax or hemp, and nettle oil was burned for light in Egypt ^{38Reference 38Bone K · 2013Principles and Practice of Phytotherapy}.

In Brazil the whole plant was used for heavy menstrual bleeding, diarrhoea, diabetes, urinary disorders and respiratory complaints, and applied to the skin for a range of skin conditions ^{36Reference 36Taylor · 2005The healing power of rainforest herbs: A guide to understanding and using herbal medicinals}.

In Peru nettle is used for muscular pain, arthritis, ulcers, diabetes, digestive complaints, nosebleeds and rheumatism. It is also applied externally for inflammation and pain, and against head lice ^{36Reference 36Taylor · 2005The healing power of rainforest herbs: A guide to understanding and using herbal medicinals}.

The root is the part tested here. A 6-month, double-blind, partial-crossover RCT (n=620) reported 81% of root-extract patients improving on lower-urinary-tract symptoms against 16% on placebo ^{1Reference 1Safarinejad MR · 2005RCTUrtica dioica for treatment of benign prostatic hyperplasia: a prospective, randomised, double-blind, placebo-controlled crossover study — randomised controlled trialView study →}. IPSS fell from 19.8 to 11.8 on nettle against 19.2 to 17.7 on placebo, and peak flow and residual urine improved ^{1Reference 1Safarinejad MR · 2005RCTUrtica dioica for treatment of benign prostatic hyperplasia: a prospective, randomised, double-blind, placebo-controlled crossover study — randomised controlled trialView study →}.

In the same trial PSA and testosterone were unchanged, and prostate volume fell modestly, from 40.1 to 36.3 cc ^{1Reference 1Safarinejad MR · 2005RCTUrtica dioica for treatment of benign prostatic hyperplasia: a prospective, randomised, double-blind, placebo-controlled crossover study — randomised controlled trialView study →}. Ninety per cent of patients completed it, and both arms continued on nettle to 18 months ^{1Reference 1Safarinejad MR · 2005RCTUrtica dioica for treatment of benign prostatic hyperplasia: a prospective, randomised, double-blind, placebo-controlled crossover study — randomised controlled trialView study →}.

A German 12-month multicentre RCT of Bazoton-uno (459 mg root dry extract, n=246) found a smaller but significant IPSS advantage: 18.7 to 13.0 against 18.5 to 13.8 on placebo (p=0.023) ^{3Reference 3Schneider T · 2004RCTStinging nettle root extract (Bazoton-uno) in long-term treatment of benign prostatic syndrome — randomised, double-blind, placebo-controlled multicentre studyView study →}. Flow rate and residual volume did not differ from placebo ^{3Reference 3Schneider T · 2004RCTStinging nettle root extract (Bazoton-uno) in long-term treatment of benign prostatic syndrome — randomised, double-blind, placebo-controlled multicentre studyView study →}.

A 60-patient trial of 450 mg root extract daily for 12 weeks saw IPSS improvement alongside falls in hs-CRP and malondialdehyde ^{2Reference 2Karami AA et al. · 2020RCTUrtica dioica root extract on clinical and biochemical parameters in patients with benign prostatic hyperplasia — randomised controlled trialView study →}.

The proposed mechanism is root lignans and sterols competing for sex-hormone-binding globulin, based on older in-vitro binding work ^{35Reference 35Bhusal KK et al. · 2022ReviewNutritional and pharmacological importance of stinging nettle (Urtica dioica L.): a reviewView study →}. In a mouse BPH model, the root combined with saw palmetto reduced prostate weight, Ki-67 proliferation and CD45+ inflammatory infiltrate ^{10Reference 10Pigat N et al. · 2019AnimalCombined Sabal and Urtica extracts (WS 1541) exert anti-proliferative and anti-inflammatory effects in a mouse model of benign prostate hyperplasia — animal modelView study →}.

