Herb library · Herb · Asclepias tuberosa
Pleurisy root (butterfly weed)
The root of the orange-flowered butterfly weed, a milkweed, once a favorite 19th-century American remedy for chest colds and pleurisy. It has never been studied as a medicine. Like other milkweeds it contains cardiac glycosides, heart-active compounds; its sap has injured people's eyes.
Serious warning
The plant contains cardiac glycosides. In two reported cases, sap from butterfly weed reached people's eyes after they handled the plant and caused corneal swelling; one woman's sight fell to seeing only movement before steroid medicines brought it back. A forager who ate pods of a related milkweed developed a slow heart rate with a measurable digoxin-like level.
Traditional use
Eclectic physicians called pleurisy root one of their most common native medicines, giving the root to bring on sweating in fevers and to loosen phlegm in pleurisy, bronchitis and pneumonia. Its name comes from that use.
What studies show
- Insufficient
Coughs, pleurisy and fever: no studies of the root in people were found. The only studies of this plant in people are reports of harm from its sap (below).
Be careful of
Cautions
- InteractionBecause it contains heart-active glycosides, do not combine it with heart medicines such as digoxin.
- NoteWear gloves when handling the plant, and do not touch your eyes. Eye pain, haze or blurred vision after contact needs an eye examination the same day; say you handled milkweed.
- PregnancyDo not use it in pregnancy or while breastfeeding; no safety information was found.
- Ask a clinicianTalk with a clinician or pharmacist before using this if you take prescription medicines, are pregnant or breastfeeding, or are giving it to a child.
From the old books
What herbals and dispensaries of the past printed. History, in their words.
“Asclepias, or pleurisy root, was one of the most common of the indigenous medicines employed by the Eclectic fathers. It was favorably written upon by most of the earlier writers on American medicinal plants.”
Sources
- Corneal toxicity following exposure to Asclepias tuberosa (Open Ophthalmol J, 2017) — PubMed record (opens in a new tab) · NIH · read September 25, 2026
- Toxic keratoconjunctivitis from milkweed (Asclepias tuberosa) exposure in a contact lens wearer (J Emerg Med, 2026) — PubMed record (opens in a new tab) · NIH · read September 25, 2026
- Forage and you shall find: cardiac glycoside poisoning and the danger of foraging (Mil Med, 2023) — PubMed record (opens in a new tab) · NIH · read September 25, 2026
Reviewed September 25, 2026.