How long should one wait before taking Valium if I already took 2 mg of Xanax. I know my dr told me not to take Xanax if I'll be taking the Valium but he didn't specify a time period to wait in between taking the Valium and Xanax. So, how many hours should I wait to take the Valium? I just took the Xanax an hour ago. Thanks in advance for any help!