I guess it depends on the size of the person being injected and how much fat there is to go through to get into the muscle. These injections are in the muscle not subcutaneous. My daughter is four and weighs 37 pounds. We use a 25G 5/8 needle. We’ve had longer ones but they were harder to use because we were supposed to stop short of the end of the needle and it was scarier than knowing that all of it is supposed to go in. These work fine to suck up the meds and deliver.
We ask our endo for them as they require another RX which I find ridiculous. I can fill the solucortef but am not allowed, on the same RX, to get the means to deliver it by! Crazy silly world. Good luck, Julia