Are itchy scalp and excessive shedding after using Propecia a bad sign?

You may be experiencing an allergic reaction. I suggest a consultation with a cosmetic dermatologist with experience in hair restoration and maintenance. Some great options for hair restoration and maintenance are prp injections which can stimulate hair growth. Hope this helps.

You may be allergic. I suggest seeing a hair loss expert now to evaluate and go over your condition and provide you information about your best treatment options. There are great non-invasive options like prp/progesterone and/or hair transplantation. 
See an expert. Best, Dr. Emer

Thank you for your question! This is likely how your body is reacting to the treatment. It is neither good nor bad. I would speak to your provider who can look at your scalp to make sure this is not a problem. Best of luck!