• Milk thistle is believed to aid in healthy liver function.thistle image by Paul Knott from Fotolia.com
  
  Milk thistle (Silybum marianum) is a common alternative medicine for patients who have liver or digestive complaints. Although generally considered safe, it does have some contraindications. A contraindication is a circumstance in which taking a medication may cause harm. This circumstance may be an existing health condition that makes the use of milk thistle hazardous, or a drug or supplement that interacts negatively with milk thistle.
  
  

Drug Interactions

• Milk thistle may interfere with certain types of prescription medication.drugs image by alimat from Fotolia.com
  
  According to the University of Maryland Medical Center, milk thistle can interfere with medications that are broken down by the same liver enzyme, which include common drugs for allergies, anxiety, cancer, and high cholesterol, as well as certain blood thinners.
  
  Milk thistle may also interfere with certain antipsychotic and anti-seizure medications.
  
  Always consult your medical professional before taking milk thistle or other supplements.
  
  

Preexisting Conditions

• People who are allergic to artichokes may be sensitive to milk thistle.Artischocke image by Andrea Leitold from Fotolia.com
  
  People who are pregnant, lactating or suffering from severe liver disease should not begin a regimen of milk thistle. Patients with existing gastrointestinal maladies---including nausea, diarrhea, bloating, abdominal pain, and gas---should not use milk thistle unless advised by a physician.
  
  Individuals who are allergic to ragweed, artichokes, kiwi, the aster family, or common thistle should avoid the use of milk thistle.
  
  The use of milk thistle is contraindicated for people who have been diagnosed with uterine fibroids, endometriosis, or uterine, breast or ovarian cancer.
  
  

Adverse Effects

• Milk thistle use may cause headaches.upset girl image by Vasiliy Koval from Fotolia.com
  
  One of the major components of milk thistle is silymarin, which is known to increase bile secretions by stimulating the liver and gall bladder. This increase in bile may have a mild laxative effect for two or three days. Other possible side effects of milk thistle include headache and rash.
  
  Taking too much milk thistle may cause changes to the female user's menstrual cycle.
  
  Milk thistle may decrease blood glucose levels in diabetics, which may interfere with preexisting therapy for hypoglycemia or hyperglycemia. In these instances, caregivers should carefully monitor the patient's blood glucose levels.
  
  A small number of milk thistle users have reported symptoms like loss of appetite, gas, heartburn, joint pain and impotence. Although milk thistle may not have caused these symptoms, you should always report any unusual symptoms to your doctor while taking milk thistle or other supplements.