b12 injection benefits and side effects Vitamin Injections: What You Need To Know Vitamin B12 Shots Guide: Benefits

Some people report feeling more energized within a few days of their first shot

Percutaneous procedures such as radiofrequency rhizotomy, balloon compression, or glycerol rhizolysis may cause facial numbness, unpleasant tingling or dysesthesia, painful numbness known as anesthesia dolorosa, reduced corneal sensation, weakened blink reflex, masseter weakness, chewing difficulty, hematoma, vascular injury, cerebrospinal fluid leakage, infection, temporary cranial nerve dysfunction, incomplete pain relief, or recurrence

Int J Pharm Pharm Sci 3 Singh M, Chitranshi N, Singh AP et al (2012) An overview on fast disintegrating sublingual tablets

Usually, you get injections weekly at first