White Snakeroot Poisoning

Medically Reviewed by Mahammad Juber, MD on October 06, 2022
4 min read

There are an abundance of plant species out there, including some that are known and some that are not. In fact, there are over 300,000 known plant species, with more being discovered annually. 

With so many plants out there, though, it’s hard to keep track of them all and to know which ones are safe and which ones aren’t. Some are commonly known for being harmful, such as poison ivy and poison oak, while others may simply give you pause. 

Here, we will discuss the white snakeroot. 

White snakeroot (ageratina altissima) is a plant that can be found in the eastern United States, often in wooded areas. One state where white snakeroot is frequently found is Missouri, where it is often discovered in woodlands with trees and rocky terrains.

White snakeroot is a weed that grows throughout spring and summer, its white flowers blooming in fall. Typically a small, inconspicuous plant reaching anywhere from one to four feet tall, white snakeroot grows discreetly, spreading its dark and leafy greens around shaded areas until the fall, when its white flowers appear. Once it has bloomed, its seeds are carried away by the wind and planted in other places where the snakeroot will continue to spread. 

Bees, moths, and butterflies are particularly fond of white snakeroot since its white flowers provide them with plenty of nectar and pollen as the seasons change from summer to fall. Besides providing these insects with food, white snakeroot offers insects a place to mate. 

White snakeroot also has other benefits. Its roots can be brewed in tea and used to treat fever, diarrhea, or kidney stones. Another benefit of white snakeroot is its leaves, which can be used to treat snakebite wounds and wake people who have fainted, typically using the smoke of its burning leaves.  

However, white snakeroot has its disadvantages, too. 

White snakeroot displays compressed growth. Its branches lay low to the ground, and its leaves are short and broad. It usually sprouts around 12 to 25 white flowers per head when blooming. Leaves are typically flat and wrinkled. White snakeroot is traditionally found in dry areas with shade, rarely growing more than five feet tall. 

There are two types of white snakeroot: altissima and roanensis. The difference between these two varieties is in the shape of their flowerheads. Altissima has flowerheads that are not cusped and are 3 to 5 mm long, while roanensis has cusped flowerheads that are 4 to 7 mm long.

White snakeroot is toxic to livestock and also causes illness in humans who consume milk from affected animals. Animals who ingest this plant are prone to muscle necrosis, an infection of soft tissue, and cardiotoxicity, leading to heart damage. Since the poison is present in milk, animals who are still nursing can also contract the poison from their mother. 

Animals poisoned by white snakeroot show signs of it somewhere between a few days and a few weeks. Affected animals exhibit symptoms such as weight loss, constipation, foul-smelling breath and urine, trembling, listlessness, excessive salivation, and more. Sometimes, affected animals may experience terminal collapse. 

Both cattle and horses are prone to white snakeroot poisoning. Unfortunately, fatality among poisoned livestock is high.  

White snakeroot’s toxic agent is tremetone. Toxicity is more prevalent in green plants, but dried plants also remain toxic.

White snakeroot causes illness in humans who have consumed it, typically after consuming milk from an affected animal. The resulting illness, known as milk sickness, affected many people during the 18th and 19th centuries. 

The symptoms of milk sickness include: 

  • Weakness 
  • Loss of appetite
  • Abdominal pain
  • Vomiting
  • Constipation
  • Severe thirst
  • Tremors
  • Foul-smelling breath 
  • Delirium
  • Coma
  • Death

To prevent white snakeroot poisoning in livestock and humans, livestock should be kept away from areas where white snakeroot grows. 

If you suspect you have consumed affected milk and are worried about white snakeroot poisoning, you should contact the Poison Control Center for help. 

In livestock, treatment is focused on supportive care. You can ensure they have access to plenty of bedding to help prevent pressure sores. Poisoned livestock should also avoid exercise and excitement. If they are nursing, they should receive frequent milking, but their milk should be thrown away. 

Diagnosing white snakeroot poisoning is typically done on a symptom basis. Professionals observe clinical signs, muscle enzymes are tested, and the area might be checked for white snakeroot.

One plant that is commonly mistaken for white snakeroot is the late boneset. While these two may look similar from a distance, though, each is easily identifiable up close, especially if you know what to look for. 

Late bonesets are taller than white snakeroots, and their branches broadly spread out. Their leaves are long and narrow, unlike the white snakeroot’s short and wide leaves. They develop fewer flowers per head, typically around 9 to 14, and they can grow to be as tall as 6.5 feet. While white snakeroot is found in drier areas, late bonesets thrive in sunny, wet environments. 

Other similar species include: 

  • American boneset 
  • Tall thoroughwort 
  • Joe-pye weeds
  • Mist flower
  • Plainleaf pussytoes
  • American bugleweed

If you’re having trouble identifying white snakeroot, you can always use a plant identifying app, though it is still typically best to exercise caution before touching or consuming anything you find in nature.