Which one are you taking and how long have you taken it? The pharmacist said 4-6 weeks but my doctor said six months. I am taking mine five days then if needed sooner to contact the pharmacist. The pharmacist said it needed to be taken every two days every month. The pharmacist said we will have to work with it to see how well it works. We are doing panzyga for CIDP and mmn- mulifocal motor neuropathy.