aconitine

Extremely poisonous alkaloid found in the plants aconite and larkspur. It has no smell but is very bitter and produces a tingling sensation when applied externally. If it is eaten or enters the body through a mucous membrane or a wound, it causes death by respiratory or heart failure.

For internal use it has been used in the form of tincture or extract, and was once employed as a sedative. For external use it was formed into ointments or liniments and was formerly used as a skin irritant in neuralgia. However, the active dose is so close to the fatal one that the alkaloid is no longer used. In cases of aconite poisoning the stomach must be immediately emptied and a doctor called.