Milk Thistle
Milk thistle is a tall plant with large purple flowers that is native to Europe and was introduced into North America by early colonists. Milk Thistle is used for Historical and traditional use, Blood sugar control in type 2 diabetes and Liver diseases.
Also called: Silybon (India)
Pronunciation: pronunciation varies by local usage.
- Generic name
- milk thistle
- Drug class
- Herbal product marketed as a dietary supplement; main constituent of the extract is silymarin, a mixture of compounds
- Form
- Marketed as oral dietary supplement products; the supplied sources describe milk thistle extract and silymarin but do not specify a dosing form or dose.
- Route
- Oral
- Legal status
- Dietary supplement. Dietary supplements are not approved by the US FDA for safety or effectiveness before they are sold to the public.
Availability and supply rules vary by country
Trade names by country: India
Australia: · Full directory
What milk thistle is and how it works
Milk thistle is a tall plant with large purple flowers that is native to Europe and was introduced into North America by early colonists. It is also known as Mary thistle and holy thistle (Latin names: Silybum marianum, synonym Carduus marianus). The main constituent of milk thistle extract is silymarin, a mixture of compounds. Milk thistle is promoted as a dietary supplement for liver disorders, diabetes, and other conditions. (1) (2)
There is not enough high-quality evidence to allow definite conclusions to be reached about the effects of milk thistle on health conditions in people. Results for liver diseases have been conflicting or too limited to allow conclusions, and two NCCIH-funded studies (one on hepatitis C and one on non-alcoholic steatohepatitis) did not show benefits from silymarin supplementation. If you take any type of medicine, talk with your health care provider before using milk thistle or other herbal products, because some herbs and medicines interact in harmful ways.
Mechanism of action: how milk thistle works
Not established by the supplied sources. The sources describe milk thistle as a plant whose extract's main constituent is silymarin, a mixture of compounds, and note that interactions of silymarin with liver cells have been studied; they do not describe a mechanism of action for health effects. (1) (2)
What is Milk thistle used for?
Historical and traditional use
Historically, milk thistle was used for liver disorders and to increase breast milk production. It is currently promoted as a dietary supplement for liver disorders, diabetes, and other conditions. The supplied sources state that it is unclear whether milk thistle has an effect on breast milk production, and that it is not known whether milk thistle is helpful for other conditions. (1)
Blood sugar control in type 2 diabetes
Results from a small number of studies in people show that milk thistle extracts may help to control blood sugar in people with type 2 diabetes. Most of this research was done in Middle Eastern countries, and it is unclear whether the same results would be seen in other parts of the world. There is not enough high-quality evidence to allow definite conclusions to be reached about the effects of milk thistle on health conditions in people. (1)
Liver diseases
Results from clinical trials of milk thistle for liver diseases, such as alcohol-related liver disease, hepatitis B and C, non-alcoholic fatty liver disease, and liver problems caused by cancer chemotherapy, low oxygen levels, or toxins, have been conflicting or too limited to allow conclusions to be reached. Two NCCIH-funded studies, one on hepatitis C and one on non-alcoholic steatohepatitis (a progressive form of fatty liver disease), did not show benefits from supplementation with the milk thistle extract silymarin. (1)
Hepatitis C
Several studies of silymarin (milk thistle) dietary supplements in people with hepatitis C did not find beneficial effects. A 2014 evaluation of five studies of silymarin in people with hepatitis C, involving a total of 389 participants, did not show silymarin to be beneficial; the supplement did not improve liver function or decrease levels of the hepatitis C virus. One NCCIH- and NIDDK-cofunded study showed that higher-than-usual doses of silymarin, given for 24 weeks, were no better than placebo in improving a measure of liver function in people who had not responded to drug treatment for chronic hepatitis C; those receiving silymarin also showed no significant differences from placebo in hepatitis C virus levels or quality of life. (2)
Before taking milk thistle
Do not take / not appropriate for
- Do not assume that a product labeled "natural" is always safe. Many people believe that products labeled "natural" are always safe and good for them; this is not necessarily true. Herbal medicines do not have to go through the testing that drugs do, and some herbs can cause serious harm. (all products) (3)
- Do not use milk thistle without first discussing it with your health care provider if you take any type of medicine; some herbs and medicines interact in harmful ways. (all products) (1)
Tell your clinician about
- That you are taking or thinking about using milk thistle or another herbal medicine; make sure to tell your health care provider about any herbal medicines you are taking.
