0.2 mg/day grows 82% as much hair as 1mg, which grows 83% as much hair as 5mg. twice a week is good enough. side effects come from reduced serum dht levels, which return to normal in about a week. only the dht produced in your hair follicles for your hair follicles matters. dht from the blood is responsible for maybe 5% of the lost hair. finasteride stops dht production inside the cells, where 5ar2 is. the reaction does not take place outside the cells. blood dht gets there when a little dht leaks out of cells. from there it is metabolised by the liver even faster than excess finasteride.