Stinging nettle (particularly the roots) has been used to treat BPH. It is thought to decrease the size of the prostate gland, and to improve the urinary symptoms associated with an enlarged prostate. [1][2] It is also sometimes used to treat other urinary tract disorders, and some studies have supported the use of stinging nettle to prevent and treat kidney stones, as the flavonoids and saponins found in the nettle are able to disintegrate oxalate stones.[3][4]
Stinging nettle has been used in arthritis in general, as it is thought to have some analgesic and anti-inflammatory properties. While some observational studies have shown the potential use of stinging nettle supplements for arthritis, there are no formal clinical trials to support these claims. Through similar mechanisms, stinging nettle could be useful in other diseases that cause musculoskeletal pain. Observed decreases in joint pain, improved mobility, and stiffness are positive findings that warrant further research.[5][6][7]
Stinging nettle has been studied in diabetes, and has been shown to lower fasting blood sugar levels.[8][9] While this could be helpful, the nettle extracts studied did not improve glycated hemoglobin, also referred to as HbA1c, which reflects average blood sugar over a period of months. Although a rat study found that stinging nettle improved pancreatic function, and therefore insulin levels,[5] human clinical trials have not found that stinging nettle supplementation improved insulin levels.[8][9]
In allergic rhinitis, a handful of trials found that stinging nettle supplements decreased symptoms more than placebo. Although this is being a popular use of the supplement, there is not a lot of evidence to support it.[10][11][5]
Due to its antioxidant and antiproliferative (i.e., cell-growth-suppressing) effects, stinging nettle has been studied for cancer prevention and/or treatment. In vitro studies have shown that it induces apoptosis (the programmed death of unwanted cells) in prostate cancer cells, colon cancer cells, and gastric cancer cells.[12][13][14] In breast cancer cells, stinging nettle also induced apoptosis and slowed proliferation in certain types of breast cancers in vitro.[15]PMID29506637[16][17][18] Stinging nettle might also be helpful at increasing sensitivity to some chemotherapeutic agents for breast cancer, namely paclitaxel[19] and cisplatin.[20] In acute myeloid leukemia (AML), stinging nettle leaf tea had antiproliferative effects on the leukemic cells in vitro and induced apoptosis in them; some of the phenolic compounds in the tea were also found to have antitumor effects.[21] While these results are all promising, clinical trials in humans will need to be done to confirm these effects.
Stinging nettle has also been used topically to prevent hair loss, and in combination medications as an antihemorrhagic agent (i.e., one that stops bleeding), but there is minimal evidence to support these uses.[22][23][24]