- Any allergy to related plants, for example ragweed, chrysanthemum, marigold, and daisy, because milk thistle may cause allergic reactions, particularly among people who are allergic to related plants.
- That you are pregnant or breastfeeding, or planning to be; little is known about whether it is safe to use milk thistle during pregnancy or while breastfeeding.
- All prescription and over-the-counter medicines you take, because some herbs can interact with prescription or over-the-counter medicines.
Milk thistle dosage and how to take it
- The supplied sources do not give a dose, dosing schedule, or dosing form for milk thistle; no dose is established by these sources.
- Milk thistle is promoted and sold as a dietary supplement; herbal medicines are sold as tablets, capsules, powders, teas, extracts, and fresh or dried plants.
- If you are thinking about using an herbal medicine, first get information on it from reliable sources.
- Talk with your health care providers about any complementary health approaches you use, so that together you can make shared, well-informed decisions.
- Do not use milk thistle in place of prescribed treatment for a liver condition, hepatitis C, diabetes, or any other condition; decisions about your treatment should be made with your health care provider.
Procedures and treatment changes
Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (1) (2) (3)
Missed dose
Not established by the supplied sources. The sources do not give a dosing schedule or dose for milk thistle, and no missed-dose guidance is provided. Discuss any questions about your supplement use with your health care provider.
Overdose
Not established by the supplied sources. These sources do not give an overdose amount or specific overdose guidance for milk thistle. If you are worried about a possible overdose or a reaction to a supplement, seek medical attention promptly and let the clinician you see assess the situation.
Milk thistle side effects
Milk thistle, when taken orally, appears to be well tolerated. In studies of silymarin in people with hepatitis C, side effects were uncommon and usually mild. Concerns have been raised about poor chemical and microbiological quality of milk thistle dietary supplements sold in the United States and other countries.
Digestive symptoms
What to notice: The most common side effects are digestive symptoms such as bloating, nausea, and gas. In hepatitis C studies, reported side effects were usually mild digestive problems, like bloating, indigestion, nausea, or diarrhea.
What to do: Discuss persistent or troublesome symptoms with your health care provider. (1) (2)
Allergic reaction
What to notice: Milk thistle may cause allergic reactions, particularly among people who are allergic to related plants (for example, ragweed, chrysanthemum, marigold, and daisy).
What to do: Seek medical attention promptly and let the clinician you see assess the reaction and advise on whether to continue or stop the product. (1)
Serious warnings
Supplement quality problems — serious
Symptoms: Not applicable. Concerns have been raised about poor chemical and microbiological quality of milk thistle dietary supplements sold in the United States and other countries. Some products have been found to contain amounts of silymarin substantially different from what is stated on the label or to be contaminated with pesticides, microorganisms, or mycotoxins (harmful substances produced by molds or other fungi).
Action: Be aware that contents may differ from the label and may be contaminated. Discuss the product with your health care provider or pharmacist; adverse effects or suspected contamination concerns should be assessed by a clinician. (1)
Interactions with medicines — serious
Symptoms: Not applicable. If you take any type of medicine, talk with your health care provider before using milk thistle or other herbal products; some herbs and medicines interact in harmful ways. Some herbs can interact with prescription or over-the-counter medicines.
Action: Talk with your health care provider or pharmacist before using milk thistle if you take any medicine, and give them a complete list of your medicines. (1) (3)
Use in pregnancy and breastfeeding — caution
Symptoms: Little is known about whether it is safe to use milk thistle during pregnancy or while breastfeeding.
