From the Manufacturer:
Nettles, specifically stinging nettles, have a long history of medicinal use. It has been used internally as a diuretic and for other problems, and applied externally for stimulation. In modern times nettles have been used for several different conditions. One of the most popular applications for nettle is as a treatment for urinary problems related to enlarged prostate (benign prostatic hyperplasia [BPH]). It is often combined with saw palmetto to treat reduced urinary flow, post urination dripping and the constant urge to urinate. Nettle has a broader application to urinary tract infections and is believed to be beneficial in preventing kidney stones.
During allergy season some individuals have found nettles to be beneficial in reducing the symptoms of hay fever. Studies have also shown nettles to be beneficial in treating osteoarthritis particularly when combined with anti-inflammatory medications.