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MONKSHOOD - Aconitum species

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Distinguishing features

Monkshood is a perennial herb with tuberous fleshy roots and erect stout stems (0.5-1.5 meters tall). Leaves have 5-7 segments, deeply divided. Flowers are in dense racemes, violet-blue with helmet-shaped hoods.

DescriptionPerennial herbaceous plant with tall leafy stems that grow to one foot.  Leaves and flowers resemble larkspur (Delphinium) species but can be differentiated.  The stems of monkshood are not hollow like those of larkspur.  
Geographic rangeSeveral species grow in North America, generally in rich, moist soils along streams or in open woods.  At high altitude, monkshood often grows near larkspur species.
Toxic principleThe principle toxins found in monkshood are diterpene alkaloids of the aconitine type.  
ToxicityAll species of monkshood should be considered toxic to humans and animals.  All parts of the plant are toxic, especially the roots, seeds, and new leaves.  Horses have been fatally poisoned after consuming 0.075% of their body weight of the plant.  The alkaloids can be absorbed through the skin and may cause poisoning in humans handling the plant.
Mechanism of toxicologic damageAconitine-type diterpene alkaloids bind sodium channels, causing persistant activation.

Clinical signsClinical signs are similar to those caused by larkspur poisoning.  Within a few hours of ingestion, restlessness, and excessive salivation are seen.  Animals develop muscle weakness and hypotension and have difficulty breathing.  Eventually, affected animals will collapse in lateral recumbancy.  Death may occur several hours to days post-ingestion due to either heart block and ventricular fibrillation or to respiratory failure.  

LesionsNo lesions are seen.

TreatmentNo treatment has been proven effective in monkshood poisoning.  Affected animals should be stressed as little as possible. Symptomatic treatment with intravenous fluids may be helpful.  Vomiting and diarrhea should be controlled.  Oral activated charcoal and osmotic laxatives may be helpful to reduce absorption of alkaloids from the GI tract. 


Copyright 2002

University of Pennsylvania
Created by:    Alexander Chan (2003), Daphne Downs (2002), Chris Tsai (2001), Brett Begley (2000), Janet Triplett (1997)
Faculty Advisor:  Dr. Robert Poppenga