What to do to relieve constipation caused from taking opiates?

ive been taking oxycodone due to a recent surgery i had a week ago. and i have become very constipated. i haven't made a bowel movement i a whole week when i use to go every 2 days. what should i do. should i just take a laxative. i cant stop taking the oxycodone because the pain some my surgery is too severe.