Stinging nettle is a prolific perennial plant that has hairs called trichomes lining its leaves and stems. As a defense strategy, these hairs act like tiny needles to inject chemicals into invading pests and predators -- or your legs as you walk by. The result is an inflammatory reaction accompanied by temporary paresthesia, characterized by a burning or a "pins and needles" sensation. This explains why the plant has earned several descriptive common names, such as burn weed and burn hazel. No matter what you prefer to call it, a brush with the plant will likely be memorably unpleasant. There are simple remedies for nettle stings.
Stinging nettle, or Urtica dioica, has been used as food and medicine for centuries. Today, the plant's chemical compounds are under investigation as potential therapeutic agents to treat enlarged prostate, high blood pressure and a variety of inflammatory disorders, such as arthritis, allergies and eczema. The chemicals found in the stinging hairs of nettle responsible for the pharmacological effects of the plant are histamine, acetylcholine, various leukotrienes and formic acid, the same agent found in bee venom. When these chemicals penetrate the skin after contact with the plant, the local allergic reaction is referred to as urticaria.
Soap and Water
Washing the affected area with cool water and a mild soap usually brings relief from nettle stings. If soap is not available, splashing the area with plain water will suffice. If water is not available at all, consider using your own saliva to cleanse the area until you can get to soap and water.
Many topical treatments are reputed to counter the negative effects of nettle stings that range from centuries-old folk remedies to modern over-the-counter preparations. One immediate solution is to apply the juice of the leaves of certain plants that may be neighboring the nettle, such as broad leaf plantain or dock leaf. Alternatively, applying the spores from the underside of the fern is supposed to stop the burn and itch. If botanical identification is not your forte, try spreading mud over the area instead. Other topical remedies include a paste of baking soda and water, calamine lotion and milk of magnesia.
Remedies that act as histamine antagonists, or antihistamines may help to counter nettle stings. Internally, antihistamine medications block histamine from binding to histamine receptors in mast cells in the skin, which prevents an inflammatory reaction from the immune system. Topical corticosteroid preparations such as hydrocortisone creams or sprays are available over-the-counter or by prescription.
Rarely, some people may experience a severe systemic or body-wide allergic reaction evidenced by hives or rash, difficulty breathing, dizziness and swelling of the tongue, which warrants immediate medical attention. This is particularly important for people who have a known allergy to bee venom since stinging nettle and certain species of bees produce formic acid as a defense mechanism. Left untreated, a severe inflammatory reaction could lead to anaphylaxis, which can be fatal.