Stinging nettle root

What is stinging nettle root?

Stinging nettle (Urtica dioica) is a common plant whose leaves sting on contact. Different parts are used for different purposes: the leaf is used in herbal teas and for allergies, while the root has long been used in Europe for urinary complaints associated with an enlarged prostate (BPH). Root preparations contain lignans, sterols, polysaccharides and a lectin known as UDA.

What the research says

A comprehensive 2007 review concluded that nettle root’s mechanism is still unclear and that laboratory findings may not translate to clinical effects. The clinical evidence rests largely on open (unblinded) studies, with a small number of randomized trials suggesting benefit from a particular proprietary extract. The reviewers said the significance and size of the effect still needed confirmation before nettle root could be accepted in BPH treatment guidelines, and they described the risk of side effects as very low (Chrubasik et al., 2007).

One six-month randomized trial in 620 men reported large improvements in symptom scores and urine flow with nettle root compared with placebo, plus a modest reduction in prostate size, with no change in PSA or testosterone (Safarinejad, 2005). The results were striking but came from a single center and have not been reproduced at that scale, so they should be read with caution.

Nettle root is often studied together with saw palmetto. A combination product (160 mg saw palmetto plus 120 mg nettle root per capsule, taken twice daily) was followed for 96 weeks in a trial that began with a placebo-controlled phase; symptom scores and flow improved over the study (Lopatkin et al., 2007). However, a 2023 Cochrane review rated the evidence for saw palmetto combinations as low certainty (Franco et al., 2023).

How it’s used in supplements

Nettle root extract appears in many prostate formulas, sometimes with saw palmetto, pygeum or pumpkin seed. Studied amounts vary and depend on the extract type, so it is hard to compare a generic 200 mg “extract” with trial products.

Nettle root is generally well tolerated; mild stomach upset is the most common complaint. Because it may affect fluid balance, blood sugar and blood pressure, people taking diuretics, diabetes medicines, blood pressure medicines, lithium or blood thinners should check with a doctor. It should not be used to self-treat urinary symptoms before a medical evaluation, since those symptoms can have several causes, some serious.