While stinging nettle may sound like a dangerous plant, it has many health benefits. It can reduce inflammation, help reduce allergies, treat arthritis, and increase testosterone. Although it is considered safe, stinging nettles has its risks and side effects as well. Keep reading to learn some surprising benefits and risks of stinging nettle use.
What is Stinging Nettle?
Stinging nettle (Urtica dioica) is an herb native to parts of Europe, Africa, Asia, and North America. Civilizations as old as Ancient Greece used this plant for its medicinal properties, though our modern names for it come from the Anglo-Saxon “noedl” (needle) and the Latin “urtica” (to burn) [R, R].
Stinging nettle has been used as a food, fabric, medicine, and cosmetics for thousands of years. Its wide array of uses includes everything from enhancing male health to easing nasal congestion [R, R].
Touching the leaves of a wild stinging nettle can cause skin irritation. However, when processed for consumption, the nettle’s stinging hairs are crushed, cooked, or boiled in a way that eliminates their stinging abilities and makes them safe for consumption [R].
Snapshot of Stinging Nettle
- Reduces inflammation
- Relieves allergies
- Reduces arthritis pain
- May increase free testosterone
- May relieve benign prostatic hyperplasia
- May decrease blood pressure and blood sugar
- Acts as a diuretic
- May improve wound healing
- Increases effectiveness of NSAIDs
- Stinging spines may cause a rash
- Rare allergic reactions to raw juice or purée
- May have dangerous drug interactions
- May worsen conditions with too much testosterone
Bioactive Compounds of Leaves
Stinging nettle contains multiple bioactive compounds responsible for its health and antioxidant effects. These include [R]:
- Quercetin, an antioxidant and anti-diabetic compound [R, R]
- Rutin, closely related to quercetin [R]
- Kaempferol, a potent anti-inflammatory compound [R]
- Quinic acid, an antioxidant and anti-inflammatory compound [R]
- Caffeic acid, another strong antioxidant [R]
- Choline, a vital nutrient with anti-inflammatory properties [R]
- Lecithin, a healthy fat that may help reduce cholesterol [R]
Bioactive Compounds of Root
Stinging nettle root has a significantly different chemical profile than the leaves, with about half the quinic acid and almost no caffeic acid by comparison. However, the roots also contain some compounds not found in the leaves, such as fatty acids, plant sterols, secoisolariciresinol, vanillin, and scopoletin [R, R, R].
Fresh stinging nettle plants contains many valuable vitamins and nutrients, including provitamin A, vitamin B1, vitamin K, potassium, calcium, and iron. It also contains oxalates, which will bind to these minerals and reduce their absorption [R].
Mechanism of Action
Stinging nettle is an antioxidant: it blocks the oxidation of fats, linoleic acid, deoxyribose, and muscle proteins, thereby protecting many tissues from oxidative stress [R].
Stinging nettle reduces inflammatory cytokine release and reduces inflammatory biomarkers like TNF-a, IL-1, IL-6, and hs-CRP. It also interferes with the way the body sends pain signals and decreases the sensation of pain [R, R, R, R].
These anti-inflammatory effects appear to also help allergies, reduce nasal congestion, help with arthritis, and more [R].
Why Touching a Wild Nettle Hurts
If you see a stinging nettle plant growing wild, don’t touch it without gloves! Nettle leaves and stems are covered with tiny, stinging hairs called trichomes, which will pierce your skin and inject an irritating fluid containing formic acid, histamine, acetylcholine, and serotonin. Histamine is an inflammatory compound that will make your skin red and irritated, and formic acid is the chemical that causes pain from ant and bee stings [R].
Proper preparation of stinging nettle leaves deactivates the formic acid. A high-quality stinging nettle leaf product will not contain anywhere near enough formic acid to cause concern [R].
Health Benefits of Stinging Nettle
1) Reduces Inflammation
In a study of 37 arthritis patients, combining stinging nettle tea with diclofenac (an anti-inflammatory drug) enhanced the drug’s anti-inflammatory effects [R].
