does a b12 injection make you tired Why do I feel worse after injection: causes explained b12 injections how often should
Description
The injection is administered quickly, and any discomfort usually subsides within minutes
Regulatory documentation

HFD high-fat diet mice in the vehicle cohort received three subcutaneous (SC) saline (1 ml/kg) injections/day ( 0930, 1330, 1730 h) and mice in the treatment cohort received three SC injections of the NNMT inhibitor 5-amino-1MQ at a dose of 20 mg/kg/injection for a total dose of 34 mg/kg/day of the parent compound (calculated according to free weight) for 11 days
But if you get them from a trusted source (more on that below), it couldnt be safer or easier