Milk Thistle Print Page

Common Names: Lady’s Thistle, Marian Thistle, St Mary’s Thistle, silymarin
Scientific Names: Silybum marianum

Bottom Line

Effectiveness: Milk thistle is not recommended as there are no studies to support its use for rheumatologic conditions.
Safety: Likely safe if used orally and appropriately for up to 3 years.

What is Milk Thistle?

  • Milk Thistle is a plant. It gets its name from the milky sap that comes out of the leaves when broken.
  • The seeds and leaves are used to make medicine.


What it is it used for in people with rheumatic conditions?

  • Milk Thistle is not used to treat rheumatic conditions.
  • It could possibly be used to prevent liver toxicity from medicines such as methotrexate.


How is it thought to work?

  • Milk Thistle seeds contain the chemical silymarin, which is thought to protect liver cells.
  • Silymarin may reduce inflammation and act as an antioxidant.


Does it Work? What the Science Says:

  • There are no studies on the effects of milk thistle on rheumatic conditions.
  • There are no studies on the potential of milk thistle to prevent liver damage in patients taking medicines such as methotrexate.
  • Studies done in patients with liver damage called cirrhosis have not shown benefit.


What are possible side effects and what can I do about them?

  • Milk thistle is usually well tolerated when taken orally. The most common side effect is diarrhea.
  • Other less common side effects include nausea, heart burn, gas, bloating, and poor appetite.
  • Some people may be allergic to milk thistle and could get an itchy rash, eczema or even shortness of breath. If you are allergic to ragweed, chrysanthemums, marigolds, or daisies you should not use milk thistle.


With drugs:

  • Milk thistle may lower blood sugar levels. Patients with diabetes should monitor levels more closely.
  • Milk thistle may inhibit liver enzymes that metabolize other medications (CYP 2C9, 2D6, 3A4- moderate interaction). Consult your pharmacist before using milk thistle.

With Other Herbals:

  • Milk thistle may lower blood sugar levels. Do not use with other natural health products that may also lower blood glucose
    • Such as: chromium, devil’s claw, fenugreek, Panax ginseng, psyllium and others

With Other Diseases:

  • Milk thistle may lower blood glucose. Patients with diabetes should monitor levels more closely.


For more information about Milk Thistle, consult your physician and pharmacist.

What is Rheumatology?

Rheumatologists see over 100 different types of diseases. We are known for seeing arthritis, however, we also see many other conditions.

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