Is it possible that finasteride 1mg worsen hair loss after 4yrs of regular use?

Hair loss: While anything is possible, Finasteride doesn't typically cause hair loss despite regular use. It stops the conversion of Testosterone into Dihydrotestosterone which is poisonous to hair follicles. Perhaps your T is higher such that your DHT is higher. Non-genetic hair loss can also be due to stress (both emotional & physical). infection, thyroid disease & malnutrition. Consider topical Minoxidil.

No Hair Scare Here: It decreases the amount of hair loss based on a hormonal adjustment but generally won't grow back that which has been lost(some exceptions).Also, whatever factors that may contribute to hair loss persist(stress, nutrition, hair care,generic etc) and in individual cases there might need to be a dose adjustment. Some hair may shed due soley to finasteride at the beginning of treatment but not later