Drug Interaction Report

Neratinib may significantly increase the blood levels of relugolix. This may increase the risk and/or severity of side effects such as hot flushes; weight gain; decreased sex drive; erectile function difficulties; muscle and joint pain; constipation; diarrhea; increases in glucose, triglyceride (fat), and liver enzyme levels; and decreased hemoglobin levels. It may also increase the risk of an irregular heart rhythm that may be serious and potentially life-threatening, although it is a relatively rare side effect. Talk to your doctor if you have any questions or concerns. Your doctor may be able to prescribe alternatives that do not interact, or you may need a dose adjustment or more frequent monitoring to safely use both medications. If you do have to take both medications, you should take relugolix first, then take neratinib after at least 6 hours to minimize the effects of the interaction. 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 can increase the blood levels of neratinib. This may increase the risk and/or severity of side effects such as diarrhea, nausea, vomiting, abdominal pain, mouth sores, loss of appetite, and liver problems. You should avoid the consumption of grapefruit and grapefruit juice during treatment with neratinib. Be sure to take the medication with food at the same time everyday to maintain consistent blood levels and effects. Talk to your doctor or pharmacist if you have questions on how to take this or other medications you are prescribed. 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.