Patients should consult their physician before taking any other medication (either prescription or over-the-counter) or nutritional supplements. Most medications should be taken at least one hour before or four to six hours after the resin. Bile acid resins may prevent other medications from working properly. Of particular concern to patients taking bile acid resins are:

• Anticoagulants. Medications that inhibit blood clot formation. Because certain bile acid resins (cholestyramine, colestipol) interfere with the effectiveness of some anticoagulants, physicians will often order routine blood tests to closely monitor coagulation.
  
  
• Inotropes. Medications that strengthen the heart’s contractions so that it can circulate more blood with fewer heartbeats.
  
  
• Diuretics. Medications that cause the kidneys to flush water and other substances (e.g., sodium) from the body through urine. 
  
  
• Certain antibiotics (e.g., penicillin G, tetracycline and the oral antibiotic vancomycin). Medications that kill or slow the growth of harmful microorganisms, such as bacteria (they have no effect on viruses). They are used to treat some infections and are given before medical/dental procedures to prevent infections in some patients. 
  
  
• Certain NSAIDs (nonsteroidal anti-inflammatory drugs. NSAIDs (e.g., phenylbutazone) are medications that are commonly used to reduce pain and inflammation. 
  
  
• Certain beta blockers (e.g., propranolol). Medications that reduce the workload of the heart and lower blood pressure. They are commonly used to treat high blood pressure, angina (a certain type of chest pain, pressure or discomfort associated with coronary artery disease) or heart failure. 
  
  
• Certain thyroid hormones. Thyroid hormones are substances important to the development or function of virtually all tissues and organs. People with low levels of thyroid hormones in their blood often take synthetic thyroid hormones to meet their body’s needs. 
  
  
• Grapefruit juice. Grapefruit juice interferes with the liver’s ability to break down (metabolize) some medications. This, in turn, can cause a toxic build-up of the medication in the blood. While the buildup is less likely if the juice is ingested four or more hours prior to the medicine, patients taking medications are advised to refrain from taking them with grapefruit juice. Patients may also be instructed to avoid eating grapefruit.