Action: Discuss use during pregnancy or breastfeeding with your health care provider before using milk thistle. (1)
Interactions
| Medicine or test | Effect | Action |
|---|---|---|
| Prescription and over-the-counter medicines | Some herbs can interact with prescription or over-the-counter medicines, and some herbs and medicines interact in harmful ways. | Talk with your health care provider before using milk thistle or other herbal products if you take any type of medicine, and tell them about all medicines and herbal products you take. (1) (3) |
| Silymarin interactions with liver cells | The supplied sources note that interactions of silymarin with liver cells have been studied, but they do not describe specific interacting substances or clinical consequences. | Ask your health care provider or pharmacist to review possible interactions with your medicines and liver condition; the supplied sources do not provide a specific interaction list. (2) |
Pregnancy, breastfeeding, kidney/liver function, age
Pregnancy and breastfeeding
Little is known about whether it is safe to use milk thistle during pregnancy or while breastfeeding. Historically, milk thistle was used to increase breast milk production, but it is unclear whether milk thistle has an effect on breast milk production. Discuss use with your health care provider. (1)
People with allergies to related plants
Milk thistle may cause allergic reactions, particularly among people who are allergic to related plants (for example, ragweed, chrysanthemum, marigold, and daisy). Tell your health care provider about any such allergies. (1)
People with liver disease or hepatitis C
Clinical trials of milk thistle for liver diseases have been conflicting or too limited to allow conclusions to be reached, and several studies of silymarin supplements in people with hepatitis C did not find beneficial effects. Do not use milk thistle instead of treatment prescribed by your health care provider; discuss your liver condition and any supplements with your clinician. (1) (2)
Monitoring
Before starting
- Get information on the herbal medicine from reliable sources before using it.
- Tell your health care provider about any herbal medicines you are taking and about all prescription and over-the-counter medicines you use.
- Tell your health care provider about allergies to related plants (for example, ragweed, chrysanthemum, marigold, and daisy).
- Tell your health care provider if you are pregnant, planning a pregnancy, or breastfeeding.
During treatment
- Talk with your health care providers about any complementary health approaches you use, so that together you can make shared, well-informed decisions.
- Be aware that milk thistle dietary supplements have raised concerns about poor chemical and microbiological quality, including silymarin amounts substantially different from the label and contamination with pesticides, microorganisms, or mycotoxins.
- Report any side effects, such as digestive symptoms, or suspected allergic reactions to your health care provider.
Storage
Not established by the supplied sources. These sources do not provide storage instructions for milk thistle.
Professional information
Clinician-facing context only. Use the current local regulatory status and product information. Dietary supplements are not approved by the US FDA for safety or effectiveness before sale; manufacturers and distributors of supplements are responsible for evaluating the safety and labeling of their products before marketing to ensure that they meet all regulatory requirements.
All regions
Indication: Any milk thistle use
Dose summary: No dose is displayed. The supplied sources do not give a dose, dosing schedule, or dosing form for milk thistle.
Renal context: Not established by the supplied sources. (1)
Hepatic guidance
The supplied sources state that results from clinical trials of milk thistle for liver diseases have been conflicting or too limited to allow conclusions to be reached, and that several studies of silymarin in people with hepatitis C did not find beneficial effects. No hepatic dosing or monitoring guidance is provided.
Overdose note
Not established by the supplied sources. No overdose amount or specific overdose management guidance is provided. (1) (2)
Frequently asked questions
Does milk thistle help liver disease or hepatitis C?
Results from clinical trials of milk thistle for liver diseases, such as alcohol-related liver disease, hepatitis B and C, non-alcoholic fatty liver disease, and liver problems caused by cancer chemotherapy, low oxygen levels, or toxins, have been conflicting or too limited to allow conclusions to be reached. Two NCCIH-funded studies, one on hepatitis C and one on non-alcoholic steatohepatitis, did not show benefits from supplementation with the milk thistle extract silymarin. A 2014 evaluation of five studies in people with hepatitis C, involving 389 participants, did not show silymarin to be beneficial. (1) (2)
Does milk thistle help control blood sugar in type 2 diabetes?
