Dear Dr. Rassman:
I have some questions regarding the possible side effects of taking propecia, and I am wondering if you can help to answer them?

1. After a patient starts his medication on propecia, how long will it take for the possible side effects, such as gynocomastia to occur?
2. If gynocomastia does occur, would it be completely reversible after the patience stop using propecia?
3. If a patient stopped using propecia, will the severity of hair loss process accelerate? Or would the patient simply lose the hair gained from using propecia? If that assumption is valid, would a patience who stopped taking propecia only 1 or 2 weeks into the medication also experience acceleration of hair loss?

Thank you so much for you patience and time.

1. Breast enlargement or nodules is a rare side effect of Propecia (I suspect one in 500 people might see it at the 1mg dose) and it will usually occur in the first month.
2. If breast problems do occur, they will disappear within a month or so upon stopping the medication.
3. Stopping Propecia for 1-2 weeks probably will produce some withdrawal hair loss, but I suspect it will be hard to see and relatively small. The longer you stop the medication, the worse the withdrawal loss will be and the more irreversible it will become.