Most of the trial literature tests nettle root combined with saw palmetto (PRO 160/120, WS 1541) or pygeum. In those trials symptom and nocturia benefits matched finasteride or tamsulosin, but the combination hides nettle’s own contribution ^{5,6,7,8Reference 5Sökeland J · 2000RCTCombined sabal and urtica extract compared with finasteride in men with benign prostatic hyperplasia — randomised trialView study →Reference 6Lopatkin N et al. · 2007RCTEfficacy and safety of a combination of Sabal and Urtica extract in lower urinary tract symptoms — placebo-controlled, double-blind, multicentre trialView study →Reference 7Oelke M et al. · 2014RCTFixed-dose combination PRO 160/120 of sabal and urtica extracts improves nocturia in men with LUTS suggestive of BPH — re-evaluation of four randomised controlled trialsView study →Reference 8Krzeski T et al. · 1993RCTCombined extracts of Urtica dioica and Pygeum africanum in the treatment of benign prostatic hyperplasia — double-blind randomised comparison of two dosesView study →}. The most-cited meta-analysis found no convincing evidence for Urtica alone ^{4Reference 4Wilt TJ et al. · 2000Meta-analysisPhytotherapy for benign prostatic hyperplasia — systematic review/meta-analysisView study →}, and the same confound applies to ProstaMEV added to antibiotics in prostatitis ^{9Reference 9Cai T et al. · 2009RCTSerenoa repens with Urtica dioica (ProstaMEV) plus curcumin and quercetin improve the efficacy of prulifloxacin in bacterial prostatitis — prospective randomised studyView study →}.

Gap: The pivotal meta-analysis predates the largest single-herb trials, and no independent trial has tested root extract alone against a modern comparator drug.

Leaf extract lowers blood glucose in type 2 diabetes. A 2022 meta-analysis of 13 trials found significant reductions in fasting glucose (−17.2 mg/dL), HbA1c (−0.93%), CRP, triglycerides and systolic pressure, with insulin and LDL/HDL unchanged ^{11Reference 11Tabrizi R et al. · 2022Meta-analysisEffects of Urtica dioica on metabolic profiles in type 2 diabetes — systematic review and meta-analysis of clinical trialsView study →}.

An independent 2020 meta-analysis of 8 RCTs (401 participants) confirmed the fasting-glucose drop (−18.0 mg/dL) but found no change in HbA1c, insulin or insulin resistance, with very high heterogeneity ^{12Reference 12Ziaei R et al. · 2020Meta-analysisThe effect of nettle (Urtica dioica) supplementation on glycemic control in type 2 diabetes — systematic review and meta-analysisView study →}.

In a placebo-controlled trial in 92 patients with advanced type 2 diabetes needing insulin, 500 mg of leaf extract every 8 hours for three months, added to their usual oral drugs, lowered fasting glucose, post-meal glucose and HbA1c ^{13Reference 13Kianbakht S et al. · 2013RCTImproved glycemic control in patients with advanced type 2 diabetes taking Urtica dioica leaf extract — randomised double-blind placebo-controlled trialView study →}.

The trial’s authors base the rationale on earlier work describing the leaf as an insulin secretagogue, a PPAR-γ agonist and an α-glucosidase inhibitor ^{13Reference 13Kianbakht S et al. · 2013RCTImproved glycemic control in patients with advanced type 2 diabetes taking Urtica dioica leaf extract — randomised double-blind placebo-controlled trialView study →}. Some positive results come from multi-herb formulations, which dilute attribution ^{14Reference 14Khalili N et al. · 2017RCTSilymarin, olibanum and nettle, a mixed herbal formulation in type II diabetes — randomised, double-blind, placebo-controlled trialView study →}.

Gap: Trials are small, short, mostly Iranian and use non-standardized leaf preparations at varying doses; the fasting-glucose signal is consistent but the HbA1c effect is inconsistent, so durable glycemic benefit is unproven.

