Poison Hemlock: What Parents Should Know

Poison hemlock is a highly invasive, flowering plant commonly found in central and western Ohio. This widespread plant can be toxic, even in small amounts when ingested by people, livestock, and wildlife. Ingestion of the plant is generally rare since the plant does not have a pleasant taste or smell, with less than 150 ingestions reported to Ohio Poison Centers since 2015.

How to Identify

Poison hemlock is part of the carrot (Apiaceae) family, grows up to 10 feet tall and is often found on roadsides, open fields, and alongside fencing. Mature poison hemlock features small white flowers arranged in umbrella-like clusters on ends of branched stems and is often confused with wild carrot (commonly referred to as Queen Anne’s Lace). One distinguishable feature of the poison hemlock is the smooth, red/purple-spotted stems. Wild carrot has hairy stems that lack red splotches.

Dangers

All parts of the poison hemlock plant contain the poisonous alkaloid coniine, a compound similar to nicotine. Symptoms of coniine ingestion include nausea, vomiting, abdominal pain, burning or irritation of the mouth and throat, excessive salivation, confusion, dilation of the pupils, double vision, headache, and dizziness. In severe cases, patients may develop tremor, kidney failure, seizure, difficulty breathing and muscle paralysis. The severity of toxicity depends on the amount of coniine ingested, which depends on the season, geographic location and changes in temperature.

Ingestion of poison hemlock is the biggest concern, but extensive inhalation or skin contact can lead to toxicity. To minimize exposure, protective measures such as gloves and masks should be used if pulling or mowing poison hemlock. If you suspect someone was exposed to this plant, call your local poison control (1-800-222-1222) for guidance. For animal exposures, call your veterinarian.