Bottom Line: There is no proof that nettle alone can treat benign prostatic hypertrophy (BPH), since it has always been used in combination with other herbs in clinical trials. There is no evidence for any other effects.
Researchers are still unsure how nettle works. It has been suggested that nettle might reduce the activity of testosterone by altering the amount of testosterone circulating in the blood, or by inhibiting one of the key enzymes in testosterone synthesis. However, none of these theories has been conclusively proven. Other actions of nettle include acting as a diuretic (causing water loss from the body through the urine) and lowering blood pressure. Some compounds in nettle might also reduce inflammation.
To treat allergies No scientific evidence supports this use.
To treat arthritis One small clinical trial supports the topical use of nettle sting for arthritis of the hand, but more clinical trials are needed.
To treat benign prostatic hypertrophy (BPH) When combined with other herbs, nettle has shown positive results in two clinical trials, but there is no proof from clinical trials that nettle alone can treat BPH.
To clear up chest congestion No scientific evidence supports this use.
To promote urination Nettle is a known diuretic.
To reduce inflammation Nettle may have anti-inflammatory activities, but there is no proof from clinical trials that this effect occurs in humans.
To treat oily skin No scientific evidence supports this use.
To calm muscle spasms No scientific evidence supports this use.
To treat urinary tract disorders and relieve difficult or painful urination The only clinical trials studying this use have used herbal combinations to treat the urinary symptoms associated with BPH, with positive results. It is not known if most of the beneficial effects are from nettle or from the other herbs.
Benign prostatic hypertrophy (BPH): Not many clinical trials have used nettle by itself. A few clinical trials have used nettle in combination with other herbs for the treatment of benign prostatic hypertrophy (BPH), with positive results. The results of these trials do not definitively support the use of nettle, however, since it is unclear how much of the positive response was due to nettle compared to the other herbal ingredients.
Nature's Way Products, Inc., has recalled four lots of its 100-count nettle capsules due to lead contamination. The lot numbers are 131237, 131238, 140738, 215229. More information is available at: http://www.fda.gov/oc/po/firmrecalls/nettle06_02.html.
This product is regulated by the FDA as a dietary supplement. Unlike approved drugs, supplements are not required to be manufactured under specific standardized conditions. This product may not contain the labeled amount or may be contaminated. In addition, it may not have been tested for safety or effectiveness.
Derived from the root of the plant, Nettle is used to treat benign prostatic hypertrophy (BPH), allergies, and inflammation. Several components appear to account for its activity, although the precise mechanism of action is unknown. Nettle is usually combined with other herbs, such as saw palmetto. One in vitro study indicates nettle extract may have antiproliferative effects on human prostate cancer cells (7). A recent study done in Europe suggests that nettle root extract is effective in treating benign prostatic syndrome (BPS) (9). Adverse effects include GI upset, sweating, and contact dermatitis (5). Enhanced activity of diclofenac has been reported when combined with nettle, but this is of unknown clinical significance. Theoretically, nettle may have an additive effect with diuretics (4).
The mechanism of action remains unknown. It has been postulated that the herb may have an effect on the amount of free (active) testosterone circulating in the blood, or it may inhibit one of the key enzymes, aromatase, responsible for testosterone synthesis. Another, more recent theory attributes the activity to the presence of a lectin (protein) mixture designated UDA (Urtica dioica agglutinin) and several polysaccharides. None of these various postulates regarding its activity is conclusively proven. Nettle also acts as a diuretic and decreases systolic blood pressure. Scopoletin as an active ingredient has anti-inflammatory activity. (2)
Nature's Way Products, Inc., has recalled four lots of its 100-count nettle capsules due to lead contamination. The pertinent lot numbers are 131237, 131238, 140738, 215229. More information is available at: http://www.fda.gov/oc/po/firmrecalls/nettle06_02.html.
Diclofenac: Action of diclofenac was enhanced by nettle extract. This may be due in part to inhibition of cyclooxygenase products and possibly to inhibition of cytokine release, as evidenced by a reduction in whole blood of induced tumor necrosis factor alpha and interleukin -1B. Diuretics: Theoretically nettle may have additive effect due to diuretic activity. (4)
A randomized, double-blind, placebo controlled trial was performed on 246 patients with benign prostatic syndrome (BPS). The results indicate that nettle root extract is effective in reducing symptoms associated with BPS (9). Nettle in combination with other herbs has had fair results in BPH. The majority of studies have been performed in animals.
