Nettle Root / Leaf

Medically reviewed by Prof. Giorgi Pkhakadze, MD, MPH, PhD — GMJ Editorial Board

Scientific name: Urtica dioica
Category: Herbal extract
RDA: Not established
UL: Not established

What is Nettle Root / Leaf?

Nettle (Urtica dioica), commonly known as stinging nettle, is a perennial flowering plant that has been used medicinally for centuries. Both the root and leaf portions of the plant are utilized in dietary supplements, though they contain different active compounds and are traditionally used for different purposes. The leaves are rich in vitamins, minerals, and phenolic compounds, while the root contains unique polysaccharides, lignans, and sterols. Nettle supplements are available as dried powders, extracts, teas, and capsules, with standardized preparations ensuring consistent potency of active compounds.

Health benefits & uses

Moderate evidence:

Submit Your Paper

• Benign prostatic hyperplasia (BPH): Nettle root extract has shown promise in reducing symptoms of enlarged prostate, including improved urinary flow and reduced nighttime urination frequency in several clinical trials.
• Allergic rhinitis: Nettle leaf may help reduce hay fever symptoms, with studies showing improvements in sneezing, nasal congestion, and itching compared to placebo.

Limited evidence:

• Anti-inflammatory effects: Laboratory studies suggest nettle extracts may reduce inflammatory markers, though human clinical data remains limited.
• Blood sugar support: Some small studies indicate nettle leaf may help with glucose metabolism, but larger trials are needed.
• Joint discomfort: Traditional use and preliminary studies suggest potential benefits for arthritis symptoms, though evidence is not conclusive.
• Blood pressure support: Animal studies show potential cardiovascular benefits, but human evidence is insufficient.

How it works

Nettle’s therapeutic effects stem from its diverse array of bioactive compounds. The leaves contain flavonoids like quercetin and kaempferol, which contribute to anti-allergic and anti-inflammatory properties by stabilizing mast cells and reducing histamine release. Nettle root contains beta-sitosterol and other phytosterols that may inhibit 5-alpha-reductase, an enzyme involved in prostate enlargement. The plant also provides lectins and polysaccharides that may modulate immune function. Additionally, nettle’s high mineral content, including iron, potassium, and silica, may contribute to its traditional use as a nutritive tonic. The anti-inflammatory effects appear to work through multiple pathways, including inhibition of cyclooxygenase and lipoxygenase enzymes.

Dosage

Typical adult dosages vary depending on the form and intended use:

• Nettle leaf extract: 300-600 mg daily, standardized to contain 1% silica
• Nettle root extract: 120-300 mg twice daily, often standardized to beta-sitosterol content
• Dried nettle leaf: 2-4 grams daily as tea or in capsules
• Fresh nettle juice: 10-15 mL daily

No official RDA or UL has been established. Duration of use varies by condition, with some studies using nettle for 2-6 months. Always consult a healthcare provider before starting supplementation, especially for specific health conditions like BPH, where medical supervision is important.

Food sources

Fresh nettle leaves can be consumed as food when properly cooked, as cooking neutralizes the stinging compounds. Young nettle shoots are harvested in spring and can be steamed, sautéed, or added to soups and stews, providing a spinach-like green vegetable rich in vitamins A and C, iron, and potassium. Nettle tea, made from dried leaves, is widely available. However, therapeutic doses of active compounds typically require concentrated extracts rather than food sources. Nettle root is not commonly consumed as food and is primarily available as a supplement extract.

Safety & side effects

Nettle supplements are generally well-tolerated when used appropriately. Common mild side effects may include:

• Stomach upset or nausea when taken on an empty stomach
• Mild diuretic effects
• Skin reactions in sensitive individuals

Fresh nettle plants cause stinging and burning sensations when touched due to histamine and formic acid in the plant hairs, but processed supplements do not cause this reaction. Quality supplements from reputable manufacturers undergo testing for contaminants and proper processing to ensure safety.

Interactions

Potential drug interactions include:

• Blood thinners (warfarin): Nettle may enhance anticoagulant effects due to vitamin K content
• Blood pressure medications: May have additive hypotensive effects
• Diabetes medications: Could potentially affect blood sugar levels
• Diuretics: May enhance diuretic effects
• Lithium: Diuretic effects may reduce lithium elimination

Supplement interactions are less well-documented but exercise caution when combining with other herbs that affect blood pressure, blood sugar, or have diuretic properties.

Who should be cautious

Certain individuals should exercise particular caution or avoid nettle supplements:

• Pregnant and breastfeeding women due to insufficient safety data
• People with kidney disease, as nettle has diuretic properties
• Individuals with diabetes who take medication, due to potential blood sugar effects
• Those scheduled for surgery, as nettle may affect blood clotting
• People with known allergies to plants in the Urticaceae family
• Individuals taking multiple medications should consult healthcare providers about potential interactions

Frequently asked questions

Is there a difference between nettle root and leaf supplements?

Yes, nettle root and leaf contain different active compounds and are used for different purposes. Root extracts are primarily used for prostate health, while leaf preparations are more commonly used for allergies and as a general nutritive supplement. The root contains higher concentrations of sterols and lignans, while leaves are richer in flavonoids and minerals.

How long does it take to see benefits from nettle supplements?

The timeline varies by condition and individual response. For seasonal allergies, some people report benefits within days to weeks. For prostate health, studies typically show improvements after 4-8 weeks of consistent use. Always maintain realistic expectations and consult healthcare providers for persistent symptoms.

Can nettle supplements replace allergy medications?

Nettle should not replace prescribed allergy medications without medical supervision. While some studies show promise for mild allergic rhinitis, nettle supplements are best viewed as complementary support rather than primary treatment for significant allergic conditions.

Are nettle supplements safe for long-term use?

While nettle has a long history of traditional use, long-term safety data for concentrated supplements is limited. Most studies use nettle for periods of several months. For extended use beyond 6 months, periodic consultation with a healthcare provider is advisable to monitor for any adverse effects.

Can I grow and prepare my own nettle supplements?

While nettle can be grown and harvested, proper identification, timing of harvest, and processing methods are crucial for safety and effectiveness. Commercial supplements provide standardized potency and undergo safety testing. If choosing to use fresh nettle, proper cooking or drying is essential to neutralize stinging compounds, and therapeutic doses may be difficult to achieve through home preparation.