Featured Poison

The Trouble with Thistles

People learn in different ways. Some learn by reading, others by observation, and then there are people like me that just need to pee on the electric fence themselves.*

* I don’t know who said this. It’s been attributed to Will Rogers, but his estate and museum say it’s not from him.

Where am I going with this? When writing I tend to gravitate towards things I can encounter or photograph on my own, like my back yard pokeweed or horseradish and how I nearly killed my dad, or have some type of personal connection with, like root beer and red tide. Things I can experience, like peeing on an electric fence. The problem with this is that it can make this site a bit Americancentric (I’m not positive that’s a real word, but I’m sure you understand). And while there’s nothing inherently wrong with that, I have a huge number of visitors and readers from outside North America. I like these people, they have great questions and comments, and I am asked often to write about poisons they could encounter, i.e. fences they could pee on. And the most vocal people so far have been Italian, and I’ve got a good one for them.

In the southern Italian region including the islands of Sardinia and Sicily, and surrounding Mediterranean areas, like Greece on the European side and Tunisia on the African, grows a humble thistle. Despite the painful lobed, prickly leaves and spike covered pink flowers, Atractylis gummifera is a visually appealing plant. Its rhizomes – underground stems that sends out roots and shoots (ex. culinary ginger) – can reach 15 inches in length and 3 inches wide, and its leaves exude a whitish latex when broken. Given its scientific name by the Godfather of modern taxonomy and botany, Carl Linnaeus himself, this thorny thistle has been known for thousands of years and gone by many names, such as Musciurda in Sardinia and Masticogna in Sicily.

Atractylis gummifera by Fotoculus (CC BY-NC-SA 20)

Atractylis gummifera by Fotoculus (CC BY-NC-SA 20)

Long before pharmaceutical companies like Bayer, Merck, and Pfizer came around, people turned to plants as a source of medicinal compounds – which is obvious to any reader of this site – and A. gummifera is no exception. For thousands of years native peoples have used root decoctions for just about everything: intestinal parasites, snake-bites, toothaches, even to remove freckles. I’m not sure how well it worked, however, as there are poisonings still today, most resulting in death.

In Greece, a 7-year old boy was given an extract of A. gummifera as a traditional medicine to treat a pinworm infection. Two days later he was admitted to the hospital with upper abdominal pain, vomiting, and generally disorientated and unresponsive. Shortly, he was placed on a mechanical ventilator and diagnosed with cerebral edema (excessive fluid in and around the brain). Two days later he was in a coma, jaundiced, and despite supportive care, died 8 days after admittance. Liver failure was obvious from the jaundice, but autopsy confirmed it by revealing hepatic necrosis. (1)

Untitled presentation (1)

The question we are left with is “Why?” What type of poison can cause this much damage and devastation? The answer is atractyloside (ATR), a diterpenoid glycoside stored in the rhizomes, and first isolated in 1868. (A glycoside is just a molecule attached to a sugar, a previous example is oleandrin.) Atractyloside acts as an inhibitor of oxidative phosphorylation, which is a mouthful to say, but pretty important. Oxidative phosphorylation is the process by which aerobic organisms – those that require oxygen to live, like us – convert food and nutrients into energy, in the form of adenosine triphosphate (ATP). Specifically, ATR inhibits the transport of ATP intermediate adenosine diphosphate (ADP) within the mitochondria of our cells, preventing the synthesis of ATP. Without our “molecular currency of energy” ATP, our cells are starved of energy and move onto Plan B, breakdown of glycogen. Our bodies then tear apart liver and muscle tissue to convert glycogen to glucose, leading to an initial phase of hyperglycemia (high blood sugar). But when our cells are also starved of oxygen, like in the case of an ATR-poisoned patient, anaerobic glycolysis sets in, and converts glucose to lactate, leading to a state of hypoglycemia (low blood sugar) and lactic acidosis. This is bad. Symptoms of severe lactic acidosis are abdominal pain, nausea, vomiting, generalized weakness, and tachypnea (a funny word meaning rapid breathing), and can be deadly.

So to sum it all up: liver failure, kidney failure, hypoglycemia, lactic acidosis – take your pick, they all can be fatal, either quickly from a hypoglycemic coma or slowly from liver failure. With multiple modalities of death, survival rates are low, and average around 15%**. From a clinical standpoint, and besides being an emergency physicians worst nightmare, there’s no treatment for A. gummifera poisonings other than supportive care. All that can be done is treat the symptoms: replace fluids, control seizures, and give cardiovascular and respiratory support.

** Most surivival rates of I’ve read are in the 10-15% range, some have been higher. I suspect a lot has to do with location, and access to and quality of emergency medicine.

While most poisonings are accidental, and the result of mistaking A. gummifera for another thistle or wild artichoke, or from using a “traditional remedy,” there are hints that it has been used for more nefarious reasons….murder. While I haven’t been able to track down anything concrete, it does make sense. The rhizome of A. gummifera is readily available, sweet tasting (as opposed to bitter alkaloids, like strychnine), symptoms of poisoning are not immediate and it could take days until the victim seeks help, and death is fairly certain, at about 85%. So while homicidal poisonings in general are rare, it is certainly both plausible and possible….but please, don’t try this at home.

** Homepage featured image by Luis Nunes Alberto (CC BY-SA 3.0) **


  1. Georgiou, M., L. Sianidou, T. Hatzis, J. Papadatos, and A. Koutselinis. “Hepatotoxicity Due to Atractylis Gummifera-L.” Journal of Toxicology: Clinical Toxicology 26.7 (1988): 487-93.
  2. General reading:
    1. Stewart, Michael J., and Vanessa Steenkamp. “The Biochemistry and Toxicity of Atractyloside: A Review.” Therapeutic Drug Monitoring 22.6 (2000): 641-49.
    2. Daniele, C., S. Dahamna, O. Firuzi, N. Sekfali, L. Saso, and G. Mazzanti. “Atractylis Gummifera L. Poisoning: An Ethnopharmacological Review.” Journal of Ethnopharmacology 97.2 (2005): 175-81.
    3. Obatomi, D.K, and Bach, P.H . “Biochemistry and Toxicology of the Diterpenoid Glycoside Atractyloside.” Food and Chemical Toxicology 36.4 (1998): 335-46.


10 thoughts on “The Trouble with Thistles

  1. Should I be concerned that my wife has a thing for pointing out every thistle that we see?

    (I missed reading these in the morning. Glad to have you back)

  2. Should I be concerned that my wife has a thing for pointing out every thistle that we come across?

    (I missed reading your posts in the morning, glad to have you back)

  3. Great to see you back – as good as ever. These mini-articles would combine to make a fascinating little book. Meanwhile I,m popping them into my card index of poisons.

  4. Great to have you writing again, Justin. As usual, a Ph.D., while helpful, is not requisite.

  5. Your highly vocal reader from Italy has much enjoyed your article on “cardi” (this is the Italian translation for thistles, coming down directly from classical Latin “carduus” and late imperial Latin “cardum”). I didn’t know all these fascinating details about sweet homicidal poisonings. Many thanks.

  6. It is true that Carlina gummifera is very similar but does not really belong to the Carduus genus, but colleagues living in Sicily told me yesterday accidents are not unknown of there because of confusion. Many thanks.

  7. I have only just found your blog and it saddens me to see it in it’s seeming death throes… but I have to say reading through these have been so interesting and wonderfully written! Thank you for being you and giving me something fun to read whilst I work my way back through your postings!
    Sam (UK)

  8. Pingback: Are Thistle Flowers Poisonous? - Essential Garden Guide

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