When to use milk thistle for hormones + when to think twice

milk thistle for hormones

With global sales expected to reach $120 million by 2024, milk thistle is having more than a moment. In fact, the plant has been used for more than 2,000 years for a variety of conditions. Thanks to a substance called silymarin found in its seeds, milk thistle is said to have lot of benefits for liver health, possible anti-cancer effects, hormone health, and beyond. Find out when you should consider milk thistle for hormones and who should say no to giving it go.

Milk thistle for liver & overall hormone health

Keeping your liver in good shape is essential to health and wellbeing. Many studies have found milk thistle has a liver-protective effect. It’s often used as a complementary therapy or alternative option for issues like alcohol-related liver disease, viral hepatitis C, and more.

But because it may improve some aspects of liver function, milk thistle supplements are being suggested for and embraced by an increasing number of people—even those without diagnosed liver issues.

The reason: the silymarin in milk thistle is an antioxidant. It improves the balance of free radicals and antioxidants in your body, which helps reduce oxidative stress. Oxidative stress is tied to inflammation and linked to a number of diseases, from cardiovascular conditions to Parkinson’s and beyond.

Another reason people take milk thistle is to improve hormone metabolization by the liver. It’s one of the liver’s jobs to process and eliminate excess sex hormones (estrogen, progesterone, and testosterone), hormones made by the adrenal glands, and thyroid hormones. If the liver isn’t working well enough to metabolize hormones, imbalances can occur.

When to consider milk thistle supplements

Along with supporting general liver health and hormone metabolism, milk thistle can help with:


breastfeeding mom

Problems with milk supply can happen for a number of reasons. (Definitely bring it up with your healthcare provider or a lactation consultant.) Though there isn’t too much scientific evidence reporting on milk thistle and breastfeeding, many women say the herb helps with increasing milk supply. Research from 2008 backs up those claims, noting women who took silymarin, a component of milk thistle, had a significant increase in lactation. This increase might be due to milk thistle helping with the hormone prolactin, which is responsible for milk production.


menopausal woman in park

Milk thistle is a phytoestrogen. When a woman’s estrogen levels are low (like during menopause and postmenopause), milk thistle may have a slight estrogenic effect. Some women find this helpful for symptoms like hot flashes and insomnia.

But along with reducing menopause symptoms, milk thistle is important because it improves bone health. It prevents bone loss and even affects bone growth, speeding up healing after a fracture. It also lowers cholesterol. LDL cholesterol and triglycerides naturally increase during this of life time and can increase risk for heart disease.

When you should think twice about milk thistle for hormones

Like all supplements, it’s important to check with your healthcare provider before taking milk thistle. Especially for those with certain conditions, milk thistle shouldn’t be taken at all or close monitoring may be needed.


woman with diabetes considering milk thistle

Milk thistle lowers blood sugar in some people. While this may be helpful for certain individuals, it’s possible for blood sugar to dip too low. Anyone with diabetes who is considering milk thistle should run it by a provider and weigh the pros and cons of taking it. Your blood sugar may need to be checked more often.


hypothyroidism and milk thistle

The thyroid gland produces hormones needed by every single cell. These hormones (T3 and T4) help regulate almost every process in the body. Metabolism, brain and bone health, muscle and nerve function, digestion, and more rely on thyroid hormones.

In order for thyroid hormones to do their job, they have to be able to get inside cells. Thyroid hormone transmembrane transporters help thyroid hormones cross cell membranes. But it’s possible milk thistle can hinder this process. A 2016 study reported milk thistle limits uptake of triiodothyronine (T3) by transmembrane transporters. As a result, cells may not get the amount of thyroid hormones that they need.

This can especially be an issue for anyone with hypothyroidism. Hypothyroidism means the body doesn’t produce enough or can’t use thyroid hormones effectively. Low thyroid levels slow body processes down. Because milk thistle affects how T3 gets transported to cells, it’s possible it could worsen hypothyroidism.

Milk thistle can interact with some medications

Milk thistle can interact with other medications and conditions. A few include:

  • Cholesterol-lowering medications
  • Allergy medications
  • Blood-thinning medications
  • Some forms of cancer treatment
  • Anti-anxiety medications

Milk thistle may also be a problem with hormonal birth control, hormone replacement therapy, seizure medications, and anesthesia. Be sure to check with a provider before taking a milk thistle supplement and bring up any questions, concerns, and share an accurate medical history.

Allergic reactions

Most people tolerate milk thistle well. But there are exceptions, and symptoms of an allergic reaction can take several days to get better.

Milk thistle belongs to the asteraceae plant family. (A few other plants in this family include ragweed, marigolds, and daisies.) Many providers may forget to ask, so know this: anyone with allergies to related plants may be more likely to also have a milkweed allergy. Share any known environmental allergies with your providerthey’re relevant!

Symptoms of an allergy to milk thistle vary:

  • Anaphylaxis (rare)
  • Stomach upset (bloating, pain, cramps, diarrhea, or loose stools)
  • Indigestion
  • Nausea
  • Itching skin
  • And more

How to take milk thistle

Most milk thistle capsules contain 70–80% silymarin. Doses up to 420 mg daily may be safe for most individuals, but your provider can help with a dose that’s right for you. Milk thistle is best taken about 30 minutes before a meal or snack.

It may be two to three weeks (or longer) before you notice whether or not milk thistle is having an effect. Along with talking with a professional about dose, continue to check in and carry on the conversation about how long you should take milk thistle for your hormones. Long-term use may not be recommended.