Actually medications will harm you more when you are fasting. If you must take medications because it is very necessary, stop fasting then take your meds.
Dr. Fuhrman says that he never allows his patients to Water Fast while on medications. He slowly helps them wean off of the meds and then makes them fast.
Understand one thing that all medications are designed with two goals, one, how to make a person feel better when they have illness, second, have small amount of substance that makes them addicted so that they can't quit easily. So medications don't help the cause of illness and do not make you feel better after some time, so the dosage has to be increased. All medications are harmful to your liver.