Nettle Stinging (Urtication): A Scientific Look
How the sting of fresh nettle works on the skin, what research says about its use for leg and joint pain, how it is applied and who should avoid it.
Introduction
In traditional medicine, stinging nettle (Urtica dioica) is considered a plant with a hot and dry temperament (in the second or third degree). It is described as a strong natural aid for dispelling coldness, loosening thick humours and removing excess moisture from the body. Modern phytochemistry has also shown that its leaves and roots are rich in biologically active compounds: vitamins A, C, K and B; minerals such as iron, calcium, magnesium and silicon; strong antioxidants; flavonoids (especially quercetin) and a range of phenolic compounds.
But nettle’s value is not limited to food or herbal remedies. One of the most interesting methods in old medical practice is applying the fresh plant directly to the skin. In modern terms this is called urtication (nettle stinging).
Lightly striking the feet, knees or joints with a bunch of fresh nettles may at first look uncomfortable or even painful. Yet research in physiology and neuroscience has begun to explain the biochemical and nerve mechanisms behind this old method and how it can affect the legs.
In this article we look in detail at what actually happens when fresh nettle touches the skin of the legs and feet, and what the evidence says.
The mechanism: what happens when nettle touches the skin
The leaves and stems of nettle are covered in thousands of microscopic, needle-like hairs (trichomes) with tips made of silica. They behave like tiny ampoules that can inject their contents just under the skin.
When the plant brushes or is tapped against the skin, these fine glass-like tips break off and release a chemical mixture into the skin. Its main components are:
- Histamine: mainly responsible for redness, warmth and widening of the blood vessels.
- Serotonin and acetylcholine: stimulate nerve endings and contribute to the burning, stinging feeling.
- Formic acid: also found in ant venom, it creates a controlled, local inflammatory response.
- Leukotrienes: biological mediators that help the vessel-widening effect last longer.
Effects of nettle stinging on the legs and feet
These simultaneous reactions can affect muscles, connective tissue, joints and the nervous system.
1. Reducing chronic pain through substance P depletion
One of the most discussed mechanisms concerns substance P, a neuropeptide that carries pain signals from damaged joints and muscles to the central nervous system.
The intense stimulation caused by nettle makes nerve endings release their stores of substance P quickly. Once these stores are used up, the nerve fibres concerned are thought to transmit pain signals less effectively for a while, from a few hours to a few days.
A similar mechanism is used in pain creams containing capsaicin.
2. Gate control theory of pain
According to the gate control theory, the nervous system cannot process all incoming sensory signals with equal intensity at the same time. The sudden, superficial burning caused by nettle may suppress pain pathways at the level of the spinal cord and so reduce the perception of deeper, chronic pain.
This is why it has been tried for:
- Pain from knee osteoarthritis
- Sciatic pain
- Chronic muscle and tendon pain
3. Strong local increase in circulation (vasodilation)
The feet and calves are among the parts of the body furthest from the heart, so poor circulation and poor venous return are more common there. Through the action of histamine:
- Capillaries widen
- Local blood flow increases noticeably
- Delivery of oxygen and nutrients speeds up
Possible results include:
- Less chronic coldness: people whose feet always feel cold may notice a temporary rise in warmth.
- Support for tissue repair: more blood reaching joints, ligaments and tendons may support healing.
- Clearing metabolic waste: lactic acid and other by-products in the muscles may be cleared more easily through the circulation.
4. Immune stimulation and secondary anti-inflammatory effects
The mild local inflammation caused by nettle is treated by the body as a tiny injury (microtrauma). In response it sends white blood cells, macrophages, tissue-repair proteins and natural anti-inflammatory factors. It is thought this response may help damp down some chronic inflammatory processes.
Which leg and foot problems may benefit most
Osteoarthritis and joint pain
In a small randomised controlled trial (Randall and colleagues, 2000), people with pain at the base of the thumb or index finger who applied fresh nettle leaf to the painful area had lower pain scores than those who used a placebo leaf. Smaller exploratory reports describe similar experiences with knee and other joint pain, and some people say they need fewer anti-inflammatory painkillers such as ibuprofen or diclofenac. Larger studies are still needed.