2) Relieves Allergies
However, stinging nettle also contains histamine – especially the leaves and hairs. More research is required to fully understand how this plant can reduce mast cell activation despite containing histamine. Many of its other bioactive compounds likely act together to achieve an altogether allergy-relieving effect [R, R].
In one study, 57% of patients were said to have rated nettle as ‘effective’ in helping allergies, with 48% even saying nettle was more effective than allergy medications they had used previously [R].
3) Helps Relieve Arthritis and Pain
Stinging nettle’s anti-inflammatory properties also help relieve arthritis symptoms. A combination of stinging nettle leaf extract and devil’s claw significantly reduced symptoms of arthritis compared to a placebo in a 12-week study of 92 arthritis patients [R].
These arthritis-relieving properties may be due to nettle’s ability to inhibit the activation of a protein called NF-κB, which would otherwise increase the production of inflammatory compounds. NF-κB is often overactive in people with arthritis [R, R].
Urtication, also known as ‘flogging with nettles,’ is a technique where users apply raw, unprocessed stinging nettle leaves or stems to the body to generate inflammation. This has been used since Ancient Roman times for relieving chronic rheumatism [R].
There is also evidence that using stinging nettle leaves topically can help relieve pain in those with:
4) May Increase Free Testosterone
Free testosterone is the available blood testosterone, not bound to sex hormone binding globulin, or SHBG. The less testosterone that’s bound to SHBG, the more free testosterone is available for the body to use. Testosterone bound to SHBG is unusable to the body [R].
Stinging nettle roots contain substances called ligans, which bind to SHBG. This reduces the amount of SHBG that can bind testosterone; hence, while nettle does not increase total testosterone in the blood, it does increase available testosterone. Bodybuilders have traditionally used similar plant substances to increase free testosterone [R, R, R].
There is also evidence that stinging nettle blocks the conversion of testosterone into estrogen, an effect that is increased by adding saw palmetto. This combination acts on an enzyme called aromatase that converts testosterone to estrogen, but does not affect testosterone receptors [R].
5) May Reduce Benign Prostatic Hyperplasia
Benign prostatic hyperplasia (BPH) is a condition wherein the prostate gland becomes enlarged, usually due to age. This can cause difficulty urinating and various other symptoms, including sexual dysfunction [R, R].
A review of several studies showed that stinging nettle root extract effectively improves the symptoms of an enlarged prostate, with a low risk of negative effects or toxicity [R].
In a study of 246 BPH patients, a special extract of stinging nettle safely and effectively reduced the adverse effects of prostate enlargement when compared to placebo [R].
In another 6-month study of 558 people, stinging nettle roots significantly improved multiple measures of prostate health, including [R]:
- Relief of lower urinary tract
- Maximum urinary flow rate
- Residual urine volume
- Prostate size
- International Prostate Symptom Score
Another study combined stinging nettle and saw palmetto extract. It was as effective as and better tolerated than the prescription drug finasteride, which is used to treat enlarged prostates [R].
Note that stinging nettle root is significantly more effective than leaf or stem in people with BPH. This is probably due to their high lignan content, which the leaves don’t contain.
6) May Decrease Blood Sugar
In a study of 92 subjects, stinging nettle extract decreased fasting blood sugar levels and other blood sugar levels when compared with the placebo [R].
7) May Reduce Blood Pressure
Stinging nettle stems and leaves may reduce blood pressure, but they could also increase the risk of blood pressure dropping too low. In rats, stinging nettle lowered blood pressure by increasing the amount of salt that the kidneys filtered out of the blood [R].
8) Acts as a Diuretic
Diuretics, sometimes called water pills, are medications that increase urine production. They can help remove excess sodium and water from the body. Stinging nettle leaves and stems seem to increase urine flow and act as a diuretic [R, R].
- Decreasing blood pressure
- Compensating for poor kidney function
- Reducing bloating
9) May Improve Healing
In rats, stinging nettle leaf extracts improved the quality of healing of second-degree burns in rats when applied to their skin. It accelerated healing and reduced scarring more effectively than conventional methods (vaseline and silver sulfadiazine) [R].
