Nettle is known for its ability to relieve symptoms of benign prostatic hypertrophy (BPH), a condition in which the prostate becomes enlarged and causes men to develop problems with urination. Nettle helps men to urinate more successfully during the day, and thus helps eliminate another annoying symptom of BPH—frequent nighttime urination. Nettle keeps the body from converting testosterone into 5-alpha-reductase, an enzyme that causes the prostate gland to begin growing again in middle age. Taking nettle in combination with either pygeum bark extract or saw palmetto may be to be at least as effective against BPH as the prescription drug finasteride. Commission E also approves the use of nettle to treat BPH.