Written by Julia Green, Alexander Kalisch and the CAM-Cancer Consortium.
Updated January 29, 2015

Milk thistle (Silybum marianum)

Abstract and key points

  • Milk thistle herbal preparations are produced from the seeds of Silybum marianum (L.) Gaertn.
  • Several potential uses of milk thistle in cancer are supported only by pre-clinical evidence
  • Milk thistle is generally considered safe

Milk thistle herbal products are made from seeds of Silybum marianum. Milk thistle has a long history of medicinal use. It is widely used to treat digestive and liver disorders. Claims in relation to cancer are that milk thistle prevents cancer initiation, reduces cancer development, reduces adverse effects of chemotherapy and radiotherapy, and supports the action of some anticancer drugs.

While numerous animal and in vitro models support these claims, they are not supported by data from clinical studies. Only one randomised pilot study is available which is merely showing a trend towards a reduction of hepatic toxicity.
Milk thistle is generally well tolerated and appears safe.

In summary, currently there is insufficient clinical evidence to support or refute the claims for milk thistle in relation to cancer management.

Read about the regulation, supervision and reimbursement of herbal medicine at NAFKAMs website CAM Regulation.


Julia Green, Alexander Kalisch, CAM-Cancer Consortium. Milk thistle (Silybum marianum) [online document]. http://cam-cancer.org/The-Summaries/Herbal-products/Milk-thistle-Silybum-marianum. January 29, 2015.

Document history

Assessed as up to date in January 2015 by Barbara Wider.
Summary first published in May 2013, authored by Julia Green and Alexander Kalisch.


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