Allergic reactions to fresh stinging nettle are common, but reactions to dried stinging nettle taken orally are more rare. To reduce the risk of allergic reactions, consult your physician before taking herbal supplements and never take more than the recommended amount. Do not give stinging nettle supplements to children because of a lack of research on proper dosing, according to the University of Maryland Medical Center.
Stinging nettle (Urtica dioica L.) grows wild in forests, fields and near woodlands in many parts of the U.S. It often grows in patches and may reach 3 feet high or taller. It has deeply toothed leaves and fine hairs that release histamines and formic acid when touched; these substances are similar to the compounds released by bees or fire ants, according to Purdue University. Brushing against stinging nettle can cause a mild to moderate rash, depending on the individual.
The same compounds that cause skin irritation can reduce inflammation and pain when used medicinally. Stinging nettle was used as a diuretic and to treat joint pain in medieval Europe. Today, it is used dried in capsules, teas and tinctures to treat arthritis, hay fever, gout, eczema and many other ailments.
Stinging nettle is a relatively mild, safe herb, but it may occasionally cause side effects or allergic reactions when taken orally. Symptoms include upset stomach, fluid retention and hives or a rash. Consult a doctor if you exhibit signs of an allergic reaction to stinging nettle and seek immediate medical help if you experience wheezing, difficulty breathing or swelling in the face and tongue.
Reactions to the Plant
Most people who come into contact with a live stinging nettle plant will experience an allergic reaction. Remove your shoes and clothing, and wash the affected area with warm soap and water to remove the fine hairs from your skin. Apply an anti-itch lotion and take an over-the-counter antihistamine. Seek medical attention, though, if the rash is severe or if you experience other symptoms, such as wheezing and difficulty breathing. Wear long pants and closed-toe shoes when walking in the woods or other areas where stinging nettle may grow. Wear gloves when handling stinging nettle and remove and launder all clothing promptly.
Herbs are not regulated by the Food and Drug Administration and may vary in their potency. Consult a doctor before using stinging nettle or any other herbal supplement. Stinging nettle, in addition to possibly causing an allergic reaction, may interact with other drugs, particularly drugs that treat high blood pressure, diabetes or arthritis, according to the University of Maryland Medical Center.