Milk Thistle: Benefits and Side Effects

Milk thistle (silymarin) is a flowering herb related to the daisy and ragweed family. It is native to Mediterranean countries. Some people also call it Mary thistle and holy thistle.

What Is Milk Thistle Used For?

Milk thistle is sometimes used as a natural treatment for liver problems. These liver problems include cirrhosis, jaundice, hepatitis, and gallbladder disorders.

Some claim milk thistle may also:



Does Milk Thistle Work?

Silymarin is the main active ingredient in milk thistle. Silymarin is both an anti-inflammatory and antioxidant. It’s unclear what benefits, if any, this may have in the body.

Is Milk Thistle Good for the Liver?

At this point, there is not enough scientific data to say whether or not milk thistle can help liver problems. Some early research suggests milk thistle may aid people with alcohol-related liver disease. Other studies show no improvement in liver function in this group of people.

Some studies also show milk thistle may offer a possible benefit for people whose liver is damaged by industrial toxins, such as toluene and xylene.

More information is needed before doctors can say milk thistle actually benefits the liver.

Can Milk Thistle Help People With Diabetes?

Medical research does suggest that milk thistle, combined with traditional treatment, can improve diabetes. Studies have shown a decrease in blood sugar levels and an improvement in cholesterol in people with type 2 diabetes.

Researchers also have found that milk thistle improved insulin resistance, a key characteristic of type 2 diabetes.

Diabetes is a serious condition. Talk to your doctor before taking any supplements, as they may interfere with your medication.

Is Milk Thistle Good for the Heart?

By lowering LDL "bad" cholesterol levels, milk thistle may help decrease the chance of developing heart disease. However, studies on possible heart benefits only have been done in people with diabetes. People with diabetes often have high cholesterol. It’s unclear if milk thistle may have the same effects in other people.

Milk thistle can also be taken in conjunction with cholesterol lowering medications, like statins. It can help prevent elevation of liver enzymes, which can be a side effect of the medication.


How Do You Take Milk Thistle?

Milk thistle can be taken orally in supplements or in tea. Milk thistle can be combined with other herbs.

Does Milk Thistle Have Any Side Effects?

Usually, milk thistle causes few, if any, serious side effects. Studies show that it’s safe when taken for up to 41 months.

Milk thistle may cause diarrhea. More rarely, it may cause nausea, bloating, gas, and upset stomach.

Women who are breastfeeding or pregnant should avoid using milk thistle.

If you have a ragweed allergy, you should also avoid milk thistle. Milk thistle may cause a rash or lead to severe allergic reaction.

Since milk thistle may mimic the effects of estrogen, some women should avoid this herb. This includes women who have fibroid tumors or endometriosis. Additionally, women with breast, uterine, and ovarian cancers should not take milk thistle.

Always tell your doctor of any supplement you are taking. Milk thistle may interact with certain medications.

WebMD Medical Reference Reviewed by Suzanne R. Steinbaum, MD on January 23, 2017


Natural Medicines Comprehensive Database: "Milk Thistle Monograph."
National Center of Complementary and Alternative Medicine (NCCAM): "Milk Thistle." "Generic Name: Milk Thistle – Oral."

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