Stinging Nettle
Summary
Nettle root extract modestly eased urinary symptoms from an enlarged prostate in a 12-month placebo-controlled trial (grade C), and the EU recognizes it as a traditional herbal medicine for this use. Meta-analyses link nettle leaf to lower fasting glucose in type 2 diabetes (grade C) with very mixed results. Allergy and joint-pain evidence is small and inconsistent.
Key facts
- A perennial plant; the root and the leaf are used as different products[1]
- Prostate urinary symptoms (C), fasting glucose in type 2 diabetes (C), allergic rhinitis (D), thumb-joint pain with the fresh sting (D)[3][5][7][8][9]
- EU traditional herbal medicine (root) for lower urinary tract symptoms of benign prostatic hyperplasia after a doctor rules out serious conditions[1]
- EU monograph: for example 460 mg/day of one dry extract, or 2 g of cut root as tea 2–3 times daily[1]
- In the 12-month trial, symptom scores improved more than placebo but urine flow did not[3]
- Nausea, heartburn, fullness, flatulence, diarrhea and allergic skin reactions (frequency not known)[1]
- None reported in the EU monograph[1]
- 8 graded human outcomes on this page
- October 10, 2026
How it works
ProposedProposed actions of the root include anti-inflammatory and anti-proliferative effects on prostate tissue, and leaf preparations may act on insulin secretion and glucose uptake; none is established in people, and a review found the suggested prostate mechanisms undocumented.[3][6][10]
What the human research says
Human trials only, one row per outcome. The form column shows what each trial actually tested. Grades follow our evidence-grading policy.
At a glance: strongest evidence per outcome
| Outcome | Grade | Effect | Strongest evidence | Rows |
|---|---|---|---|---|
| Blood sugar | Grade C | Improved | Meta-analysis of 8 trials · n = 401 · 2020 | 2 rows |
| Prostate | Grade C | Improved | RCT · n = 257 · 2005 | 2 rows |
| Allergies | Grade D | Mixed | RCT · n = 98 · 1990 | 2 rows |
| Menopause | Grade D | Improved | RCT · n = 72 · 2019 | 1 row |
| Joint pain | Grade D | Improved | Crossover RCT · n = 27 · 2000 | 1 row |
Every graded row
| Outcome | Effect | Grade | Best evidence | PMID |
|---|---|---|---|---|
| Blood sugar in type 2 diabetes | Improved | Grade C | Meta-analysis · n = 401 · 2020 Adults with type 2 diabetes in 8 RCTs Form: Nettle preparations (mostly leaf) · Dose: Varied across trials · Duration: Varied across trials Fasting glucose fell 18 mg/dL versus control, with very high heterogeneity (I² 95%); insulin, insulin resistance and HbA1c did not change significantly. | 31802554 (opens PubMed)Source [11] |
| Prostate urinary symptoms with a saw palmetto and nettle root combination | Improved | Grade C | RCT · n = 257 · 2005 Older men with lower urinary tract symptoms from benign prostatic hyperplasia Form: Saw palmetto extract 160 mg + nettle root extract 120 mg per capsule (PRO 160/120) · Dose: 2 capsules a day · Duration: 24 weeks double-blind, then 24 weeks open-label IPSS fell 6 points with the combination versus 4 with placebo (p = 0.003, one-tailed); tolerability was similar to placebo. | 15928959 (opens PubMed)Source [2] |
| Prostate urinary symptoms (IPSS) over 12 months | Improved | Grade C | RCT · n = 246 · 2004 Men with benign prostatic syndrome Form: Nettle root dry extract (Bazoton uno) · Dose: 459 mg/day of dry extract · Duration: 12 months IPSS fell from 18.7 to 13.0 with nettle root versus 18.5 to 13.8 with placebo (p = 0.023). Peak urine flow and leftover urine changed similarly in both groups. Fewer adverse events and urinary infections on nettle root. | 15045190 (opens PubMed)Source [3] |
| Allergic rhinitis symptoms | Mixed | Grade D | RCT · n = 98 · 1990 Adults with allergic rhinitis Form: Freeze-dried nettle leaf · Dose: Not stated in the abstract · Duration: 1 week Nettle was rated higher than placebo in global assessments but only slightly higher in symptom diaries; 69 of 98 completed. | 2192379 (opens PubMed)Source [7] |
| Blood sugar in advanced type 2 diabetes | Improved | Grade D | RCT · n = 92 · 2013 Adults with type 2 diabetes needing insulin, on oral diabetes drugs Form: Nettle leaf extract · Dose: 500 mg every 8 hours · Duration: 3 months Fasting glucose, 2-hour post-meal glucose and HbA1c fell versus placebo, with no change in kidney or liver tests or blood pressure. | 24273930 (opens PubMed)Source [10] |
| Allergic rhinitis symptoms and markers | No effect | Grade D | RCT · n = 74 · 2017 Adults with allergic rhinitis and a positive skin prick test Form: Nettle root extract tablet (Urtidin) · Dose: 150 mg · Duration: 1 month Symptom scores improved in both the nettle and placebo groups; nasal eosinophils fell with nettle, IgE, IL-4 and IL-5 did not change. Only 40 of 74 completed. | 29844782 (opens PubMed)Source [8] |
