Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.

Other medications can affect the removal of tucatinib from your body, which may affect how tucatinib works. Examples include rifamycins (such as rifabutin, rifampin), St. John's wort, drugs used to treat seizures (such as carbamazepine, phenytoin), among others.

This medication can slow down the removal of other medications from your body, which may affect how they work. Examples of affected drugs include avanafil, some benzodiazepines (such as midazolam, triazolam), daridorexant, ergot drugs (such as ergotamine, dihydroergotamine), finerenone, mavacamten, pacritinib, some "statin" drugs (such as lovastatin, simvastatin), ubrogepant, among others.