# Is this a common reaction to this thistle? **URL:** \ **Category:** Factual Questions\ **Created:** [June 22, 2009, 3:49pm UTC](https://boards.straightdope.com/t/is-this-a-common-reaction-to-this-thistle/500594 "2009-06-22T15:49:54Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![Amazon\_Floozy\_Goddess](https://avatars.discourse-cdn.com/v4/letter/a/779978/32.png) [@Amazon\_Floozy\_Goddess](https://boards.straightdope.com/u/Amazon_Floozy_Goddess)\ **Post date:** [June 22, 2009, 3:49pm UTC](https://boards.straightdope.com/t/is-this-a-common-reaction-to-this-thistle/500594/1 "2009-06-22T15:49:54Z")
I live in Ontario Canada, where the annual Spiny Sow Thistle is a common ground weed. It has long, flat leaves covered in fine spines. Ever since I can remember, if I happen to brush past one and the spines prick me, the area immediately flares up in an angry, agonizing, burning rash, sometimes accompanied by hives. It takes several minutes to subside and is sometimes tender for awhile afterwards. Is this a common reaction to contact with this thistle’s spines, something that happens to anyone who gets pricked, or does it sound like an allergy? I already have allergies since one year of age (Oak, Elm, Birch trees; Timothy and Red Top grasses; mold; ragweed), but nothing I’m allergic to causes a topical reaction like this. ---
**Author:** ![Amazon\_Floozy\_Goddess](https://avatars.discourse-cdn.com/v4/letter/a/779978/32.png) [@Amazon\_Floozy\_Goddess](https://boards.straightdope.com/u/Amazon_Floozy_Goddess)\ **Post date:** [June 23, 2009, 1:09pm UTC](https://boards.straightdope.com/t/is-this-a-common-reaction-to-this-thistle/500594/2 "2009-06-23T13:09:25Z")
Bump. ---
**Author:** ![Qadgop\_the\_Mercotan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/qadgop_the_mercotan/32/83_2.png) [@Qadgop\_the\_Mercotan](https://boards.straightdope.com/u/Qadgop_the_Mercotan)\ **Post date:** [June 23, 2009, 1:23pm UTC](https://boards.straightdope.com/t/is-this-a-common-reaction-to-this-thistle/500594/3 "2009-06-23T13:23:12Z")
Use of Google Scholar on “sowthistle” and “dermatitis” yields no pertinent references that I could find on sowthistle causing a dermatitis. Sounds like an uncommon reaction. ---
**Author:** ![Shagnasty](https://avatars.discourse-cdn.com/v4/letter/s/9dc877/32.png) [@Shagnasty](https://boards.straightdope.com/u/Shagnasty)\ **Post date:** [June 23, 2009, 1:43pm UTC](https://boards.straightdope.com/t/is-this-a-common-reaction-to-this-thistle/500594/4 "2009-06-23T13:43:09Z")
They are edible so I would say no. However, certain kinds of nettles cause that same reaction but that applies to almost anyone. Folk wisdom says to pee on the affected body part right away but that is much harder for females than males. It seems to help for me out least. It also works for jellyfish stings but just don’t do it next to someones picnic basket. ---
**Author:** ![Harmonious\_Discord](https://avatars.discourse-cdn.com/v4/letter/h/74df32/32.png) [@Harmonious\_Discord](https://boards.straightdope.com/u/Harmonious_Discord)\ **Post date:** [June 23, 2009, 1:56pm UTC](https://boards.straightdope.com/t/is-this-a-common-reaction-to-this-thistle/500594/5 "2009-06-23T13:56:16Z")
I’ve never heard of a rash inducing chemical being a trait of the spiny sowthistle. I think you must be allergic. ---
**Author:** ![Broomstick](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/broomstick/32/246_2.png) [@Broomstick](https://boards.straightdope.com/u/Broomstick)\ **Post date:** [June 27, 2009, 11:49pm UTC](https://boards.straightdope.com/t/is-this-a-common-reaction-to-this-thistle/500594/6 "2009-06-27T23:49:48Z")
There are a couple species of thistle whose spines cause irritation, even burning, that can last awhile. However, the hives you get, as well as the rashes, would seem to indicate to me (though I am not a doctor, just allergic to stuff) that you’re having an allergic reaction of some sort, in addition to the discomfort everyone else feels. ---
**Author:** ![Fetchund](https://avatars.discourse-cdn.com/v4/letter/f/b2d939/32.png) [@Fetchund](https://boards.straightdope.com/u/Fetchund)\ **Post date:** [June 28, 2009, 3:04am UTC](https://boards.straightdope.com/t/is-this-a-common-reaction-to-this-thistle/500594/7 "2009-06-28T03:04:50Z")
Have you tried any experiments? Like, making sure that it is the Sow Thistle that is causing the reaction… Around here, our Sow thistle and Stinging Nettle grow in the exact same kinds of environments - often the Thistle is hiding nettles underneath. Rude, if you ask me. Same goes for Poison Ivy, which is almost ALWAYS intertwined with wild grape or Virginia Creeper vines.