In the United States, Senecio vulgaris has been listed as a noxious weed, being both non-native to most if not all of the Americas and having a reputation for being hepatotoxic to livestock and to humans.

Human As a plant that is reported to be both poisonous for humans and also medicinal, much of the contradiction can be found by closely reviewing the words that are used and the dose (amount) of the poisonous substance that is ingested to prove either claim. All species of the genus Senecio contain pyrrolizidine alkaloids (e.g., senecionine), a substance that when a human has chronic exposure can cause irreversible liver damage. Common groundsel as a medicinal herb does not seem to have been recommended very often since 1931, when it was recommended as a diaphoretic, an antiscorbutic, a purgative, a diuretic and an anthelmintic, which was a demotion as it was previously suggested for the expelling of gravel of the kidneys and reins by Pedanius Dioscorides in the 1st century, for use as poultices by John Gerard in the late 16th century and as a cure for epilepsy by Nicholas Culpeper in the 17th century. More current information is contradictory about the dangers of the ingestion of groundsel. A heavily referenced paper from 1989 suggests that the response is immediate and gives pre-ambulatory care recommendations. A Canadian poisonous plants information database references a paper from 1990 in presenting this prenatal warning: "In a case of prenatal exposure, a mother ingested tea containing an estimated 0.343 milligram of senecionine, resulting in fatal veno-occlusive disease in a newborn infant." Information about the pyrrolizidine alkaloids, the substance present in S.