Euphorbia peplus (petty spurge,[1][2] radium weed,[2] cancer weed,[2] or milkweed),[2] is a species of Euphorbia, native to most of Europe, northern Africa and western Asia, where it typically grows in cultivated arable land, gardens and other disturbed land.

[1][3][4] Outside of its native range it is very widely naturalised and often invasive, including in Australia, New Zealand, North America and other countries in temperate and sub-tropical regions.

peplus),[5] predominantly countries on the north edge of the Mediterranean (PoWo Map) The plant's sap is toxic to rapidly replicating human tissue, and has long been used as a traditional remedy for common skin lesions.

A pharmaceutical-grade ingenol mebutate gel has approval from the US Food and Drug Administration for treatment of actinic keratosis.

[6][7][8] In Germany, recent studies have linked Euphorbia peplus with the virtual elimination of squamous cell skin cancer.