Many drugs can interfere with medications used during chemotherapy. They can do this in two ways:

• Reducing the effectiveness of chemotherapy medications. For example, vitamins A, E and C act as antioxidants and prevent the formation of ions that damage DNA. Normally, this is beneficial to patients. However, some chemotherapy medications produce these ions in an attempt to damage the DNA of cancer cells. Therefore, taking certain vitamins can prevent certain anti-cancer drugs from doing their job effectively.
  
  
• Worsening side effects associated with chemotherapy. For example, aspirin and related drugs can weaken blood platelets. In healthy people, this is not a major problem. However, anti-cancer drugs hamper bone marrow production of platelets, which are necessary for blood clotting. Therefore, aspirin may trigger bleeding problems in patients undergoing chemotherapy.

Physicians will want to know the following information about additional prescriptions, over-the-counter medications, nutritional supplements or herbal medications in a patient’s medication regimen:

• Name of drug
• Dosage level taken
• Reason drug is taken
• How often drug is taken

Physicians may suggest changes in their drug regime to reduce any likelihood of drug reactions in chemotherapy.