Across DPPH, ABTS, FRAP and CUPRAC assays, nettle extracts show substantial radical-scavenging and ferric-reducing power, from flavonoids (rutin, quercetin) and phenolic acids (chlorogenic acid) ^{15,16Reference 15Jaiswal V · 2022ReviewAntioxidant activity of Urtica dioica: an important property contributing to multiple biological activities — reviewView study →Reference 16Uğur Y · 2023In vitroDetermination of phytochemical content by LC-MS/MS, antioxidant capacity and enzyme inhibition effects of nettle (Urtica dioica) — in vitroView study →}.

In spontaneously hypertensive rats, leaf extract raised plasma antioxidant capacity, SOD and catalase while lowering systemic oxidative stress ^{22Reference 22Vajic UJ et al. · 2018AnimalUrtica dioica leaf extract modulates blood pressure and oxidative stress in spontaneously hypertensive rats — animal modelView study →}. A 2022 review catalogues organ-protective effects across brain, liver, lung, kidney and reproductive tissue ^{15Reference 15Jaiswal V · 2022ReviewAntioxidant activity of Urtica dioica: an important property contributing to multiple biological activities — reviewView study →}.

These assays measure chemistry in a tube rather than a clinical outcome. The only human signals are secondary endpoints inside the diabetes and BPH trials.

Nettle suppresses several inflammatory pathways. A standardised leaf extract (IDS23) blocks activation of the transcription factor NF-κB in several cell types. It works not by blocking NF-κB’s binding to DNA but by preventing the breakdown of its inhibitor, IκB-α ^{44Reference 44Riehemann K et al. · 1999In vitroPlant extracts from stinging nettle (Urtica dioica), an antirheumatic remedy, inhibit the proinflammatory transcription factor NF-kappaB — in vitroView study →}.

In human chondrocytes, the leaf extract Hox alpha (made from U. dioica and U. urens) and its constituent 13-HOTrE cut IL-1β-induced matrix metalloproteinase-1, -3 and -9, which break down joint cartilage ^{17Reference 17Schulze-Tanzil G et al. · 2002In vitroEffects of the antirheumatic remedy Hox alpha, a stinging nettle leaf extract, on matrix metalloproteinases in human chondrocytes — in vitroView study →}.

Aerial-part and root extracts selectively inhibit cyclooxygenase and lipoxygenase in human platelets, and root extract lowers LPS-induced chemokine release and COX-2 in intestinal cells ^{18Reference 18Francišković M et al. · 2017In vitroChemical composition and immuno-modulatory effects of Urtica dioica extracts — in vitroView study →}.

A 2026 study of nine preparations on primary human T-cells found nettle downregulates CD25/CD69, cuts interleukin-2 and suppresses NFAT-dependent transcription, with effect size differing markedly by extract ^{19Reference 19Wilmers A et al. · 2026In vitroComparative study of different stinging nettle preparations regarding their immunomodulating effect on primary human T-lymphocytes — in vitroView study →}.

In rodent colitis models, leaf extract (IDS 30) in mice and seed oil in rats reduced inflammatory cytokines (TNF-α, IL-1β, and IL-6 with the seed oil) and disease severity ^{20,21Reference 20Konrad A et al. · 2005AnimalAmeliorative effect of IDS 30, a stinging nettle leaf extract, on chronic colitis — mouse modelView study →Reference 21Genc Z et al. · 2011AnimalThe effect of stinging nettle (Urtica dioica) seed oil on experimental colitis in rats — animal modelView study →}.

Gap: The human evidence is all isolated cells and tissue; no controlled human trial has tested nettle against a defined inflammatory disease.

Nettle lowers blood pressure in animal models through a vascular mechanism. In spontaneously hypertensive rats, four weeks of leaf extract cut systolic and diastolic pressure and cardiac index at all three doses tested, with losartan as the comparison drug ^{22Reference 22Vajic UJ et al. · 2018AnimalUrtica dioica leaf extract modulates blood pressure and oxidative stress in spontaneously hypertensive rats — animal modelView study →}.

A later study in the same model showed anti-fibrotic kidney protection with raised eNOS ^{24Reference 24Vajic UJ et al. · 2024AnimalUrtica dioica leaf extract dose-dependently modulates oxidative stress in the kidney and exerts anti-fibrotic and anti-inflammatory properties in SHR — animal modelView study →}.

