Educational information, not medical advice — ask your doctor or midwife.
Rosin Weed is the root and sticky resin of Silphium laciniatum, a tall prairie plant in the daisy family. American folk and Eclectic healers used it mainly for coughs and as a bitter stomach tonic. Human evidence for any of those uses is essentially absent.
The plant is better known as Compass Plant. Its large, deeply cut leaves often line up north to south. Prairie travellers once used them to get their bearings.
Traditional use tells you that people valued a plant. It does not show that the plant works, and it does not show that it is safe. Read the claims on this page as history, not as proof.
The names overlap in a confusing way. "Rosinweed" is also used for other Silphium species, such as Silphium integrifolium. It is not milk thistle (Silybum marianum), and it is not the lost silphium of ancient Rome.
No one has shown how Rosin Weed acts in the human body. The honest answer is that it is not known.
The old reasoning was simple. The root is full of resin and bitter compounds. Bitters were thought to wake up digestion, and resins to loosen mucus in the chest.
Lab work on Silphium plants is thin. A few test-tube studies report that extracts slow some bacteria and mop up free radicals (unstable molecules that damage cells). Whether any of that happens in a person is unknown.
Many daisy-family plants contain sesquiterpene lactones (bitter plant chemicals). In cell studies these can act on inflammation pathways. They are also a common cause of skin rash in people who handle the plants.
Rosin Weed is a niche herb. Most shops and pharmacies do not stock it at all.
The dried, cut root is the usual form. Specialist herb suppliers sell it loose by weight.
Alcohol tinctures of the root are made by small herbalists. The hardened resin was chewed like gum in the past.
Always check the botanical name on a label. A product sold as "rosinweed" may be a different Silphium species. Capsules and lab-tested extracts are rare to non-existent.
Rosin Weed has a modest place in 19th-century American herbal writing. Eclectic physicians, who leaned on plant medicines, listed it among the cough and tonic herbs.
Plains peoples knew the plant well. The hardened resin was chewed, and parts of the plant were used in various household ways.
Eclectic texts such as King's American Dispensatory described the root as an expectorant (a cough remedy meant to loosen mucus). It was also called a bitter tonic for weak appetite. Some writers used it for intermittent fevers.
It was never a leading herb, even in its own era. Settlers and farriers also gave it to horses with breathing trouble. Use faded as the Eclectic schools closed in the early 20th century.
Stop taking it and get urgent help if you have swelling of the lips, face or tongue, hives, or trouble breathing. These can be signs of a serious allergic reaction.
Stop and see your doctor if you get a skin rash, lasting stomach pain, vomiting, or yellowing of the skin or eyes.
See a doctor rather than treating yourself if a cough lasts more than three weeks, if you cough up blood, if you are short of breath, or if a fever lasts more than three days.
In the United States it may be sold as a dietary supplement. It is not approved by the FDA to treat any illness.
In the UK and EU it is not an authorised traditional herbal medicine. The plant is also a native prairie species, and wild digging is restricted in some places.
Evidence grades and traditional-use labels are explained in our methodology. Nothing here is medical advice.
What it is typically used for, usual dose, cautions, and the study behind it where real trial data exists.
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