Results from a small number of studies in people show that milk thistle extracts may help to control blood sugar in people with type 2 diabetes. Most of this research was done in Middle Eastern countries, and it is unclear whether the same results would be seen in other parts of the world. There is not enough high-quality evidence to allow definite conclusions to be reached about the effects of milk thistle on health conditions in people. (1)
Is milk thistle safe?
Milk thistle, when taken orally, appears to be well tolerated. The most common side effects are digestive symptoms such as bloating, nausea, and gas. Milk thistle may cause allergic reactions, particularly among people who are allergic to related plants (for example, ragweed, chrysanthemum, marigold, and daisy). Little is known about whether it is safe to use milk thistle during pregnancy or while breastfeeding. If you take any type of medicine, talk with your health care provider before using milk thistle or other herbal products. (1)
Can I trust that a milk thistle supplement contains what the label says?
Concerns have been raised about poor chemical and microbiological quality of milk thistle dietary supplements sold in the United States and other countries. Some products have been found to contain amounts of silymarin substantially different from what is stated on the label or to be contaminated with pesticides, microorganisms, or mycotoxins (harmful substances produced by molds or other fungi). (1)
Is milk thistle regulated like a medicine in the United States?
Many herbal products intended for oral use are marketed as dietary supplements. The rules for making and distributing dietary supplements are less strict than those for drugs, and unlike drugs, dietary supplements are not approved by the US FDA before they are sold to the public. When public health concerns arise about the safety of a dietary supplement or an ingredient including an herb, the FDA can take action to protect the public. Manufacturers and distributors of supplements are responsible for evaluating the safety and labeling of their products before marketing. (1)
Does milk thistle increase breast milk production?
Historically, milk thistle was used to increase breast milk production. The supplied sources state that it is unclear whether milk thistle has an effect on breast milk production, and that little is known about whether it is safe to use milk thistle while breastfeeding. Discuss use with your health care provider. (1)
What is the mechanism of action of milk thistle?
Not established by the supplied sources. The sources describe milk thistle as a plant whose extract's main constituent is silymarin, a mixture of compounds, and note that interactions of silymarin with liver cells have been studied; they do not describe a mechanism of action for health effects. (1) (2)
What is the generic name of Milk Thistle?
The generic name is milk thistle. (1)
What class of drug is milk thistle?
Milk Thistle is classed as: Herbal product marketed as a dietary supplement; main constituent of the extract is silymarin, a mixture of compounds. (1)
References
- Milk Thistle: Usefulness and SafetyNIH National Center for Complementary and Integrative Health · United States · dated February 2025 · accessed 2026-10-13 · source 1
- Hepatitis C and Dietary SupplementsNIH National Center for Complementary and Integrative Health · United States · dated May 2018 · accessed 2026-10-13 · source 2
- Herbal MedicineMedlinePlus, US National Library of Medicine · United States · accessed 2026-10-13 · source 3
Brand names by country
Single-ingredient milk thistle names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.
Priority countries
India
- Silybontablet · 70 mg, 140 mg · Micro Labspharmacy source recorded
- Inlife Milk Thistle Extract (80% Silymarin)veg capsule · 600 mg, 800 mg · Inlifepharmacy source recorded
- HK Vitals Milk Thistle Extractcapsule · 600 mg · HK Vitals (HealthKart)pharmacy source recorded
- Myfitfuel Milk Thistle Extract (80% Silymarin)capsule · 600 mg · Myfitfuelpharmacy source recorded
- GNC Herbal Plus Milk Thistlecapsule · 250 mg · GNCpharmacy source recorded
- Dr. Morepen Milk Thistle+capsule · 60-capsule pack, strength not stated on listing · Dr. Morepen (Morepen Laboratories)pharmacy source recorded
- Pure Nutrition Milk Thistle Liver Detoxtablet · 60-tablet pack, strength not stated on listing · Pure Nutritionpharmacy source recorded