Sciatica and nerve pain
Light application along the path of the sciatic nerve (back of the thigh, calf and ankle) has been used traditionally for shooting, electric-like pain, tingling and numbness.
Chronic coldness and weak circulation
In people with a cold temperament or weak circulation in the limbs, nettle stinging can have a strong warming effect.
Calf cramps
By increasing circulation, it may help ease calf cramps, especially at night.
Correct and safe method
The method used in studies is gentle, not harsh or traumatic:
- Wear thick protective gloves to hold the fresh nettle stems.
- The plant must be fresh; dried nettle has lost most of its active stinging hairs.
- Gently brush or very lightly tap the leaves on the painful area (for example around the knee, the thigh or the calf) for about 30 to 60 seconds.
- Redness, burning and small hive-like bumps appear quickly.
- Pain relief usually begins once the first burning sensation fades, about 15 to 30 minutes later.
- The relief can last from a few hours to a few days.
Try a small patch first to see how your skin reacts.
Contraindications and cautions
This method is not suitable for everyone. Do not use it in the following situations.
Open wounds and skin conditions
Do not apply it to cuts, wounds, eczema or psoriasis. It can cause severe irritation, secondary infection or excessive inflammation.
Diabetic neuropathy
People with nerve damage from diabetes may feel less pain, which raises the risk of skin damage, excessive inflammation and tissue injury.
Advanced vascular disease
Get a doctor’s opinion first if you have:
- Severe varicose veins
- Deep vein thrombosis (DVT)
- Peripheral arterial disease
- Advanced atherosclerosis
Strong stimulation of the circulation may be risky for some people.
Strong allergic tendency
Take great care if you have had a serious allergic reaction to bee stings, ant or insect stings, or a strong reaction to histamine. Rarely, systemic reactions, shortness of breath and serious allergic reactions can occur. Seek emergency help if you have trouble breathing, swelling of the face or throat, or widespread hives.
Conclusion
Nettle stinging has been used in folk medicine for centuries. Research in neuroscience, physiology and phytotherapy suggests it is more than a traditional belief: it may work through measurable mechanisms such as reducing pain signalling, widening blood vessels, increasing circulation and stimulating the immune response.
It can be considered as a supportive method for knee and other joint pain, sciatic pain, chronic coldness and some musculoskeletal complaints. However, people with serious vascular disease, diabetic neuropathy or a strong allergic tendency should not try it without medical advice.
References
- Randall C, Randall H, Dobbs F, Hutton C, Sanders H. Randomized controlled trial of nettle sting for treatment of base-of-thumb pain. Journal of the Royal Society of Medicine. 2000;93(6):305-309.
- Chrubasik JE, Roufogalis BD, Wagner H, Chrubasik S. A comprehensive review on the stinging nettle effect and efficacy profiles. Part II: Urticae radix. Phytomedicine. 2007;14(7-8):568-579.
- Upton R. Stinging nettles leaf (Urtica dioica L.): Extraordinary vegetable medicine. Journal of Herbal Pharmacotherapy. 2013;13(1):9-38.
- Bone K, Mills S. Principles and Practice of Phytotherapy: Modern Herbal Medicine. 2nd ed. Edinburgh: Churchill Livingstone; 2013.
- Yarnell E. Botanical medicines for the urinary tract. World Journal of Urology. 2002;20(5):285-293.
Whether this method suits you depends on your temperament and circulation. You can take our free temperament test to learn your own temperament.
This article is for information only and is based on traditional medical sources and general health knowledge. It is not a medical diagnosis, treatment or prescription and does not replace an examination by a doctor. If you have a health complaint, take regular medication, are pregnant, or are considering this for a child, consult your doctor before applying anything. Herbal products can interact with medicines.
