Poison Hemlock Identification & Management

Poison-hemlock is acutely toxic to people and animals.  It is common on roadsides, in open fields, and in natural areas.


Poison-hemlock is acutely toxic to people and animals, with symptoms appearing 20 minutes to three hours after ingestion.  All parts of the plant are poisonous and even the dead canes remain toxic for up to three yearsThe amount of toxin varies and tends to be higher in sunny areas.  Eating the plant is the main danger, but it is also toxic to the skin and respiratory system.  When digging or mowing large amounts of poison-hemlock, wear gloves and a mask or take frequent breaks to avoid becoming ill.  On a hot day toxins can be absorbed into the skin and cause severe reactions.  The typical symptoms for humans include dilation of the pupils, dizziness, and trembling followed by slowing of the heartbeat, paralysis of the central nervous system, muscle paralysis, and death due to respiratory failure.  For animals symptoms include nervous trembling, salivation, lack of coordination, pupil dilation, rapid weak pulse, respiratory paralysis, coma, and sometimes death.  For both people and animals quick treatment can reverse the harm and typically there aren’t noticeable aftereffects. If you suspect poisoning from this plant, call for help immediately because the toxins are fast-acting – for people, call poison-control at 1-800-222-1222 or for animals, call your veterinarian.

Identification & Control

Poison Hemlock blooms in the late spring, so this is the time of year to identify it and remove it. Shown below is a very helpful fact sheet produced by King County, Washington. They have put together all of the information you need to get started in identifying, and controlling Poison Hemlock. PLEASE USE CAUTION WHEN HANDLING POISON HEMLOCK. IT CAN CAUSE ACUTE RESPIRATORY DISTRESS AND DEATH. King County has more in depth information at their website (http://www.kingcounty.gov/services/environment/animals-and-plants/noxious-weeds/weed-identification/poison-hemlock.aspx).

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