Drug Interaction Report

Peginterferon beta-1a may cause liver problems, and using it with other medications that can also affect the liver such as cobimetinib 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.

Grapefruit juice may increase the blood levels and effects of certain medications such as cobimetinib. You may want to limit your consumption of grapefruit and grapefruit juice during treatment with cobimetinib. However, if you have been regularly consuming grapefruit or grapefruit juice with cobimetinib, do not alter the amounts of these products in your diet without first talking to your doctor or other healthcare professional. Contact your doctor if your condition changes or you experience increased side effects. Orange juice is not expected to interact.