They have short half-lives and do not present a persistent danger to the environment. They act by activating sodium channels, prolonging the channel's activated state, and enhancing sodium influx. They may also produce counter-irritant like sensations with dermal exposure. If death occurs in acute toxicity it is usually by respiratory arrest. Anaphylactic reactions may also occur, due to the fact that these are natural products and may be recognised as antigenic substances.
Treatment is primarily supportive and symptomatic.
An added complication of pyrethroid toxicity is the addition of piperonyl butoxide to many products. This agent increases the absorption of the insecticide in both insects and mammals. It possesses toxicity independent of the insecticide, producing convulsions and coma. These are broad-leaf herbicides used to control weed growth in corn, grain, sorghum, pastures, and rangeland. In mammals they exert CNS stimulatory activity similar to some insecticides.