| Menopausal hot flashes | Improved | Grade D | RCT · n = 72 · 2019 Postmenopausal women with at least 20 hot flashes a week Form: Nettle capsules · Dose: 450 mg/day · Duration: 7 weeks plus 4 weeks follow-up Hot-flash and quality-of-life scores improved more with nettle than with placebo plus sham acupuncture, similar to acupuncture; combining both added nothing. | 31126551 (opens PubMed)Source [12] |
| Base-of-thumb osteoarthritis pain (fresh leaf sting) | Improved | Grade D | Crossover RCT · n = 27 · 2000 Adults with osteoarthritic pain at the base of the thumb or index finger Form: Fresh stinging nettle leaf applied to the skin · Dose: Daily application to the painful area · Duration: 1 week per arm, 5-week washout Pain and disability scores fell more after nettle sting than after the placebo (white deadnettle leaf). | 10911825 (opens PubMed)Source [9] |
Forms
| Form | Elemental % | Absorption (human data) | GI tolerance | Studied for |
|---|---|---|---|---|
| Nettle root dry extract | Varies[1][3] | No human absorption data in our sources.[1] | Nausea, heartburn, fullness, flatulence, diarrhea and allergic skin reactions are listed; fewer adverse events than placebo in a 12-month trial.[1][3] | Prostate urinary symptoms (about 460 mg/day) |
| Cut nettle root as tea | Varies[1] | No human absorption data in our sources.[1] | Same listed side effects as other root preparations.[1] | EU traditional use: 2 g in 150 mL water, 2–3 times daily |
| Nettle leaf extract | Varies[5][10] | No human absorption data in our sources.[10] | No change in kidney or liver tests over 3 months at 1,500 mg/day.[10] | Blood sugar in type 2 diabetes |
| Saw palmetto + nettle root combination (PRO 160/120) | Varies[2] | No human absorption data in our sources.[2] | Tolerability comparable to placebo over 24 weeks.[2] | Prostate urinary symptoms |
Studied doses
Doses studied in human trials ranged from 450 to 1,500 mg/day of nettle extract: about 460 mg/day of root extract for 12 months for prostate symptoms, and 1,500 mg/day of leaf extract for 3 months in type 2 diabetes. Allergy trials ran 1 to 4 weeks.[3][10][12][7]
Interactions
Published interactions only: each row cites a source. No row means none was found in our sources, not that a combination is safe.
None found in our sources.
Who should be careful
- Prostate symptoms not yet checked by a doctor
- The EU indication applies only after serious conditions have been ruled out; see a doctor if fever, spasms, blood in the urine, painful urination or urinary retention occur.[1]
- Nettle allergy
- Hypersensitivity to nettle is the listed contraindication, and allergic skin reactions can occur.[1]
- People on glucose-lowering medicines
- Nettle leaf lowered fasting glucose in diabetes trials, including in people on oral diabetes drugs, so glucose may drop further.[5][10]
- Pregnancy, breastfeeding and children
- The EU monograph covers adult men only and lists no fertility, reproductive-toxicity or genotoxicity testing.[1]
Talk to your pharmacist or clinician before starting a supplement, especially if you take prescription medicines.
Safety
Generally well tolerated in trials up to 12 months.
- Gut and skin effects
- Nausea, heartburn, fullness, flatulence, diarrhea and allergic itching, rash or hives are listed; frequency not known.[1]
- Long-term use
- The EU monograph says long-term use is possible; adverse events were fewer than on placebo over 12 months.[1][3]
- Fresh plant
- Applying fresh leaves stings the skin by design; that sting was the intervention in the thumb-pain trial.[9]
How to read the label
- Label dose vs clinical doseThe 12-month prostate trial used 459 mg/day of root dry extract; EU-listed root extracts range from about 300 to 960 mg/day depending on the extract.[3][1]
- Root vs leafProstate products use the root; blood sugar trials mostly used the leaf. They are not interchangeable.[1][5]
- Combination productsMany prostate products pair nettle root with saw palmetto; the tested combination used 160 mg saw palmetto and 120 mg nettle root per capsule, twice daily.[2]
- Traditional, not proven, statusThe EU registers nettle root on long-standing use, not on proof of efficacy.[1]
Cost per studied dose, without the sales pitch
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Cost per studied dose
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Frequently asked questions
Does stinging nettle help an enlarged prostate?
