Stinging nettle (Urtica dioica) is a flowering plant used to treat benign prostatic hyperplasia (BPH), allergies, arthritis and inflammation.
While the precise mechanism of action is unclear, several compounds have been isolated from nettle including flavonoid glycosides that appear to contribute to its biological effects (1).
Growing in vitro and animal studies show its potential to treat a wide range of other diseases and conditions, including colitis and cancer as well as having kidney and liver protective properties.
Stinging nettle is effective in the treatment of benign prostatic hyperplasia (BPH). BPH is an enlarged prostate — a condition that is common in aging men. As the prostate enlarges, it can press against the urethra. The bladder wall eventually becomes thicker and the bladder may weaken and lose the ability to empty completely. The narrowing of the urethra and the inability to empty the bladder completely, cause many of the problems associated with BPH (2).
In a six-month study, researchers evaluated the ability of stinging nettle to provide symptomatic relief of lower urinary tract symptoms (LUTS) secondary to BPH. The comparative study of stinging nettle and placebo was performed in 558 patients.
At the end of the study, 81 percent of 287 patients in the stinging nettle group reported improved LUTS compared with 16 percent of 271 patients in the placebo group. In addition, the peak flow rates of the participants improved by 3.4 mL/s for placebo recipients and by 8.2 mL/s for treated patients. A modest decrease in prostate size was seen in the treated group, compared to no change in the placebo group.
At the 18-month follow-up, only patients who continued therapy experienced an improvement in symptoms. No side effects were identified in either group (3).
Stinging nettle may help improve symptoms of osteoarthritis. In 27 patients with osteoarthritic pain at the base of the thumb or index finger, the application of stinging nettle daily for one week improved symptoms. Score reductions on both pain and disability were significantly greater than with placebo (4).
Osteoarthritis is a chronic condition of the joints causing pain, swelling and problems moving the joint (5).
In another exploratory study, stinging nettle brought pain relief to those suffering from joint pain. Eighteen patients using stinging nettle were interviewed, and all but one participant reported that treatment was very helpful, and several considered themselves cured.
The only side effects reported were temporary hives (6).
Stinging nettle may help treat colitis. Colitis is a chronic disease of the large intestine in which the lining of the colon becomes inflamed and develops tiny open sores, or ulcers, that produce pus and mucous. The combination of inflammation and ulceration can cause abdominal discomfort and frequent emptying of the colon (7).
In a study of rats induced with colitis, stinging nettle was found to be effective in improving colonic inflammation. Supplementation decreased levels of pro-inflammatory cytokines, triglyceride, cholesterol and lactate dehydrogenase (LDH). LDH is an enzyme present in essentially all major organ systems. The extracellular appearance of LDH is used to detect cell damage or inflammation (8).
Researchers concluded that stinging nettle, through its anti-inflammatory and antioxidant actions, merits further study as a potential agent in improving colonic inflammation (9).
Stinging nettle may have anticancer potential. The results of an in vitro study published in the journal, Planta Medica, reported on the anti-proliferative effects of methanolic extract of stinging nettle roots in human prostate cancer cells (10).
In another study, researchers found that methanolic extract of stinging nettle provides protection against toxicity caused by the cancer drug Cisplatin. This drug is a widely used cancer-killing agent, yet high doses have been known to cause kidney and liver toxicity.
It is believed that its protective capacity is probably due to promoting antioxidative defense systems (11).
In another study, researchers found that extract of stinging nettle inhibited cancer cell growth and migration. In addition, the extract substantially increased sensitivity of breast cancer cells to the chemotherapy drug Paclitaxel (12).
Stinging nettle helps alleviate nasal congestion. After one week of supplementing with a freeze-dried preparation of stinging nettle, a global assessment of allergic symptoms was conducted and the daily diaries of people with allergies collected.
The usage of stinging nettle was associated with a small decrease of symptoms of allergies.
According to the global assessment, usage of stinging nettle was better than placebo at reducing the allergic response to whatever subjects were allergic to (13).
Stinging nettle may improve glycemic control in type-2 diabetic patients. In 2013, the efficacy and safety of stinging nettle leaf extract in the treatment of patients with advanced type 2 diabetes mellitus needing insulin was evaluated in a clinical trial.
At the endpoint of the trial, nettle leaf extract (one 500 mg capsule be 8 hours for 3 months) lowered the blood levels of fasting glucose, 2 hours postprandial glucose and HbA1c significantly compared with placebo (14).
True to its name, stinging nettle produces a stinging and burning sensation when the hairs or spines on the stems and leaves of the plant come in contact with skin.
The plant causes the release of several biologically active substances, and the released chemicals cause itching, dermatitis and hives within moments of contact (15).
Combining stinging nettle with hypertension drugs may cause blood pressure to become too low.
There is some evidence that stinging nettle can decrease blood sugar levels and may intensify the effects of drugs that increase urination (diuretics).
120mg of stinging nettle (root) taken three times a day is associated with benefitting benign prostate hyperplasia.
For allergies, the studied dosage is 300 mg twice a day of freeze-dried nettle leaf.
Stinging nettle is a plant used traditionally to treat benign prostatic hyperplasia (BPH), allergies, osteoarthritis and inflammation.
Several compounds have been isolated from nettle including flavonoid glycosides that appear to contribute to its biological effects (16).
Growing in vitro and animal studies show its potential to treat a wide range of other diseases and conditions, including colitis, cancer and type-2 diabetes.
The leaves and the stems have fine hairs that contain irritating chemicals, which are released upon contact with the skin. As a result, touching the plant can cause itching, rash and hives.