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Milk Thistle - Composition, Uses, and Side Effects

Published on Aug 02, 2022   -  4 min read


Milk thistle is an age-old herbal remedy for treating abdominal problems. Read the article below to know its details.

What Is Milk Thistle?

After its religious significance, the milk thistle is called Mary thistle or Holy thistle. Scientifically, it is called Silybum marianam. It has prickly leaves with white veins on them and purple flowers. It was used by ancient Greeks as a herbal remedy to treat abdominal issues related to the liver, kidney, and gallbladder. Due to these benefits, several scientific studies have been carried out, but the results of human studies are mixed. The mainly used active ingredient of milk thistle is silymarin, obtained from the plant's seeds. It is being widely used in the pharmaceutical industry as a supplement for treating various ailments. It is commercially modified as standardized preparations containing 70 % to 80 % ingredients, marketed as oral capsules, tablets, and liquid extract.

What Does Milk Thistle Comprise?

Silymarin – the active ingredient in milk thistle contains many flavonoids like silibinin, silydianin, and silicristin, and their flavonoid precursor, taxifolin; which have been claimed to reverse the damage to hepatic cells caused by alcohol, drugs, medications and other toxic substances. Silymarin also has a protective effect on liver cells, particularly the new ones, preventing their destruction. In addition, it is claimed to possess antioxidant, antiviral, and anti-inflammatory properties; that is why it is specifically used to cure cirrhosis, jaundice, hepatitis, and gallbladder diseases.

What Is Milk Thistle Used For?

Milk thistle has been known to have a myriad of health benefits. Due to this, the different parts of the plant are used for various purposes. Therefore, its health benefits are as follows:

  • Improves Liver Health: Silymarin in milk thistle decreases the production of free radicals and serves as an antioxidant. This helps in liver detoxification and enhances its functioning and overall health.

  • Assists in Skin Health: Milk thistle has antioxidant, anti-inflammatory, and anti-aging actions, providing better dermatological health, and is used in creams for topical application. It also protects from the tanning effects of the sun.

  • Lowers Cholesterol Levels: Oral consumption of milk thistle aids in decreasing the blood cholesterol levels, imparts better heart health, and prevents stroke.

  • Supports Weight Loss: Milk thistle may also prove effective in reducing body weight when taken orally.

  • Decreases Insulin Resistance: Milk thistle has been claimed to reduce insulin resistance in type 2 diabetic patients and obese individuals. It may also make a permanent place for itself in diabetes management in the future.

  • Relieves Allergic Symptoms: Silymarin has an anti-inflammatory action which is particularly helpful in getting rid of asthma manifestations. It can also control the symptoms by regulating immune responses.

  • Limits Cancer Spread: The National Institutes of Health (NIH), U.S.A, has found that milk thistle intake can hamper the spread of cancerous cells and tumor growth and may even halt the disease in certain types. It also enhances the efficacy of chemotherapeutic drugs and may lower the adverse effects of cancer treatment. It is beneficial in the following types:

  • Prostate cancer.

  • Breast cancer.

  • Cervical cancer.

  • Leukemia.

  • Skin cancer.

  • Colorectal cancer.

However, milk thistle in cancer treatment has not been approved by the FDA yet.

  • Promote Bone Health: Milk thistle supports bone health by preventing bone loss, primarily caused due to deficiency of estrogen in women.

  • Enhances Cognitive Functions: Milk thistle may aid in preventing neurodegenerative conditions like Alzheimer's disease and improves cognitive functions by increasing resistance to oxidative stress.

  • Upgrades Immune Response: Due to the anti-inflammatory action of Silymarin, milk thistle improves the immune response of the body, and it also suppresses an overactive immune system in chronic inflammatory conditions.

How to Consume Milk Thistle?

Milk thistle is commonly marketed as supplements in the form of tablets, capsules, etc. However, there has been no recommended dosage set for its consumption in children and adults. So, it is advised to follow the manufacturer's instructions written on the package. It is also obtainable as tea, and its intake should be less than six cups a day.

What Are the Side Effects of Milk Thistle?

Although, milk thistle is safe for consumption. However, when taken in addition to other herbs, supplements, or medications, it may cause specific adverse effects, usually mild in intensity. They are listed as:

  • Stomach upset.

  • Diarrhea.

  • Nausea and vomiting.

  • Rash.

  • Heartburn.

Is Milk Thistle Safe for All?

Like all other herbs and supplements, milk thistle is not safe for everyone, and the following groups of people should avoid it:

  • Pregnant or lactating women.

  • People with a history of hormone-related cancers like breast and uterine cancer in females and prostate cancer in males.

  • Those allergic to ragweed, chrysanthemums, marigolds, chamomile, yarrow, or daisies.

Which Medications to Avoid With Milk Thistle?

The liver is the metabolism site for many of the routinely used drugs. Due to the effects of milk thistle on the liver, there are high chances of having drug reactions on consuming milk thistle. So, it is recommended to consult a doctor before starting the intake of milk thistle if another drug is being taken. However, the interactions with certain drugs are already known. Such medications are mentioned below:

  • Antipsychotics: Comprise butyrophenones (such as Haloperidol) and phenothiazines (like Chlorpromazine, Fluphenazine, and Promethazine).

  • Phenytoin (Dilantin): An anti-epileptic drug used to treat seizures.

  • Halothane: A drug used to induce or maintain general anesthesia.

  • Oral contraceptive pills or hormone replacement therapy.

The following drugs interact with milk thistle intake, as similar liver enzymes metabolize these medications and milk thistle.

  • Allergy drugs like Fexofenadine.

  • Drugs for treating high cholesterol levels: Involving statins, e.g., Lovastatin.

  • Anti-anxiety drugs: Including Alprazolam, Diazepam, and Lorazepam.

  • Antiplatelet and anticoagulant drugs (blood thinners): Comprising Clopidogrel and Warfarin.

  • Cancer-specific drugs like Raloxifene are used in breast cancer and osteoporosis.

  • Simeprevir: It is used in treating hepatitis C.

  • Sirolimus: It is an immunosuppressant.

  • Diabetes medications.


Milk thistle has important health benefits, especially for liver and gallbladder issues. However, very little evidence is available to prove its efficacy and safe use. It also interacts with several drugs causing severe complications. So, it should be taken only on recommendation by a doctor.


Last reviewed at:
02 Aug 2022  -  4 min read




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