Milk thistle is an herbal supplement that’s been around for thousands of years. It’s usually taken for liver disease, but it may also help control diabetes.

Although milk thistle is a popular supplement, it’s not right for everyone. For example, if you’re allergic to ragweed, there’s a chance you’ll have a bad reaction to milk thistle. Allergies to other plants, including chrysanthemums, daisies, and marigolds, can also mean you’re allergic to milk thistle. If you want to try milk thistle for insulin control with diabetes but are concerned about a ragweed allergy, here’s what you should know.

What Is Milk Thistle?

Milk thistle is a fast-growing plant. It has large leaves with white veins running through them that release milky white sap when crushed. Supplement manufacturers turn milk thistle seeds into pills, powders, and liquids to help with various health problems.

Traditionally, milk thistle has been used for liver and gallbladder disease. Milk thistle has anti-inflammatory and antioxidant properties that are thought to help protect liver cells against conditions like cirrhosis (liver scarring) and hepatitis (a viral infection). Emergency rooms use milk thistle to counteract the toxic effects of poisonous mushrooms that damage the liver.

Some people have become interested in milk thistle for high blood sugar and high cholesterol. However, the evidence on milk thistle for these conditions is mixed. It’s not recommended as a replacement for proven medical treatments.

Milk Thistle and Diabetes

Silymarin is one of the main active compounds in milk thistle. Some studies have suggested that silymarin could potentially help type 2 diabetes and some of its complications.

For example, a systematic review published in Obesity Medicine in 2021 found that silymarin had positive effects on fasting blood sugar and hemoglobin A1c (HbA1c) — both measures of blood sugar important to people with type 2 diabetes. However, the scientists state that more research needs to be done before they can draw any solid conclusions about the benefits of milk thistle for type 2 diabetes.

Another systematic review published in 2024 looked at the effects of silibinin (the main compound in silymarin) on type 2 diabetes and its complications. The authors state that silibinin may help control diabetes in several ways, including decreasing insulin resistance. The review found antidiabetic effects of silibinin, like reduced blood glucose levels. It also stated that silibinin may help diabetes complications like neuropathy (nerve damage) and osteoporosis (bone weakening).

Researchers say that more work is needed to understand how milk thistle and its active compounds may affect type 2 diabetes. It can be hard to predict how milk thistle will affect someone with diabetes, especially if they already take medication with similar effects. It’s possible that milk thistle will lower blood sugar too much and cause other issues.

Although milk thistle is generally considered safe, some people have side effects like:

• Bloating
• Constipation
• Diarrhea
• Headache
• Itching
• Nausea
• Vomiting

Milk thistle can also affect levels of the hormone estrogen, which can promote some types of cancer, like ovarian cancer and uterine cancer. In addition, a handful of medications interact with milk thistle, such as warfarin (a blood thinner) and raloxifene (for osteoporosis), to name a few. Ask a pharmacist if you’re unsure about mixing supplements with your prescriptions.

If your doctor feels it’s safe for you to try milk thistle with diabetes, keep a close eye on your blood sugar levels. Monitoring your blood sugar more often can help you see how milk thistle affects your body. It’ll also give you a better chance of catching dangerously low blood sugar levels that need immediate attention.

Milk Thistle and Ragweed Allergies

If someone says they’re allergic to pollen, they usually mean ragweed pollen. Ragweed is a common plant that grows across the U.S. When levels are high, ragweed causes some level of allergic reaction in about 20 percent of people.

An allergic reaction to ragweed can feel like a cold and include symptoms such as:

• Coughing
• Itchy eyes
• Skin rash
• Sore throat
• Stuffy nose
• Trouble breathing (if you have asthma)

Some people with ragweed allergies also get allergy symptoms when eating certain foods. These foods have a protein that’s similar to ragweed and can trigger a reaction:

• Artichokes
• Bananas
• Cantaloupe
• Chamomile
• Sunflower seeds
• Watermelon
• White potatoes
• Zucchini

Allergies to milk thistle and ragweed can go hand-in-hand. The allergic reaction may be mild or severe and life-threatening. An allergist can run tests to help determine if you’re allergic to milk thistle, ragweed, or other related allergens.

Members of DiabetesTeam have talked about their experience with ragweed allergies. “I cannot eat anything in the melon group. I have tried a few times in the past when I did not know about the link,” shared one member.

“When I try to eat watermelon or cantaloupe, as soon as it hits my tongue, I get an aversion to it and my tongue gets a prickly feeling, kind of like a numbness. It is hard to explain, but it actually tastes so awful to me. A doctor told me about the link between certain foods and ragweed. But I am able to eat cucumbers, bananas, tomatoes, and many other foods,” they explained.

You can learn a lot by paying attention to how your body reacts to different foods and things in your environment, like pollen. Bringing your suspicions to your healthcare provider can help confirm whether you have an allergy or not.

Should You Take Milk Thistle?

You shouldn’t take milk thistle if you’re allergic to ragweed. Ragweed allergies are relatively common. You may not know you’re allergic to ragweed unless you get tested. Generally, people who have eczema (a skin condition), asthma, or a family history of allergies are more likely to develop other allergies. If that’s you, be extra careful before starting an herbal supplement like milk thistle. Or, get tested for allergies first.

Unlike prescription medications, dietary supplements aren’t tightly regulated. As a result, the label doesn’t always accurately reflect what’s inside the package. Supplements can contain ingredients that aren’t listed on the label. Supplements may also have higher or lower doses of the herb that’s being advertised. These issues make supplements risky, especially when you have a health condition, like diabetes.

You shouldn’t take milk thistle or any other dietary supplements without the medical advice of your healthcare provider. Supplements can have serious side effects, including allergic reactions, and can’t replace diabetes treatment. Instead, healthy lifestyle changes, like a nutritious diet, stress management, and regular exercise, are better ways to supplement your diabetes care.

Talk With Others Who Understand

DiabetesTeam is the social network for people with diabetes mellitus and their loved ones. On DiabetesTeam, members come together to ask questions, give advice, and share their stories with others who understand life with diabetes.

Are you allergic to ragweed? What are your thoughts on natural medicines like milk thistle extract? Share your comments below, or start a conversation by posting on your Activities page.