Milkweed Plant Can Cause Serious Poisoning

milkweed monarch butterfly on flower

The Bottom Line

Milkweed grows throughout the US and is essential for the survival of monarch butterflies. All parts of the plant contain toxic cardiac glycosides, which can cause nausea, vomiting, diarrhea, weakness, and heart rhythm changes. Milkweed can also irritate the skin and eyes if touched.

child holding dried milkweed

What is milkweed?

The Asclepias genus is a group of perennial flowering herbs known as milkweed due to their milky sap. There are over 200 species in the Asclepias genus that are native to Africa, North America, and South America. The plant is most easily identified by its distinctive pod-like fruit containing densely packed seeds. When the fruit pods mature and turn brown, they burst and release the seeds. 

Is milkweed toxic?

All parts of milkweed plants contain toxic cardiac glycosides. The highest concentrations of cardiac glycosides are found in the plant's latex fluid, followed by the stems, leaves, and roots. The plant is most toxic just before it reaches maturity. Cardiac glycosides have narrow therapeutic windows, meaning small changes in dosage can result in large differences in toxicity.

Symptoms of milkweed toxicity

When milkweed is swallowed, symptoms of toxicity usually appear within a few hours. Initial symptoms consist of stomach upset, nausea, vomiting, abdominal pain, diarrhea, weakness, lethargy, and confusion. Symptoms of severe toxicity include seizures, heart rhythm changes, and severe slowing of the heart rate. Milkweed is potentially poisonous to animals as well as to humans. After grazing on milkweed in a field, sheep can develop difficulty walking, seizures, and death. 

Effects on skin and in eyes

Milkweed sap can also cause skin and eye irritation. If your skin comes into contact with milkweed sap, you should immediately wash the affected area thoroughly with soap and water. If someone experiences eye irritation after getting sap in their eye, gently rinse the eye with room-temperature water for 10–15 minutes. If there is any persistent skin or eye pain, seek medical examination and treatment.

Can milkweed be beneficial?

Milkweed is very beneficial…if you are a monarch butterfly. Monarch butterflies cannot survive without milkweed; their caterpillars only eat milkweed plants, and adult monarchs need milkweed to lay their eggs. The butterflies absorb enough of the cardiac glycosides in milkweed to make them toxic to predatory birds, which quickly learn that monarch butterflies do not make a good meal.

Even though milkweed is recognized as a poisonous plant, there are multiple websites that provide recipes for the preparation of fried milkweed pods, milkweed shoots, and milkweed elixir. Some of those websites state that the cardiac glycosides present in milkweed are water soluble, making milkweed safe to eat if cooked properly. However, there is no evidence that this is correct. Eating milkweed, even when it is cooked or boiled, is not recommended and is potentially very dangerous.

Is milkweed dangerous to plant?

Due to loss of habitat, the population of monarch butterflies is rapidly declining. Many groups and communities encourage the planting of milkweed to feed migrating monarchs. Since contact with the sap can be irritating, you should wear disposable gloves when handling the plants.

What should you do if you experience milkweed toxicity 

If you suspect someone has been exposed to milkweed and is having a problem, check the webPOISONCONTROL online tool for guidance or call Poison Control at 1-800-222-1222.

Diana Pei, PharmD
Certified Specialist in Poison Information

Revised William G. Troutman, PharmD
Professor of Pharmacy Emeritus

Poisoned?

Call 1-800-222-1222 or

HELP ME online

Prevention Tips

  • Have all your plants (indoor and outdoor) correctly identified by a knowledgeable expert.
  • Keep all plants out of the reach of children and pets.
  • Do not prepare your own herbal medicines.
  • Do not prepare food or tea from plants unless you are an expert and know how to do so safely.
  • Wear gloves when handling milkweed plants.

This Really Happened

Case 1. A 46-year-old woman placed cut milkweed into a jar of water. She eventually removed the milkweed from the jar but forgot to dump out the water. She later drank from the jar. She took a dose of Pepto-Bismol before calling Poison Control. Her only complaint was a bad taste in her mouth. Poison Control instructed her to drink water to help with the taste. Poison Control followed up with her 3½ hours later, and she did not have any symptoms.

Case 2. A 12-year-old boy ate a piece of a milkweed plant at school. He liked its taste, so he took 2 more bites. The school's assistant principal called Poison Control about an hour after the ingestion, at which time the boy did not have any symptoms. Poison Control instructed the assistant principal to continue to monitor the boy for symptoms, although severe symptoms were not expected from this small exposure. Poison Control called the school the next day and learned that the boy never developed symptoms.


For More Information

Taylor D. Plant of the week: common milkweed (Ascepias syriaca L.). US Forest Service. Accessed June 30, 2025.

Native milkweeds. Xerces Society. Accessed June 30, 2025.


References

Clark JG. Whorled milkweed poisoning. Vet Hum Toxicol. 1979;21(6):431.

Hack JB. Cardioactive steroids. In: Nelson LS, Howland MA, Lewin NA, Smith SW, Goldfrank L, Hoffman RS, eds. Goldfrank's Toxicologic Emergencies. 11th ed. McGraw Hill Education; 2019.

Nelson CJ, Seiber JN, Brower LP. Seasonal and intraplant variation of cardenolide content in the California milkweed, Asclepias eriocarpa, and implications for plant defense. J Chem Ecol. 1981;7(6):981-1010.

Save the monarch. US Fish & Wildlife Service. Accessed July 1, 2025.

Shanahan KM, Thomas MA, Walker EN, Downs JW. Forage and you shall find: cardiac glycoside poisoning and the danger of foraging. Mil Med. 2023;188(7-8):e2812-e2815.

Simpson NS, Cole JB, Ellsworth H. What toxicity may result from ingestion of the plant pictured below? Answer: cardioactive steroid toxicity from common milkweed. J Med Toxicol. 2013;9(3):287-288.

Smith RA, Scharko P, Bolin D, Hong CB. Intoxication of sheep exposed to ozark milkweed (Asclepias viridis Walter). Vet Hum Toxicol. 2000;42(6):349-350.

Venkateswaran N, Tonk RS, Berrocal A. Corneal edema in a gardener. JAMA Ophthalmol. 2020;138(9):998-999.

Poisoned?

Call 1-800-222-1222 or

HELP ME online

Prevention Tips

  • Have all your plants (indoor and outdoor) correctly identified by a knowledgeable expert.
  • Keep all plants out of the reach of children and pets.
  • Do not prepare your own herbal medicines.
  • Do not prepare food or tea from plants unless you are an expert and know how to do so safely.
  • Wear gloves when handling milkweed plants.

This Really Happened

Case 1. A 46-year-old woman placed cut milkweed into a jar of water. She eventually removed the milkweed from the jar but forgot to dump out the water. She later drank from the jar. She took a dose of Pepto-Bismol before calling Poison Control. Her only complaint was a bad taste in her mouth. Poison Control instructed her to drink water to help with the taste. Poison Control followed up with her 3½ hours later, and she did not have any symptoms.

Case 2. A 12-year-old boy ate a piece of a milkweed plant at school. He liked its taste, so he took 2 more bites. The school's assistant principal called Poison Control about an hour after the ingestion, at which time the boy did not have any symptoms. Poison Control instructed the assistant principal to continue to monitor the boy for symptoms, although severe symptoms were not expected from this small exposure. Poison Control called the school the next day and learned that the boy never developed symptoms.