How long does it take for doxpin(100mg) to get out of my system so that i can start taking amitriptyline (50mg) ?

Medications: The half life of doxepin is 15-25 hours. So after a day, th e blood level would drop 50%, after 2 days, to 25%, after 3 days, to 12.5, 4 days, 6.25% and 5 days, 3%. Asking the doctor who prescribed the amitriptyline to you would be useful, to be sure that s/he, and you, are crystal clear on what you are taking and to determine the best time to start medication.