clearblue fertility monitor+letrozole

Hey friends, I'm thinking of buying clearblue fertility monitor but I'm also on letrozole. Do you think I still get the results while take fertility meds? I'd tried to search if that is ok as I'm getting it today-my 2nd day period. Tomorrow I will start taking my letrozole. The monitor is pretty expensive so just curious I can use it while on letrozole. Pls help! Thanks