Milk thistle is a popular herbal remedy that has been used for hundreds of years to treat a variety of medical conditions, including diseases of the liver and gallbladder (1).

More recently milk thistle has been promoted as a tool for encouraging weight loss, but scientific evidence to support this use is limited.

This article reviews what milk thistle is and whether it’s beneficial for weight loss.

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Milk thistle, also known as Silybum marianum and St. Mary’s thistle, is an herb that belongs to the Asteraceae family of flowering plants. It grows wild in sunny regions all over the world, including Europe, Africa, and Asia (2).

Milk thistle is characterized by its tall and slender stem, bright purple flowers, spiny green leaves, and sharp thorns.

It has been used in traditional herbal medicine for centuries and contains a variety of compounds with anti-inflammatory and antioxidant properties. These compounds are collectively referred to as silymarin, but the most potent one is known as silybin or silibinin (1).

The terms silymarin and silybin are often used interchangeably, though they technically refer to distinct chemical components of the milk thistle plant.

Modern research on the medicinal effects of milk thistle is limited and largely inconclusive (3).

The majority of available studies focuses on milk thistle’s potential to treat liver disorders, such as cirrhosis and fatty liver disease. It has also been studied as a potential treatment for high blood sugar among those with type 2 diabetes.


Milk thistle is a type of flowering plant that’s frequently used to treat diseases of the liver in herbal medicine practices.

Milk thistle is sometimes used to promote weight loss, but there’s very little research to support its ability to enhance fat loss or improve body composition.

One recent study evaluated the effects of using milk thistle extract on mice with obesity. Despite consuming similar quantities of food, the mice that received milk thistle lost about 5% of their weight, while the control group continued gaining weight throughout the study (4).

A handful of small human studies have evaluated milk thistle’s effects on certain metabolic symptoms associated with obesity, such as insulin resistance and inflammation, but none have looked specifically at milk thistle’s ability to promote fat loss (5).

Although the results are promising, a single animal study does not constitute enough evidence to reliably determine whether milk thistle can aid weight loss in humans.

More research is needed.


One study found that milk thistle encouraged fat loss in mice with obesity. However, more research is needed to determine whether similar effects could occur in humans.

Milk thistle is typically taken by mouth in capsule or extract form.

Current evidence suggests that dosages as high as 420 mg 3 times per day are likely safe for most people (6).

Although milk thistle has a decent record of safety, it isn’t completely risk-free.

The most commonly reported side effects include digestive disturbances, such as mild diarrhea and nausea. Allergic reactions to milk thistle may also include headache, itching, and joint pain (6).

People who are allergic to plants closely related to milk thistle, such as ragweed, daisies, and marigolds, may be at a greater risk of experiencing adverse reactions (3).

Milk thistle is not recommended for people who are pregnant or breastfeeding due to a lack of robust safety data (3).

There’s not currently enough evidence available to assess whether milk thistle may interact negatively with prescription medications. If you’re taking any medications, consult your healthcare provider prior to adding milk thistle to your wellness regimen.


Milk thistle is generally considered safe for most people at dosages up to 420 mg 3 times a day. However, it may cause allergic reactions, such as itching, headaches, and joint pain, or gastrointestinal symptoms like nausea or diarrhea.

Milk thistle is a popular herbal remedy that has been used for its therapeutic effects for centuries.

It contains a variety of antioxidant compounds that have been studied as a possible treatment for liver disease and type 2 diabetes.

Recently, milk thistle has been touted as a tool for promoting weight loss, but the evidence supporting this use is limited to one animal study.

At this point, there’s not enough evidence to indicate milk thistle has any weight loss benefits for humans.

Milk thistle is likely safe to consume but can cause allergic reactions in some people.

Consult your healthcare provider prior to adding milk thistle to your health and wellness routine.