Work on isolated vessels attributes the effect to endothelium-dependent, nitric-oxide-mediated vasorelaxation plus calcium-channel blockade comparable to verapamil ^{23Reference 23Qayyum R et al. · 2016In vitroMechanisms underlying the antihypertensive properties of Urtica dioica — in vitro/in vivo animal studyView study →}.

The only human signal is the −5 mmHg systolic drop seen as a secondary outcome in the diabetes meta-analysis ^{11Reference 11Tabrizi R et al. · 2022Meta-analysisEffects of Urtica dioica on metabolic profiles in type 2 diabetes — systematic review and meta-analysis of clinical trialsView study →}.

Gap: No dedicated human hypertension trial exists; all direct blood-pressure data are from rats.

The evidence here is for the fresh leaf applied to the skin, not an oral preparation. A double-blind randomized crossover trial (n=27) applied fresh nettle leaf daily for a week to osteoarthritic pain at the base of the thumb or index finger, against white deadnettle as placebo, and found significantly greater reductions in pain and disability ^{25Reference 25Randall C et al. · 2000RCTRandomised controlled trial of nettle sting for treatment of base-of-thumb pain — randomised controlled crossover trialView study →}.

A later patient-blinded pilot in 42 people with knee osteoarthritis compared a week of the sting with a non-stinging nettle (Urtica galeopsifolia). It was designed to test feasibility, and pain fell by much the same amount in both groups ^{45Reference 45Randall C et al. · 2008RCTNettle sting for chronic knee pain: a randomised controlled pilot study — randomised controlled trialView study →}.

A small nettle-cream study ^{26Reference 26Rayburn K et al. · 2009Clinical trialStinging nettle cream for osteoarthritis — clinical trialView study →} and a 13-patient pilot of a five-herb oral blend with thiamine ^{27Reference 27Hedaya R · 2017Clinical trialFive herbs plus thiamine reduce pain and improve functional mobility in patients with pain — pilot studyView study →} also reported relief, though the latter cannot isolate nettle. The proposed mechanism is the leaf’s MMP- and cytokine-suppressing activity ^{17Reference 17Schulze-Tanzil G et al. · 2002In vitroEffects of the antirheumatic remedy Hox alpha, a stinging nettle leaf extract, on matrix metalloproteinases in human chondrocytes — in vitroView study →}.

Gap: The key trial is small (n=27) and tests the sting applied to the skin; the knee study was a feasibility pilot that found no difference, and the oral pilot is uncontrolled and combines five herbs.

Nettle extract inhibits the histamine-1 receptor, mast-cell tryptase, and COX-1, COX-2 and hematopoietic prostaglandin-D2 synthase in vitro, all part of the machinery of allergic inflammation ^{28Reference 28Roschek B Jr et al. · 2009In vitroNettle extract (Urtica dioica) affects key receptors and enzymes associated with allergic rhinitis — in vitroView study →}.

In a 1990 double-blind RCT of freeze-dried nettle (n=98), it was rated above placebo on global assessment but only slightly better on daily symptom diaries ^{29Reference 29Mittman P · 1990RCTRandomised, double-blind study of freeze-dried Urtica dioica in the treatment of allergic rhinitis — randomised controlled trialView study →}. A 2017 root-extract RCT (74 patients, 40 completing) found SNOT-22 improvement matched by an equally large placebo response, with no change in IgE or IL-4/IL-5 ^{30Reference 30Bakhshaee M et al. · 2017RCTEfficacy of supportive therapy of allergic rhinitis by stinging nettle (Urtica dioica) root extract — randomised, double-blind, placebo-controlled trialView study →}.

Gap: Both human trials are small and neither shows convincing separation from placebo.

Nettle protects the liver in chemical-injury animal models. In CCl4-challenged rats, the ethyl-acetate fraction of a whole-plant extract blunted the rise in serum liver enzymes and tissue oxidative markers and protected HepG2 cells, with ferulic acid isolated as the active constituent ^{31Reference 31Joshi BC et al. · 2015In vitroHepatoprotective potential of antioxidant-potent fraction from Urtica dioica (whole plant) in CCl4-challenged rats — in vitro and animal modelView study →}.

