context: Stinging nettle is a plant that grows in North America, Europe, and Africa. It has been used as an herbal remedy for thousands of years. The name comes from the stinging sensation that you get when you brush against the plant's hairy stem and leaves. People take stinging nettle to try to treat health problems, including: Benign prostatic hyperplasia ( BPH). Stinging nettle root is a common treatment in Europe for symptoms of BPH. This is a noncancerous condition that causes the prostate gland to enlarge, making urination difficult. Some research shows that stinging nettle root may be helpful in treating this problem. Experts are not sure which components in the plant may have an effect on BPH, if any. More research is needed to show that the treatment is indeed effective. Allergies. Stinging nettle leaf may be useful in reducing the symptoms of hay fever by acting as an anti-inflammatory. Some research has linked treatment with stinging nettle leaf to relief of symptoms such as sneezing, runny nose, and itchy eyes. But more well-designed studies are needed to confirm this effect. Joint pain. Research has found some evidence that rubbing stinging nettle leaves on painful joints can provide pain relief. One small study also found that eating stewed nettle leaves was a helpful addition to the anti-inflammatory drug diclofenac. People have also used stinging nettle as a diuretic -- a treatment that causes the body to shed more water in the urine. Research has found this effect from stinging nettle in rats. Optimal doses of stinging nettle have not been set for any condition. Quality and active ingredients in supplements may vary widely from maker to maker. This makes it hard to set a standard dose. Stinging nettle can be eaten on its own or as an ingredient in foods. Nettle leaves must first be cooked or steamed to destroy the hairs on them, which contain a number of irritating chemicals. Most medicinal uses of stinging nettle use more of the plant than you would typically eat. Side effects. Exposure to plant hairs or juice typically causes: Burning Itching Rash Stinging nettle may cause: Low blood pressure Higher or lower blood sugar levels Digestive discomfort It may also encourage bleeding and cause uterine contraction. Risks. Avoid stinging nettle if you're allergic or sensitive to nettle or plants in the same family. Avoid if you're pregnant or breastfeeding because there isn't enough information on its safety. Use with caution if you're elderly because of the potential of causing low blood pressure. And use stinging nettle with caution if you have diabetes because of the potential that it may lower or raise blood sugar levels. Interactions. Stinging nettle may interact with some medications, so use with caution if you're taking: Blood-thinning drugs Diuretics Blood pressure drugs Anti-inflammatory drugs Stinging nettle may also interact with alpha-blockers, finasteride, and other drugs. And it may interact with other herbs and supplements. Tell your doctor about any supplements you're taking, even if they're natural. That way, your doctor can check on any potential side effects or interactions with any medications. Supplements are not regulated by the FDA.