Stinging nettle (Urtica dioica and the closely related Urtica urens) has a long medicinal history. In medieval Europe, it was used as a diuretic (to rid the body of excess water) and to treat joint pain.
Stinging nettle has fine hairs on the leaves and stems that contain irritating chemicals that are released when the plant comes in contact with the skin. While the hairs, or spines, of the stinging nettle are normally very painful to the touch, when they come into contact with a painful area of the body, they can actually decrease the original pain. Scientists think nettle does this by reducing levels of inflammatory chemicals in the body, and by interfering with the way the body transmits pain signals.
General Uses
Stinging nettle has been used for hundreds of years to treat painful muscles and joints, eczema, arthritis, gout, and anemia. Today, many people use it to treat urinary problems during the early stages of an enlarged prostate (called benign prostatic hyperplasia or BPH), for urinary tract infections, for hay fever (allergic rhinitis), or in compresses or creams for treating joint pain, sprains and strains, tendonitis, and insect bites.
Benign Prostatic Hyperplasia (BPH)
Stinging nettle root is used widely in Europe to treat BPH, or enlargement of the prostate. Studies in people suggest that stinging nettle, in combination with other herbs (especially saw palmetto), may be effective at relieving symptoms such as reduced urinary flow, incomplete emptying of the bladder, post urination dripping, and the constant urge to urinate. These symptoms are caused by the enlarged prostate gland pressing on the urethra (the tube that empties urine from the bladder). Laboratory studies have shown stinging nettle to be comparable to finasteride (a medication commonly prescribed for BPH) in slowing the growth of certain prostate cells. However, unlike finasteride, the herb does not decrease prostate size. Scientists aren't sure why nettle root reduces symptoms; it may be because it contains chemicals that affect hormones (including testosterone and estrogen), or because it directly acts on prostate cells. It is important to work with a doctor to treat BPH, and to make sure you have a proper diagnosis to rule out prostate cancer.
Osteoarthritis
The leaves and stems of nettle have been used historically to treat arthritis and for sore muscles. Studies have been small and not conclusive, but they do suggest that some people find relief from joint pain by applying nettle leaf topically to the painful area. A few other studies show that taking an oral extract of stinging nettle along with nonsteroidal anti-inflammatory drugs (NSAIDs) allowed people to reduce their NSAID dose.
Hay fever
One preliminary human study suggested that nettle capsules helped reduce sneezing and itching in people with hay fever. Researchers think that may be due to nettle's ability to reduce the amount of histamine the body produces in response to an allergen. More studies are needed to confirm nettle's antihistamine properties, however. Some doctors recommend using a freeze-dried preparation of stinging nettle and to begin taking it well before hay fever season starts.
Other
Some preliminary animal studies indicate that nettle may lower blood sugar and blood pressure, but there is not enough evidence to say whether this would also be true in humans.
Stinging nettle is the name given to common nettle, garden nettle, and hybrids of these two plants. Originally from the colder regions of northern Europe and Asia, today this herbaceous shrub grows all over the world. Stinging nettle grows well in nitrogen-rich soil, blooms between June and September, and usually reaches 2 - 4 feet high.
Stems are upright and rigid. The leaves are heart-shaped, finely toothed, and tapered at the ends, and flowers are yellow or pink. The entire plant is covered with tiny stiff hairs, mostly on the underside of the leaves and stem, that release stinging chemicals when touched.
The use of herbs is a time-honored approach to strengthening the body and treating disease. Herbs, however, can trigger side effects and can interact with other herbs, supplements, or medications. For these reasons, herbs should be taken with care, under the supervision of a health care practitioner.
Stinging nettle is generally considered safe when used as directed. Occasional side effects include mild stomach upset, fluid retention, and hives or rash (mainly from topical use). It is important to be careful when handling the nettle plant because touching it can cause an allergic rash. Stinging nettle should never be applied to an open wound.
Because nettle can alter the menstrual cycle and may contribute to miscarriage, pregnant women should not use nettle.
Do not self-treat with nettle for BPH; see your doctor to receive a diagnosis and to rule out prostate cancer.
Antiplatelet and anticoagulant drugs (blood-thinners) -- Stinging nettle may affect the blood's ability to clot, and could interfere with any blood-thinning drugs you are taking, including:
- Warfarin (Coumadin)
- Clopidogrel (Plavix)
- Aspirin
Drugs for high blood pressure -- Stinging nettle may lower blood pressure, so it could make the effects of these drugs stronger:
- ACE inhibitors: Captpril (Capoten), Elaropril (Vasotec), lisinopril (Zestril), fosinopril (Monopril)
- Beta blockers: Atenolol (Tenormin), metoprolol (Lopressor, Toprol XL), propranolol (Induran)
- Calcium channel blockers: Nifedipine (Procardia), amlodipine (Norvasc), verapamil (Calan, Isoptin)
Diuretics (water pills) -- Because stinging nettle can act as a diuretic, it can increase the effects of these drugs, raising the risk of dehydration:
- Furosemide (Lasix)
- Hydrocholorothiazide
Drugs for diabetes -- Stinging nettle may lower blood sugar, so it could make the effects of these drugs stronger, raising the risk of hypoglycemia (low blood sugar).
Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) -- In a scientific study of patients with acute arthritis, stewed stinging nettle leaves enhanced the anti-inflammatory effect of diclofenac, an NSAID. Although the effect can reduce pain, you should talk to your doctor before taking or using stinging nettle if you also take NSAIDs.
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