05/29/2026
🌱Poison Hemlock (Conium maculatum) is a non-native invasive species which grows in local ditches, roadsides, fencerows, floodplains, meadows and fields.
This is one of the most toxic plants in North America, and ALL parts of it contain a toxin deadly to humans and livestock. Poisoning can occur through ingestion, inhalation, or absorption via the eyes and broken skin. Poison hemlock rarely causes a severe skin rash, but the sap is highly dangerous if it enters the bloodstream through minor skin cuts, scratches, or abrasions.
⚠️ How Toxicity Progresses (Rapid Onset)
Early Signs (First 15 mins to 2 hours):
Nausea, vomiting, and dizziness
Restlessness/confusion or visible muscle twitching
Muscle weakness and muscle twitches, tremors
Rapid heart rate and sweating
Dilated pupils
Excess salivation or dry mouth
High blood pressure
🚨 Late/Severe Signs (Critical Danger):
Slow heartbeat
Low blood pressure
Kidney failure
Extreme muscle weakness or paralysis starting in the legs
Seizures or loss of consciousness
Suffocation: Total paralysis of the breathing muscles (diaphragm), which stops the lungs from working.
🏥 THE TREATMENT:
There is NO ANTIDOTE for poison hemlock. If you suspect someone has ingested this plant, swallowed sap, or inhaled debris, CALL 911 IMMEDIATELY. Do not induce vomiting. You may call Poison Control (1-800-222-1222) right away if the person has no symptoms. Hospital treatment requires emergency supportive care, including mechanical ventilation (breathing machines) and IV fluids.
🛑 LANDOWNER SAFETY TIPS:
1. NEVER burn poison hemlock. The smoke carries the toxins and can paralyze your lungs if inhaled.
2. NEVER weed-whack or openly mow the plants. This sends toxic sap into the air and into your eyes/lungs. Only mow if using heavy commercial equipment with fully enclosed, shrouded decks. When mowing, personal protection equipment (PPE) must be used.
3. ALWAYS wear heavy gloves, long sleeves, and eye protection if removing it by hand-digging.
Note: Cutting poison hemlock after it starts blooming can actually cause its seeds to finish maturing and spread across your property.
Be safe, know what's growing in your yard, and share this to protect your neighbors!
ℹ️ Helpful links:
How to recognize the plant: https://bygl.osu.edu/node/2614
Poison control: https://www.poison.org/articles/can-poison-hemlock-be-deadly-184
Medical information: https://my.clevelandclinic.org/health/diseases/24122-poison-hemlock
For livestock owners: https://www.ars.usda.gov/pacific-west-area/logan-ut/poisonous-plant-research/docs/poison-hemlock-conium-maculatum/