Milk Thistle Allergy: Symptoms and Treatment

Updated September 28, 2022
Field of milk thistle

Even though a milk thistle allergy is rare, it can occur. The best way to prevent this allergic reaction is to understand where milk thistle comes from so you can avoid contact. It is also helpful to understand the potential side effects of a thistle rash so you can identify it if it happens to you or a loved one. Armed with this knowledge, you should be able to determine whether using milk thistle is right for you.

What Is Milk Thistle?

Milk thistle (Silybum marianum) is a member of the Asteraceae family and is native to Europe. The plant gets its name because its leaves have white spots resembling drops of milk and also because the leaves contain a substance with a milky sap texture and appearance.

Brown seeds of a milk thistle plant in late autumn

The leaves contain several points and are thorny, while the stem is thick and smooth. The plant blooms in late spring or early summer and sports a large pinkish-purple flower. The seeds from the flower head are harvested to make milk thistle products.

What Is Milk Thistle Used For?

Milk thistle contains an ingredient called silymarin that is used as an anti-inflammatory and antioxidant, according to the National Cancer Institute (NIH). Common purported uses include treatment for liver disease, poisoning, and disease prevention although not all of these benefits are supported by strong scientific evidence.

Liver Disease

There may be a few ways that milk thistle benefits the liver according to the NIH.

  • People with liver disease may be prescribed milk thistle because the chemicals in the extract, which are called flavonolignans, help stimulate the liver into growing new cells.
  • For people with liver cancer that are taking chemotherapy treatments, milk thistle may help protect against damage to the good cells within the liver.
  • Milk thistle also helps remove toxins from the liver through protein synthesis and is used to treat various liver ailments such as hepatitis, cirrhosis, and fatty liver disease.

Mushroom Poisoning

Amanita mushroom poisoning, though rare, is often deadly. If milk thistle is given within 48 hours of ingestion, the survival rate increases dramatically.


Though research is still pending, there are several clinical trials looking at milk thistle as a complementary treatment for cancer, says Cancer Research UK.


Though additional research is pending, initial studies indicate the ingredients in milk thistle may also help lower cholesterol levels of the "bad" LDL type and increase levels of the "good" HDL cholesterol. This effect has been shown in rats, according to the Journal of Clinical & Diagnostic Research.

Milk Thistle Allergy Symptoms

Milk thistle can cause an allergic reaction in some individuals. It typically features the same allergic reactions found when in contact with other members of the Asteraceae family, such as ragweed, daisy, marigolds, and chrysanthemums, according to the National Center for Complementary and Integrative Medicine.

The symptoms of this allergic reaction can vary. However, a few notable reactions included in a Allergy, Asthma, and Clinical Immunology case report include:

  • Burning of the mouth
  • Congestion
  • Coughing
  • Difficulty swallowing
  • Hives or rash
  • Itching
  • Sneezing
  • Swollen tongue
  • Trouble breathing

Milk Thistle Allergy Treatment

If you suspect you have had an allergic reaction to milk thistle, it is imperative you seek medical attention immediately and to immediately stop taking all milk thistle products. However, specific symptoms also have specific treatments.

  • Your healthcare provider may suggest that hives be treated with an over-the-counter medication such as Benadryl.
  • For rashes your provider may suggest that you apply calamine lotion or corticosteroid creams to relieve the itching.
  • For severe reactions, your healthcare provider may require you to carry an epinephrine pen which will allow you to inject yourself in the event you have significant trouble breathing. The epinephrine pen contains adrenaline to reduce your body's response to the allergen found in milk thistle.

Remember to communicate with your healthcare provider before using milk thistle for any benefits. Together, you and your physician can determine if this plant can be beneficial. If you notice signs of a milk thistle allergy, stay in contact with your provider to determine the best treatment.

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Milk Thistle Allergy: Symptoms and Treatment