Milkweed Plant Can Cause Serious Poisoning

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