What is nettle root? Today, nettle root is used to treat urinary problems associated with an enlarged prostate (benign prostatic hyperplasia), urinary tract infections and hay fever. Nettle leaf, meanwhile, is most commonly used to treat pain, osteoarthritis, allergies and hay fever. The leaves and stems can be eaten in a salad, cooked into soup or made into a tea, but the nettle root is more likely to be extracted with alcohol to make a tincture, dried and taken in capsules, or dried and made into a tea. The plant has few known side effects, but as with any medicinal preparation, you may want to consult a health care practitioner before adding nettles to your diet or treatment plan.