Aconitine is a highly poisonous alkaloid derived from the aconite plant. It is a neurotoxin that opens TTX-sensitive Na+ channels in the heart and other tissues, and is used for creating models of cardiac arrhythmia.

Aconitine has the chemical formula C34H47NO11, and is soluble in chloroform or benzene, slightly in alcohol or ether, and practically not at all in water. It has an LD50 in mice (intravenously) of 0.12 mg/kg and in rats (orally) of 5.97 mg/kg.