What happens if you take milk thistle every day?

October 7, 2025 •

4 min read

According to extensive review, milk thistle is generally considered well-tolerated with few side effects when taken daily for extended periods, but the scientific evidence for many of its health claims is still under debate. This article explores what happens if you take milk thistle every day, examining its potential benefits, risks, and crucial considerations for long-term use.

Quick Summary

Daily milk thistle use is generally safe for most but can cause mild digestive issues or allergic reactions. While it may offer antioxidant benefits and support liver health, its efficacy for treating chronic conditions remains inconclusive. Potential interactions with medications and contraindications for specific health conditions are important to consider before use.

Key Points

Generally Safe: Oral milk thistle is typically well-tolerated, even with long-term daily use within recommended doses, according to multiple studies.
Potential Liver Support: Due to its antioxidant and anti-inflammatory properties, daily intake may support liver health and function, though evidence for treating severe liver diseases is mixed.
Considerable Drug Interactions: Milk thistle can interact with many medications, particularly those metabolized by the liver, including some for cholesterol, diabetes, and hepatitis C.
Possible Mild Side Effects: Users may experience mild gastrointestinal issues such as gas, bloating, or diarrhea, and in rare cases, allergic reactions.
High-Risk Groups Exist: Those who are pregnant, breastfeeding, have hormone-sensitive conditions, or certain allergies should avoid daily milk thistle unless advised by a doctor.
Consult a Professional: Due to varying quality and potential interactions with medications, it is vital to consult a healthcare provider before starting daily milk thistle supplementation.

An Overview of Milk Thistle and Silymarin

Milk thistle, or Silybum marianum, is a flowering herb related to the daisy and ragweed family, historically used to address liver and gallbladder problems. The key active ingredient is a flavonoid complex called silymarin, which is primarily found in the seeds of the plant. Silymarin is believed to provide the main therapeutic benefits due to its antioxidant, anti-inflammatory, and potential antiviral properties. While many manufacturers tout milk thistle's benefits, it is important to remember that herbal supplements are not regulated by the FDA in the same way as drugs, and the body of scientific research is still evolving.

Potential Benefits of Daily Milk Thistle Intake

Daily supplementation with milk thistle is most commonly associated with supporting liver health, though its effects are not limited to this organ. The potential benefits are often linked to the antioxidant and anti-inflammatory properties of silymarin.

Liver Protection and Support: Silymarin is believed to protect liver cells from toxins by reducing free radicals produced as the liver metabolizes toxins. Some studies suggest it might support liver cell regeneration. Research on severe conditions like cirrhosis and chronic hepatitis C has yielded mixed or inconclusive results, but some studies show promise in treating nonalcoholic fatty liver disease (NAFLD).
Blood Sugar Management: Some research indicates that milk thistle may help lower blood sugar levels and improve insulin resistance in people with type 2 diabetes. This effect warrants caution and close monitoring for those on diabetes medication, as it could lead to hypoglycemia.
Potential Neurological Benefits: Due to its antioxidant and anti-inflammatory effects, milk thistle may offer neuroprotective benefits, potentially helping to prevent age-related decline in brain function. Animal studies suggest it could help protect against conditions like Alzheimer's and Parkinson's disease. However, more research is needed to determine if this effect is stronger than that of a diet rich in other antioxidants.
Skin Health: The antioxidant and anti-inflammatory properties of silymarin have shown promise in reducing acne lesions in small studies. Other research suggests it may protect skin against the harmful effects of sun exposure.
Bone Health: Some animal studies have indicated that milk thistle may help protect against bone loss and stimulate mineralization in bones, which could be relevant for osteoporosis prevention. Human studies are needed to confirm these findings.

Potential Risks and Side Effects of Daily Milk Thistle

While generally well-tolerated, taking milk thistle every day is not without potential risks and side effects. Most adverse effects are mild and can be managed by adjusting the dosage or discontinuing use.

Mild Gastrointestinal Issues: The most common side effects reported include digestive symptoms such as nausea, bloating, gas, diarrhea, or changes in bowel habits.
Allergic Reactions: People with allergies to plants in the Asteraceae family (like ragweed, daisies, marigolds, or chrysanthemums) are at a higher risk of experiencing an allergic reaction to milk thistle, which can range from a rash or itching to a severe anaphylactic reaction.
Hormone-Sensitive Conditions: The active compounds in milk thistle might affect estrogen levels. Therefore, individuals with hormone-sensitive conditions such as breast, uterine, or ovarian cancer, endometriosis, or uterine fibroids should consult a doctor before starting a daily regimen.
Drug Interactions: Milk thistle can interact with many medications, particularly those processed by the liver's cytochrome P450 enzyme system. It can affect the levels of certain drugs, including:
- Diabetes medications, potentially causing blood sugar levels to drop too low.
- Some cholesterol-lowering statins.
- Specific hepatitis C medications like simeprevir.
- Immunosuppressants such as sirolimus.
- The osteoporosis medication raloxifene.

