Stinging Nettle
Urtica dioica
The leaf and aerial parts of the common nettle, a mineral-rich traditional food and remedy studied for hay fever, arthritis pain, and blood sugar, distinct from nettle root used for prostate symptoms.
At a Glance
- Best known for
- May ease seasonal allergy symptoms (hay fever), Anti-inflammatory; studied for osteoarthritis pain, Rich source of minerals (calcium, iron, magnesium) and vitamin K
- Evidence
- Preliminary
- Typical dose
- 300 mg freeze-dried leaf 2–3x daily
- Type
- Herb
What is Stinging Nettle?
Stinging nettle (Urtica dioica) is a perennial plant found on every continent except Antarctica, recognized by the tiny hollow hairs on its leaves and stems that inject formic acid, histamine, and other irritants when touched. Despite the sting, it has been eaten as a cooked spring green and used medicinally for thousands of years; Roman soldiers reputedly flogged themselves with nettles to stay warm, and 'urtication' (deliberately stinging arthritic joints) is a folk remedy that has actually been tested in a clinical trial. The leaf (aerial parts) and the root are used for different purposes: leaf for allergies, inflammation, and nutrition; root for prostate symptoms. This entry covers the leaf.
Known Health Benefits
How It Works
Nettle leaf extracts inhibit several inflammatory pathways: they reduce NF-κB activation and the production of TNF-α and IL-1β, inhibit COX and 5-lipoxygenase enzymes, and in laboratory studies block the release of pro-inflammatory cytokines from immune cells. For allergies, nettle appears to act as a mild antagonist at the histamine H1 receptor and to inhibit mast cell tryptase and prostaglandin D2 production, reducing the histamine cascade. Its diuretic effect increases urine volume and sodium excretion. Compounds in nettle improve insulin secretion and glucose uptake in animal models. The dense mineral and chlorophyll content underlies its traditional use as a nourishing tonic for anemia and fatigue.
What Research Says
Clinical evidence for nettle leaf is modest. A 1990 double-blind trial of 98 people with allergic rhinitis found freeze-dried nettle (300 mg twice daily) rated moderately or highly effective by 58% of participants versus 37% on placebo, a small difference that has not been well replicated. A 2000 study of 27 people with osteoarthritis of the thumb found that applying fresh stinging nettle leaf to the joint daily for a week reduced pain and disability compared with a placebo plant. Small trials have combined nettle leaf with diclofenac in arthritis, allowing a lower drug dose. Several Iranian RCTs between 2013 and 2016 reported that nettle leaf extract (typically 500 mg three times daily for 8–12 weeks) reduced fasting glucose and HbA1c in type 2 diabetes, but these were small single-center studies. Nutritional analyses confirm high calcium, iron, magnesium, and vitamin K content. Overall, the evidence is suggestive but preliminary for every indication.
Active Compounds
Flavonoids (quercetin, kaempferol, rutin), caffeic and chlorogenic acids, histamine and acetylcholine in the stinging hairs, chlorophyll, minerals (calcium, iron, silicon, potassium), vitamin K
Forms & Bioavailability
Minerals in nettle are reasonably well absorbed, with the exception that oxalate and fiber may reduce calcium and iron uptake somewhat; vitamin C in the leaf aids iron absorption. Flavonoids such as quercetin are modestly bioavailable. Freeze-drying preserves heat-sensitive compounds better than air-drying and is the form used in the allergy trial. Long steeping (10–15 minutes, or overnight cold infusion) extracts more minerals into tea.
Dosage Guidance
| Use Case | Dosage |
|---|---|
| Seasonal allergies | 300 mg freeze-dried leaf 2–3x daily |
| Osteoarthritis (oral) | 500 mg leaf extract 2–3x daily |
| Blood sugar support | 500 mg leaf extract 3x daily |
| Nutritive tea | 1–2 tbsp dried leaf per cup, steeped 10–15 min |
| Mild diuretic | 2–4 mL tincture 3x daily |
Always consult a healthcare provider for personalized dosing.
Natural Food Sources
- Cooked young nettle leaves (soup, sautéed like spinach — cooking removes the sting)
- Dried nettle leaf tea
- Nettle pesto, nettle cheese (Cornish Yarg), nettle beer
- Nettle leaf powder added to smoothies
Potential Side Effects
Mild stomach upset, sweating, skin irritation from fresh plant contact; rare allergic reaction; may lower blood sugar or blood pressure
Who Should Avoid It
- Warfarin therapy (vitamin K content can reduce anticoagulant effect — keep intake consistent and inform your doctor)
- Kidney disease or fluid/electrolyte disorders (diuretic effect)
- Diabetes or blood pressure medications without monitoring (additive effects)
- Pregnancy (traditional caution — may stimulate uterine contractions in some sources)
- Known allergy to nettle or Urticaceae plants
Pregnancy & Lactation
Views differ. Nettle leaf tea has a long tradition as a pregnancy and postpartum tonic for its iron and mineral content, yet some herbal authorities advise against medicinal doses in pregnancy because of possible uterine stimulation and lack of safety studies. Culinary amounts are considered safe. It is traditionally used to support milk supply during lactation, but evidence is anecdotal. Discuss use with a midwife or physician.
Known Drug Interactions
May add to diabetes medications, blood pressure drugs, and diuretics; high vitamin K content may reduce warfarin effect; may enhance sedatives and NSAIDs; theoretical lithium interaction via diuresis
Evidence Classification
Based on in vitro studies, animal models, pilot trials, or traditional use documentation. Clinical evidence is limited.
Frequently Asked Questions
What is the difference between nettle leaf and nettle root?
Nettle leaf (aerial parts) is used for allergies, inflammation, blood sugar, and as a nutritive tonic. Nettle root is a separate preparation studied for benign prostatic hyperplasia, where it affects sex hormone-binding globulin and prostate growth factors. The two are not interchangeable; check which part a product contains.
Does nettle really help hay fever?
The one controlled trial found a modest benefit, and the proposed mechanism (mild antihistamine and mast-cell stabilizing activity) is plausible, but the evidence is thin. Many people report relief, especially from freeze-dried leaf started before pollen season. It is reasonable to try but unlikely to replace antihistamines for moderate to severe symptoms.
Is it safe to eat nettles, and does cooking remove the sting?
Yes. Blanching, steaming, or drying collapses the stinging hairs and neutralizes the irritants, making nettles a delicious and nutritious green, similar to spinach. Harvest young leaves before flowering with gloves, as older plants develop gritty cystoliths and are less palatable.
Can nettle interfere with blood thinners?
Nettle leaf is rich in vitamin K, which counteracts warfarin. If you take warfarin, do not start or stop nettle without telling your clinician, and keep your intake consistent so your INR stays stable. Newer anticoagulants (DOACs) are not affected by vitamin K.
References
- Randomized, double-blind study of freeze-dried Urtica dioica in the treatment of allergic rhinitis. Mittman P. Planta Med (1990)View study
- Randomized controlled trial of nettle sting for treatment of base-of-thumb pain. Randall C, Randall H, Dobbs F, Hutton C, Sanders H. J R Soc Med (2000)View study
- Improved glycemic control in patients with advanced type 2 diabetes mellitus taking Urtica dioica leaf extract: a randomized double-blind placebo-controlled clinical trial. Kianbakht S, Khalighi-Sigaroodi F, Dabaghian FH. Clin Lab (2013)
- Stinging nettle. Examine.comView study
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This entry is for educational purposes only. It is not medical advice. Always consult a qualified healthcare provider before starting, stopping, or changing any supplement regimen, especially if you take medications or have health conditions.