why is my deltoid numb after b12 injection Tingling, numbness, or a “pins and needles” sensation in your hands or feet—especially if persistent—could be a sign of Vitamin deficiency. This vitamin vital for healthy nerve function, and when B12 Shots at Home: How,
Description
Annual blood tests at minimum are recommended to monitor the full nutritional profile, in line with BOMSS guidance

Open Biol (2019) 9(7):190109

B12 may be injected into a muscle or under the skin at 100 mcg daily for a week, every other day for another week, and then every three or four days for a month

prescription drugs by sales are largely expensive, specialized therapies (often biologics) for serious chronic illnesses (cancer, diabetes/obesity, autoimmune disease, etc.)
This helps doctors see if the treatment is working and if any changes are needed