Comparing Benefits and Risks of Daily Milk Thistle Use


Feature	Benefits	Risks
Efficacy	Potential antioxidant, anti-inflammatory, and liver-protective effects.	Efficacy for many severe conditions is unproven or based on conflicting evidence.
Side Effects	Most people tolerate daily use with few, if any, side effects, even for several years.	Mild and temporary digestive upset, such as gas, bloating, or diarrhea.
Safety	Considered generally safe for most healthy adults within recommended doses for several months.	Risk of allergic reactions for individuals sensitive to the daisy family.
Interactions	Appears to have no significant drug interactions in some studies, but mixed data exists.	Can interact with medications metabolized by the CYP450 enzyme, as well as diabetes drugs and others.
Contraindications	No contraindications for most healthy individuals.	Should be avoided by those with hormone-sensitive conditions or certain allergies.

Who Should Avoid Daily Milk Thistle?

While many people can take milk thistle daily without issue, several groups should exercise caution or avoid it entirely. Always consult a healthcare provider before beginning any new supplement, especially if you fall into one of the following categories:

Pregnant or Breastfeeding Individuals: The safety of milk thistle during pregnancy and breastfeeding is not fully established.
Individuals with Allergies: Anyone allergic to plants in the Asteraceae family should avoid milk thistle due to the risk of allergic reactions.
Those with Hormone-Sensitive Cancers: Individuals with breast, uterine, or ovarian cancer should seek medical advice due to potential estrogenic effects.
Diabetics: People with diabetes must use caution and closely monitor their blood sugar, as milk thistle may lower blood glucose levels.
Individuals on Specific Medications: Anyone taking drugs that interact with the CYP2C9 enzyme, such as warfarin, or other specific medications like simeprevir or sirolimus should discuss it with a healthcare professional.

Conclusion: Is Daily Milk Thistle Right for You?

Daily milk thistle use is widely regarded as safe for the general population within typical dosages and may offer antioxidant and liver-protective benefits. However, the efficacy of milk thistle for treating many chronic diseases remains either unproven or inconclusive, and it is not a substitute for conventional medical treatment. The potential for mild side effects, allergic reactions, and significant drug interactions means that consulting a healthcare provider before starting daily use is crucial. For those with underlying health conditions or on regular medication, medical guidance is non-negotiable to ensure safety and avoid potential harm. For a deeper scientific perspective on silymarin, consider exploring resources from the National Institutes of Health (NIH).

Frequently Asked Questions

Yes, oral milk thistle appears to be generally safe and well-tolerated for daily use over several months or even years in most people. However, safety is not universal, and it is essential to discuss long-term use with a healthcare provider.

The most common side effects are mild gastrointestinal disturbances, including bloating, gas, nausea, and diarrhea. These are usually brief and may diminish with continued use or a dosage adjustment.

Milk thistle contains silymarin, which acts as an antioxidant and anti-inflammatory agent, and may support liver cell regeneration. While it shows promise for conditions like nonalcoholic fatty liver disease (NAFLD), its effectiveness for severe conditions like hepatitis C or cirrhosis has been inconclusive in some studies.

If you have diabetes, you should use milk thistle with caution and under medical supervision. Some studies indicate that it can lower blood sugar levels, which could interact with your diabetes medication and potentially cause hypoglycemia.

Yes, milk thistle can interact with several medications, including some processed by the liver's CYP2C9 enzyme, certain diabetes drugs, specific hepatitis C medications like simeprevir, and immunosuppressants. You should always inform your doctor about any supplements you are taking.

Individuals who are pregnant, breastfeeding, have allergies to plants in the daisy family, or have hormone-sensitive conditions (like some types of cancer) should avoid or consult a doctor before using milk thistle.

There is no standard timeline for experiencing benefits, and results can vary depending on the individual and health condition. Some studies on conditions like NAFLD have lasted several weeks or months. It is best to follow medical guidance and monitor your body's response.