The Full Story
Cocklebur (Xanthium strumarium or Xanthium spinosum) plants grow prickly fruit (burrs) that are spread easily by clinging to clothing and fur. Although it is hard to believe, the unfriendly-looking cocklebur is related to the sunflower and the daisy! Fun fact: in 1941, a Swiss engineer named George de Mestral used a microscope to examine the burrs that had stuck to both him and his dog during a walk. He found that the spikes of the burrs had small hooked ends that allowed them to easily stick to other things. He copied the structure and, voilà, VELCRO® Brand fasteners were invented!
Each cocklebur burr contains two seeds, and these seeds look and taste similar to sunflower seeds. However, cocklebur seeds should NEVER be eaten! Cocklebur seeds contain a chemical called carboxyatractyloside, which can cause mild symptoms like unpleasant taste and nausea or more severe symptoms like abdominal pain, vomiting, low blood sugar, seizures, and severe liver injury. Mild symptoms typically occur before severe symptoms develop. It can take up to 3 days for symptoms to develop, and it can take up to 2 days for mild symptoms to resolve. Patients with severe symptoms should be evaluated by a medical professional.
It is thought that the plant and seeds are most toxic during the seedling stage and that their toxicity decreases as the plant gets older. Plants with four or more leaves are expected to contain less toxin, but mature cocklebur plants are still dangerous.
If someone has unintentionally swallowed cocklebur seeds, you can help them by doing the following:
- Gently wipe out their mouth.
- Have them rinse and spit with water to remove remaining plant material from their mouth.
- Eat a small meal as soon as possible.
- Call Poison Control or use the webPOISONCONTROL® online tool.
If burrs have stuck to your clothing, there are some simple ways to remove them. Soften the bristles of the burr by washing the clothing as you normally would. This makes it easier to break the hooked bristles on the burrs. You can then go over the cloth with a fine-tooth metal comb or a lint roller to remove the loosened burrs. You can also try scraping the cloth with a hard, straight-edged object like a credit card.
If you suspect someone has been exposed to cocklebur and is having a problem, check the webPOISONCONTROL® online tool for guidance or call Poison Control at 1-800-222-1222.
Lindsy Liu, PharmD
Certified Specialist in Poison Information
Gurley ES, Rahman M, Hossain MJ, Nahar N, Faiz MA, et al. Fatal outbreak from consuming Xanthium strumarium seedlings during time of food shortage in northeastern Bangladesh. PLoS One. 2010 Mar 18;5(3):e9756.
Karabiber H, Almis H, Selimoglu MA, Yakinci C, Yilmaz S. Xanthium strumarium poisoning requiring liver transplantation. J Pediatr Gastroenterol Nutr. 2014 Jan;58(1):e6-9.
Stuart BP, Cole RJ, Gosser HS. Cocklebur (Xanthium strumarium, L. var. strumarium) intoxication in swine: review and redefinition of the toxic principle. Vet Pathol. 1981 May;18(3):368-83.
Turgut M, Alhan CC, Gürgöze M, Kurt A, Doğan Y, et al. Carboxyatractyloside poisonings in humans. Ann Trop Pædiatr. 2005 Jun;25(2):125-34.
West PL, Mckeown NJ, Hendrickson RG. Muscle spasm associated with therapeutic use of Cang Er Zi Wan. Clin Toxicol (Phila). 2101;48(4):380-4.