I started using it on my daughter Carmen when she was 11/2 years old and she is 3 now. Before that she used to cry and struggle when they draw the blood and sinced using it she has been fine and told me that 'its not so painful anymore', so I guess that it works! It usually take about 1 hour to take effect, so what we do is to get the cream from the doctor and apply it at home before going to the hospital. For my daughter, because she has faint veins, we usually apply it on several locations, i.e., both wrists and both feet, so that the doctor has more options and that we got all the likely locations covered. Good luck! Sue.