Safety & Side Effects
Although certain applications require the leaves to be applied directly to the skin, we do not recommend touching a wild stinging nettle with your bare hands. The formic acid and histamine in the sharp “hairs” on the nettle’s surface will likely cause a red, lumpy rash. In addition, some people may experience an allergic reaction to raw puréed nettle or to nettle juice [R].
Due to possible contractions of the uterus, stinging nettle may be unsafe to take during pregnancy. Contractions of the uterus can cause a miscarriage or cause women to go into early labor [R].
Stinging nettle may increase free testosterone and may, therefore, worsen any health conditions caused by too much testosterone, such as polycystic ovarian syndrome (PCOS) [R].
Limitations and Caveats
Although there is a large body of promising research, caution should always be used when extrapolated the results of animal studies to humans. Also, as with any supplement, care should be used in taking it.
A few studies have demonstrated that different parts of the stinging nettle plant contain different chemical compounds and may have completely different effects. Some research that claims that nettle extracts either do or do not have certain benefits may not have investigated each part of the plant, each extract, or even the ideal extract for the job.
The active compounds in stinging nettle may block metabolic enzymes in the CYP1A family, thereby increasing the effects of any drugs broken down by these enzymes. In rats, this effect has been demonstrated with melatonin; other drugs that may be affected include caffeine, warfarin, and many others [R, R].
Talk to your doctor before combining stinging nettle with medication.
Forms of Supplementation
Stinging nettle is usually available in the following forms:
- Capsules (leaf or root extract)
- Tinctures (extract dissolved in alcohol)
- Loose leaves
- Dried roots
- Cream or gel (for arthritis and pain)
If collected and processed carefully, wild stinging nettle can also be gathered and cooked into many recipes. Look for instructions from experts before attempting to harvest nettle yourself.
Note that stinging nettle root is best for benign prostatic hyperplasia, while the leaves and leaf extracts are best for most other complaints. Always check the label to make sure you’re buying a product with the correct part of the plant for best effect.
A dosage of 450 mg of dry stinging nettle root extract per day is associated with beneficial effects for benign prostatic hyperplasia. Many commercial root supplements come in 250 mg or 500 mg capsules [R].
Increasing free testosterone is dose-dependent. A root tincture with a concentration of 0.6 mg/ml significantly blocked testosterone binding to SHBG; at a concentration of 10 mg/ml, binding was inhibited completely [R].
Commercial leaf extracts recommend between 275 mg and 2 g of their product per day; note that the quality and content of these extracts is likely variable. Raw stinging nettle leaf, cut from the live plant, significantly reduces pain when applied to directly to an arthritic joint for thirty seconds, once per day [R].
Some people report increases in clarity, enhanced focus, and more vivid dreams.
People say that stinging nettle significantly helps with seasonal allergies. Some users have been taking it for over 10 years.
One user stated that it gave him stronger erections and loads of confidence by increasing free testosterone levels. However, there is only anecdotal evidence available regarding sexual function.
Other users praised stinging nettle for helping with hair growth, eczema, and gingivitis, but no clinical evidence is available for these benefits.
Some people claim to experience no health benefits at all from using stinging nettle supplements.
Buy Stinging Nettle
- Capsules (Amazon or iHerb)
- Liquid Extract (Amazon or iHerb)
- Organic Tea (Amazon or iHerb)
- Loose Leaves (Amazon or iHerb)
Stinging nettle is a common plant that grows all over the world. People have used it to treat rheumatism and pain for thousands of years, and more recent research shows that it may reduce inflammation, relieve allergies, increase free testosterone, reduce blood sugar and pressure, act as a diuretic, and improve wound healing.
It is generally considered safe, though the fresh leaves and stem of the plant can cause a nasty, stinging rash when touched. True allergy to stinging nettle is rare, but possible. This supplement may increase the effect of NSAIDs and other drugs; caution is advised when combining stinging nettle with medication.
Stinging nettle is available in many forms, including loose leaf, capsules, tincture, root, tea, cream, or live (often wild) plant. Researchers do not agree on an effective dosage for all people, conditions, or parts of the plant.