Modestly. In a 12-month trial in 246 men, root extract improved symptom scores slightly more than placebo but did not improve urine flow.[3]
Does nettle lower blood sugar?
Meta-analyses of small trials found fasting glucose about 17–18 mg/dL lower in type 2 diabetes, with very inconsistent results between trials.[5][11]
Does nettle help hay fever?
Evidence is weak: one week of freeze-dried nettle was rated only slightly better than placebo, and a 1-month root extract trial found placebo did as well.[7][8]
Is nettle root the same as nettle leaf?
No. The root is used for prostate symptoms and the leaf in blood sugar and allergy studies.[1][5]
Does nettle interact with medicines?
The EU monograph reports no interactions. Because nettle leaf lowered glucose in trials, people on diabetes medicines may see lower readings.[1][10]
What are the side effects?
Stomach upset, heartburn, bloating, diarrhea and allergic skin reactions are listed.[1]
Sources
- [1]European Union herbal monograph on Urtica dioica L.; Urtica urens L., radix (final, Revision 1, adopted 22 January 2025). European Medicines Agency, Committee on Herbal Medicinal Products, 2025. guideline
- [2]Long-term efficacy and safety of a combination of sabal and urtica extract for lower urinary tract symptoms--a placebo-controlled, double-blind, multicenter trial.. World J Urol, 2005. RCT
- [3][Stinging nettle root extract (Bazoton-uno) in long term treatment of benign prostatic syndrome (BPS). Results of a randomized, double-blind, placebo controlled multicenter study after 12 months].. Urologe A, 2004. RCT
- [4]Phytotherapy for benign prostatic hyperplasia.. Public Health Nutr, 2000. meta-analysis
- [5]Effects of Urtica dioica on Metabolic Profiles in Type 2 Diabetes: A Systematic Review and Meta-analysis of Clinical Trials.. Mini Rev Med Chem, 2022. meta-analysis
- [6][Status of phytotherapeutic drugs in treatment of benign prostatic hyperplasia].. Urologe A, 1995. review
- [7]Randomized, double-blind study of freeze-dried Urtica dioica in the treatment of allergic rhinitis.. Planta Med, 1990. RCT
- [8]Efficacy of Supportive Therapy of Allergic Rhinitis by Stinging Nettle (Urtica dioica) root extract: a Randomized, Double-Blind, Placebo- Controlled, Clinical Trial.. Iran J Pharm Res, 2017. RCT
- [9]Randomized controlled trial of nettle sting for treatment of base-of-thumb pain.. J R Soc Med, 2000. crossover-RCT
- [10]Improved glycemic control in patients with advanced type 2 diabetes mellitus taking Urtica dioica leaf extract: a randomized double-blind placebo-controlled clinical trial.. Clin Lab, 2013. RCT
- [11]The effect of nettle (Urtica dioica) supplementation on the glycemic control of patients with type 2 diabetes mellitus: A systematic review and meta-analysis.. Phytother Res, 2020. meta-analysis
- [12]Urtica dioica in comparison with placebo and acupuncture: A new possibility for menopausal hot flashes: A randomized clinical trial.. Complement Ther Med, 2019. RCT
What changed
- First draft. Every PMID checked against NCBI E-utilities esummary (title and year taken from the record) and abstracts read for the cited rows.
- Adversarial review pass: every evidence row re-read against its PubMed abstract. Official sources opened before citing: EMA/HMPC EU herbal monograph on nettle root (Revision 1, adopted 22 January 2025; traditional-use indication, posology, warnings, interactions none reported, undesirable effects). No ODS fact sheet or NCCIH page exists for stinging nettle (NCCIH A–Z and herbs-at-a-glance checked). Integrity: the 620-man BPH crossover trial by M. R. Safarinejad (PMID 16635963) was left out of the evidence table and grading because several other trials by the same sole author have been retracted (e.g., PMIDs 19453924, 19138369). Industry ties: the 2017 rhinitis trial was university-funded (PMC5963652); funding for the root and combination BPH trials is not stated in PubMed. Retraction, expression-of-concern, erratum and withdrawn checks on all 11 PMIDs: none flagged. Page set indexable. Independent browser review (4 parallel reviewers, every evidence row checked against its abstract and official sources on the Vercel preview) found: no factual errors; blood-sugar insight now states that the >90% heterogeneity refers to fasting glucose.