What happens if you go on and off propecia over time?

Propecia works by lowering DHT (dihydrotestosterone) levels. This hormone is the culprit that in thinning and eventual hair loss seen in male pattern baldness.  Since hair cycles between a rest and active phase, Propecia will effect cycling time.  When hair is in the rest phase, telogen, hair is asleep and not growing.  I have seen patients cause a longer than usual sleep phase which results in shedding.  Patients need to make a commitment when starting Propecia to stay on it unless side effects ensue.  You could be less responsive to Propecia than before or the thinning you are experiencing could be secondary to increased shedding.  It would be a good idea for you to follow up with your physician.

Studies of what happens when people go on and off have never been done. However, it's clear in my mind that men who cycle on and off tend to respond poorly over time. If started a constant dose is advised. Please see your hair loss physician to review dosing and frequency.

Genetic loss can get to the point where it is not reversible. Finasteride, if used, must be consistent. When you goi off of if, then you may lose hair permanently