b12 injections absorb into plastic Cobalex® 2000 Injection 500mL B12 Injections - Maryland Plastic
Description
Vitamin B12 injections may be administered in the arm or other regions with excess subcutaneous fatty tissues like the buttocks, thigh, or abdomen

Dec 2019;119(12):2053-2063

Others prefer oral products because they do not involve needles

Since the vitamin bypasses the digestive system, you benefit from maximum absorption and effectiveness