Related work reports protection against aflatoxin- and cisplatin-induced damage ^{15Reference 15Jaiswal V · 2022ReviewAntioxidant activity of Urtica dioica: an important property contributing to multiple biological activities — reviewView study →}.

Gap: All of it is cells or rodents exposed to a chemical toxin; there are no human data.

Topical nettle speeds wound closure in animals. A full-thickness rat study found an extract ointment healed wounds in 9 days against 13 for controls ^{32Reference 32Kasouni AI et al. · 2021In vitroThe unexplored wound-healing activity of Urtica dioica extract — in vitro and in vivo (rat) studyView study →}.

A second study, of a leaf extract, reported 92% closure by day 11 against 61%, and linked the effect to the triterpene lupeol and the leaf’s polyphenols ^{33Reference 33Zouari Bouassida K et al. · 2017AnimalExploring the Urtica dioica leaves hemostatic and wound-healing potential — animal modelView study →}.

Both are rodent studies, with no human trial.

In a comparative in-vitro screen against finasteride, Urtica dioica extracts inhibited 5α-reductase, the enzyme that converts testosterone to dihydrotestosterone ^{34Reference 34Nahata A · 2014In vitroEvaluation of 5α-reductase inhibitory activity of certain herbs useful as antiandrogens — in vitroView study →}. This matches the antiandrogen mechanisms proposed for the prostate use. No human or animal hair-growth study has tested it.

Gap: Support rests entirely on a single in-vitro enzyme assay plus traditional use; there are no clinical or even animal hair-growth data.

Tolerability. In prostate trials of up to 18 months, side effects were mild, infrequent and similar to placebo ^{1,3Reference 1Safarinejad MR · 2005RCTUrtica dioica for treatment of benign prostatic hyperplasia: a prospective, randomised, double-blind, placebo-controlled crossover study — randomised controlled trialView study →Reference 3Schneider T · 2004RCTStinging nettle root extract (Bazoton-uno) in long-term treatment of benign prostatic syndrome — randomised, double-blind, placebo-controlled multicentre studyView study →}. The diabetes trial of leaf extract reported no significant effect on kidney or liver markers ^{13Reference 13Kianbakht S et al. · 2013RCTImproved glycemic control in patients with advanced type 2 diabetes taking Urtica dioica leaf extract — randomised double-blind placebo-controlled trialView study →}.

Reported side effects. The EU monographs list nausea, vomiting and diarrhoea for the herb, and nausea, heartburn, fullness, wind and diarrhoea for the root, along with allergic itching, rash and hives, all of unknown frequency ^{42,43Reference 42European Medicines Agency · 2025ReviewEuropean Union herbal monograph on Urtica dioica L.; Urtica urens L., herba, Revision 1 (EMA/HMPC/261302/2022) — regulatory monograph. https://www.ema.europa.eu/en/documents/herbal-monograph/final-european-union-herbal-monograph-urtica-dioica-l-urtica-urens-l-herba-revision-1_en.pdfView study →Reference 43European Medicines Agency · 2025ReviewEuropean Union herbal monograph on Urtica dioica L.; Urtica urens L., radix, Revision 1 (EMA/HMPC/322646/2023) — regulatory monograph. https://www.ema.europa.eu/system/files/documents/herbal-monograph/urticae-radix-mo_en.pdfView study →}.

The sting. The stinging hairs of the fresh leaf inject formic acid, histamine, serotonin and acetylcholine, which cause a brief nettle rash. Allergic reactions to nettle pollen are rare.

Skin contact in infants. A 17-day-old baby developed hives all over the body after the mother put water boiled with nettle on her cracked nipples before and after feeds. The baby had raised nettle-specific IgE, and the rash cleared within two days ^{46Reference 46Uslu S et al. · 2011Case reportUrticaria due to Urtica dioica in a neonate — case reportView study →}.

