Provided are methods of administering a vesicular monoamine transport 2 (VMAT2) inhibitor chosen from valbenazine and (+)-a-3-isobutyl-9,10-dimethoxy- 1,3,4,6,7,1 lb-hexahydro-2H-pyrido[2,l-a]isoquinolin-2-ol, or a pharmaceutically acceptable salt and/or isotopic variant thereof, to a patient in need thereof wherein the patient is also being administered a strong cytochrome P450 3A4 (CYP3A4) inhibitor.
