Scary moment for restoration crew serves as a timely reminder about risks of poison-hemlock

Even an experienced restoration crew following all the safety precautions can be at risk when working around poison-hemlock. By being aware and responding quickly, Nellie Hannah, Forterra’s WCC crew supervisor, and her team of AmeriCorps members are all fully recovered from a recent noxious weed removal project, but it’s scary how things might have gone if they had acted differently. The bottom line of the story is this: if you are pulling poison-hemlock, always listen to your body, take a break if things don’t feel right, and take your buddies with you!

Poison-hemlock grows in dense patches so make sure to take breaks for fresh air when removing it, and always wear gloves!

We first heard from Nellie when she called our program to ask about poison-hemlock symptoms. Ben Peterson, who answered the call, realized her concern was for people currently feeling sick so he gave her the number for Poison Control (1-800-222-1222). When Ben checked back later to make sure everyone was o.k., Nellie agreed to share her story so we could alert other people working around poison-hemlock. In her own words, here is what happened:

Thanks for checking in! My crew is thankfully fully recovered! It was definitely odd, as I’ve controlled poison hemlock (including that same site) for a few years and have never had a reaction like this.

We were hand pulling a dense patch of first year rosettes in Tacoma. It was located under a healthy stand of willows and dogwood. In terms of PPE we had lined rubber gloves, long sleeves, and raingear on.

We had spent 3 or 4 hours in that area (with a half hour break in the middle) when we realized that four of our six crew members had some degree of lightheadedness/dizziness and nausea. Two of us were also feeling a little confused.

We left the area, took vitals, and looked up the symptoms of hemlock poisoning before calling our sponsor and then Ben, who directed us to call the poison control center.

Poison control seems to have heard of a case like this where there was too much handpulling and told us about life-threat symptoms to look out for (tremors, vomiting, severe drowsiness, etc.) within the 1st hour after leaving the area.

Luckily we all felt better after a few hours of being away from the patch! It was pretty wet in there so we’re wondering if maybe the sap leached through our glove cuffs, or if we weren’t getting enough air circulation and some chemical compound was volatilizing. I know we’ve been cautioned to not mow through patches, especially in hot weather, for that reason.

AmeriCorps members
AmeriCorps members serving with Forterra’s WCC crew. Photo by Nellie Hannah.

Poison-hemlock is an acute nerve toxin so symptoms usually appear soon after exposure, which mainly occurs through ingesting the plant but can happen through other means like breathing in particles or even through the skin in some cases. People respond differently, but dizziness and nausea are good indicators that you should take a break.

According to the literature (which is somewhat scary I will admit!), the typical symptoms for people 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.

Fortunately, it is unusual for people to become ill when simply controlling poison-hemlock, and symptoms like Nellie’s crew experienced are temporary if you move to fresh air when you start to feel sick. As Nellie said, she had controlled poison-hemlock many times without any ill effects, even in the same location. This time they had bad luck probably due to the poor air circulation, but fortunately they did everything right. They paid attention to how they were feeling, got away from the plants and called Poison Control. Good work Nellie and crew!

shovel digging up poison-hemlock plant
Young poison-hemlock plants can be removed with a shovel.
poison-hemlock plant in gloved hands
Poison-hemlock can be controlled by digging it up, just make sure to wear gloves.
poison-hemlock leaves
Poison-hemlock leaves are divided into lacy-looking segments with toothed edges.
poison-hemlock stem
Poison-hemlock stems have reddish-purple spots or blotches.
poison-hemlock plant
Taller stems of poison-hemlock stems often have a whitish coating as well as reddish-purple spots.
Flowering poison-hemlock plant
Poison-hemlock has small white flower clusters on the ends of branched stems and can grow 4 to 8 feet tall.

For more information about poison-hemlock:

Poison-hemlock (Conium maculatum) April 2018 Weed of the Month

Poison-hemlock control now required on public lands and roads in King County (and Weeds of Concern list grows by two)

Poison-hemlock identification and control


  1. Glad to hear everyone is safe and that the location will be safer for future visitors!

  2. How common is poison hemlock? I don’t think I have seen it before, but could be very wrong.

    • It is pretty widespread, at least in King County WA, but we are trying to make it less so! It is more conspicuous in the spring and early summer when the plants are taller.

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