Limited evidenceMen's health

Stinging Nettle

Nettle root produced a statistically significant but clinically trivial improvement in prostate symptom scores in its largest trial, with no change in urine flow or residual volume. The leaf's allergy and joint claims rest on single small studies that were never replicated.

What the science says

Benign prostatic hyperplasia symptoms Limited evidence
In a 12-month randomised trial of 246 men, 459 mg/day of nettle root dry extract lowered IPSS from 18.7 to 13.0 versus 18.5 to 13.8 on placebo (p = 0.023) — a difference of well under one point on a 35-point scale. Peak urinary flow and residual urine volume did not differ significantly from placebo.
Allergic rhinitis Limited evidence
The frequently cited evidence is a single 1990 trial of 98 patients given 600 mg/day of freeze-dried nettle leaf for one week, which found it rated moderately better than placebo on global assessment only. It has not been replicated in 35 years.
Joint pain, blood sugar and blood pressure Limited evidence
These claims come from preclinical work and a few very small trials, often using combination products or topical application. There is no adequate human evidence that oral nettle helps arthritis, glycaemic control or hypertension.

Dosage & safety

Studied doseRoot (for urinary symptoms): 360-600 mg/day of standardised dry extract, often 120 mg twice daily, for 3-12 months. Leaf (for rhinitis): 600 mg of freeze-dried leaf, up to three times daily. Root and leaf are chemically distinct products used for different purposes — check which one you are buying.

SafetyGenerally mild: gastrointestinal upset, sweating and occasional rash. Nettle has diuretic and mild blood-pressure- and glucose-lowering effects, so it can add to the action of diuretics, antihypertensives and diabetes medication, and may raise lithium levels through fluid shifts. Nettle leaf is high in vitamin K and may reduce the effect of warfarin. Avoid in pregnancy (uterine stimulant activity reported). Handling the raw plant causes contact urticaria. Nettle root is not a substitute for proper assessment — obstructive urinary symptoms need a prostate evaluation.

Scientific references

[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]
Schneider T, Rübben H — Der Urologe. Ausg. A, 2004
Randomized, double-blind study of freeze-dried Urtica dioica in the treatment of allergic rhinitis
Mittman P — Planta Medica, 1990

Where to buy

Swanson Vitamins, Stinging Nettle Root, 500 mg, 100 Capsules

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