There is no known pharmacological interaction from same-day administration
Product quality, sterility, and appropriate patient selection matter
Nope, go to the gym or get liposuction
But, and this is a big but, you should always talk to a healthcare professional before starting any new supplement
Intrinsic factor, Medline Plus, Vitamin B12, Fact Sheet for Consumers, National Institutes of Health, Office of Dietary Supplements, Vitamin B12, Fact Sheet for Health Professionals, National Institutes of Health, Office of Dietary Supplements Pawlak R
These animal findings may help explain split timing in informal protocols, but they cannot set a safe dosing frequency or predict subcutaneous timing in people