Drug Interaction Report

Interferon beta-1a may cause liver problems, and using it with other medications that can also affect the liver such as entrectinib may increase that risk. You should avoid or limit the use of alcohol while being treated with these medications. Call your doctor immediately if you have fever, chills, joint pain or swelling, unusual bleeding or bruising, skin rash, itching, loss of appetite, fatigue, nausea, vomiting, abdominal pain, dark urine, pale stools, and/or yellowing of the skin or eyes, as these may be signs and symptoms of liver damage. Talk to your doctor or pharmacist if you have any questions or concerns. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

Do not consume grapefruit, grapefruit juice, or Seville oranges during treatment with entrectinib. Doing so can significantly increase the blood levels of entrectinib and increase the risk and/or severity of side effects such as dizziness; confusion; hallucinations; problems with concentration, attention, thinking, and memory; mood changes; insomnia; drowsiness; liver problems; increased uric acid levels in the blood (hyperuricemia); congestive heart failure; fluid retention and swelling; changes in electrical activity of the heart (a condition known as QT prolongation, which may lead to irregular heart rhythm that can be life-threatening); vision problems; and low red or white blood cell counts. Talk to your doctor if you have any questions or concerns. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.