Signs of cypermethrin toxicity include numbness, tingling, itching and burning sensations, loss of bladder control, lack of coordination, and seizures, according to Cornell University Cooperative Extension. Ingesting cypermethrin sometimes causes nausea, vomiting, diarrhea and convulsions.
Cypermethrin is a pesticide used to kill insects on fruit, vegetable and cotton crops, as well as in spot and crevice applications in homes and businesses. Another use is as a topical insect repellent on horses, states Cornell University Cooperative Extension. Mild exposure to the skin or eyes sometimes causes irritation, especially in people with an allergy to the chemical. Longer exposure or exposure to higher concentrations causes a variety of skin symptoms, including tingling and burning, and in some cases progresses to affecting the central nervous system. Ingestion requires immediate treatment and can be fatal.
Chronic cypermethrin exposure may lead to central nervous system problems and changes in other organs and tissues, according to Cornell Cooperative Extension. In studies using rabbits, repeat doses of cypermethrin led to changes in the liver, lungs, skin, adrenal glands and the cortex of the thymus. The Environmental Protection Agency lists cypermethrin as a weak carcinogen. Most of the available information on the long-term toxicity of the pesticide comes from animal studies. The human body rapidly metabolizes and excretes the chemical.