My daughter has type 1 diabetes. She used to use emla to change her sight. She is on an insulin pump and the sight is the tubing where the insulin goes in under the skin, kind of like an IV. She needs to change her sight every 3 days which means she needs to insert the thin tubing with a needle and then remove the needle and leave the tubing under the skin. Anyway it really did help with the pain but she had to apply the emla for an hour before the procedure and keep the area covered with saran wrap and tape so it would absorb into the skin. She was at band camp a few years ago and it was too late to apply the emla so she just did it without and has never used the emla since. Her doctor, kind of, discouraged using it but I felt like whatever eased her pain since she had to deal with so much of it was her decision. It did seem to cause some minor irritation but she was using it every 3 days. My opinion is that if it is a painful procedure and your child is extremely sensative, use it. If it just for routine shots, I would just try a divertisment for the 2 seconds. My 3 kids never use it for their regular shots. My diabetic daughter also has blood drawn every 3 months and does not use it for that. One important thing is to make sure the alcohol dries before injection so it doesn't sting. One more thing, my neice who is a red head and grown now but her mother used to use emla before shots. Red heads are proven to feel more pain and actually need more anethstesia. Good luck, shots are never fun.
