i hit myself in the upper outer glute and have had no problems...maybe a little sore the next day..nuttin out of the ordinary... a friend of mine is hitting in the same spot and told me he was in so much pain last nite he couldnt even sleep? said he even felt lightheaded this morning? we are both using the same product..just different bottles of course....is he hitting a vein? nerve? he said this has been happening his last 3 injections...and its just getting worse..he hits his upper right ass once a week