Vitamin B12, or cobalamin, is absorbed from food in the stomach with the help of a protein known as intrinsic factor, according to the University of Maryland Medical Center, or UMMC. Patients who lack intrinsic factor cannot absorb vitamin B12 and require injections of the water-soluble vitamin to prevent a deficiency. It is administered as an intramuscular injection.
Deltoid
Vitamin B12 is injected in the deltoid muscle, which is a muscle in the upper arm, according to Drugs.com. The injection is made deep into this muscle at an angle of 90 degrees. The syringe should be pulled back slightly once the vitamin is injected to check for blood. Blood in the syringe is a sign that a vessel has been hit. If blood is present, the vitamin should not be administered and a different injection site should be used. Vitamin B12 injections should not be done continuously on the deltoid to prevent scar formation, which can interfere with its absorption.
Ventrogluteal
The ventroglutueal, or hip muscle, is a good spot for injecting vitamin B12 because there is little danger of hitting blood vessels and nerves, according to Drugs.com. Injections at the hip muscle are only suitable for adults and children over 7 months. Infants do not have well-developed ventrolgluteal muscles for injections at this site.
Vastus Lateralis
The vastus lateralis, or thigh muscle, is another injection site option, according to Drugs.com. The vastus lateralis is mainly used in children under 3 years old because there is little danger of hitting blood vessels and nerves, and the muscles are well developed.
