have been useing medtropin for the past 16 days , just put another order in with the deal they are doing . im useing 5 iu aday first day i took it i had pins and needle within 20-30 mins in my hands having very deep sleeps on it and waking up with numb hands in the mornings so its working for me but every one reacts differently as we all know . but thumbs up from me