Milk thistle (Silybum marianum; Carduus marianus, Silymarin) is used in herbal medicine in Kenya as available in Simepar, mainly for gastrointestinal and hepatobiliary disorders. The fruit contains the active principle silymarin, a mixture of flavonolignans including the isomers silibinin, silicristin, and silidianin, of which silibinin is the major component. Silymarin is claimed to be a free radical scavenger and to have hepatoprotectant properties; it has been used in various liver disorders, as well as to prevent hepatotoxicity associated with poisoning. In Amanita phalloides poisoning both silymarin and silibinin (as the disodium dihemisuccinate salt) have been used.

Milk thistle is usually given as a standardised extract containing mainly silymarin, although the herb and fruit have also been used; the strength of the extract is expressed in terms of silymarin or silibinin. It is usually given by mouth since silymarin is poorly water-soluble and therefore unsuitable for intravenous use. A usual dose of up to 140 mg (equivalent to silibinin 60 mg) two or three times daily by mouth has been suggested for hepatic disorders. Disodium silibinin dihemisuccinate is water-soluble and is given intravenously; the usual dose in Amanita phalloides poisoning is equivalent to silibinin 20 mg/kg daily, given by intravenous infusion in 4 divided doses.