Blood sugar and blood pressure. Leaf extract lowers blood glucose in people with type 2 diabetes and blood pressure in rats, so it may add to the effect of antidiabetic and antihypertensive drugs ^{11,12,22Reference 11Tabrizi R et al. · 2022Meta-analysisEffects of Urtica dioica on metabolic profiles in type 2 diabetes — systematic review and meta-analysis of clinical trialsView study →Reference 12Ziaei R et al. · 2020Meta-analysisThe effect of nettle (Urtica dioica) supplementation on glycemic control in type 2 diabetes — systematic review and meta-analysisView study →Reference 22Vajic UJ et al. · 2018AnimalUrtica dioica leaf extract modulates blood pressure and oxidative stress in spontaneously hypertensive rats — animal modelView study →}. This is inferred from efficacy trials and animal work; no interaction study has been done.

Diuretics and fluid intake. Nettle leaf is a traditional diuretic, and could in theory add to diuretic medicines. The EU herb monograph does not recommend it for people who have been told to limit their fluid intake ^{42Reference 42European Medicines Agency · 2025ReviewEuropean Union herbal monograph on Urtica dioica L.; Urtica urens L., herba, Revision 1 (EMA/HMPC/261302/2022) — regulatory monograph. https://www.ema.europa.eu/en/documents/herbal-monograph/final-european-union-herbal-monograph-urtica-dioica-l-urtica-urens-l-herba-revision-1_en.pdfView study →}.

Warfarin. Nettle leaf contains vitamin K ^{35Reference 35Bhusal KK et al. · 2022ReviewNutritional and pharmacological importance of stinging nettle (Urtica dioica L.): a reviewView study →}. Its effect alongside warfarin has not been studied.

Drug metabolism. No pharmacokinetic or cytochrome P450 study of nettle has been published, and both EU monographs report no interactions ^{42,43Reference 42European Medicines Agency · 2025ReviewEuropean Union herbal monograph on Urtica dioica L.; Urtica urens L., herba, Revision 1 (EMA/HMPC/261302/2022) — regulatory monograph. https://www.ema.europa.eu/en/documents/herbal-monograph/final-european-union-herbal-monograph-urtica-dioica-l-urtica-urens-l-herba-revision-1_en.pdfView study →Reference 43European Medicines Agency · 2025ReviewEuropean Union herbal monograph on Urtica dioica L.; Urtica urens L., radix, Revision 1 (EMA/HMPC/322646/2023) — regulatory monograph. https://www.ema.europa.eu/system/files/documents/herbal-monograph/urticae-radix-mo_en.pdfView study →}. The cautions above are about what nettle does in the body, not about how drugs are cleared.

Hormonal effects. A 30-year-old woman developed breast discharge (galactorrhoea) after a month of 500 mg nettle a day for allergies. It cleared a week after she stopped. She was also using a contraceptive implant, so the link is uncertain ^{47Reference 47Easton L et al. · 2021Case reportStinging Nettle (Urtica dioica): An Unusual Case of Galactorrhea — case reportView study →}.

Children. The EU monographs do not recommend the herb for children under 12, or under 18 as a tea for urinary complaints or for joint pain, and give no use of the root under 18 ^{42,43Reference 42European Medicines Agency · 2025ReviewEuropean Union herbal monograph on Urtica dioica L.; Urtica urens L., herba, Revision 1 (EMA/HMPC/261302/2022) — regulatory monograph. https://www.ema.europa.eu/en/documents/herbal-monograph/final-european-union-herbal-monograph-urtica-dioica-l-urtica-urens-l-herba-revision-1_en.pdfView study →Reference 43European Medicines Agency · 2025ReviewEuropean Union herbal monograph on Urtica dioica L.; Urtica urens L., radix, Revision 1 (EMA/HMPC/322646/2023) — regulatory monograph. https://www.ema.europa.eu/system/files/documents/herbal-monograph/urticae-radix-mo_en.pdfView study →}.