What is injectable B-12?

Cyanocobalamin, also known as vitamin B-12, is a substance the human body requires in very low doses that it normally acquires through food. Some patients may require additional vitamin B-12 for a variety of reasons and obtain it through injection, as described by MedlinePlus.

Vitamin B-12 is used by the human body to derive energy from fat and carbohydrates during protein synthesis, reports WebMD. While everyone needs B-12 for proper health, most people do not require supplementation of B-12 and get all they need from their diet. Some individuals do not, however, including patients suffering from pernicious anemia, who lack a natural substance needed to absorb vitamin B-12 from the intestine; patients taking medications that interfere with the body's absorption of B-12; and patients suffering from some diseases and infections, explains MedlinePlus. Because B-12 is principally obtained through animal products and is not present in fruits, grains and vegetables, strict vegans who consume exclusively nonanimal-derived products may be vitamin B-12 deficient.

Injectable B-12 is available only through prescription, and is injected either subcutaneously beneath the skin or into muscle tissue, WebMD notes. Numerous potential side effects of injectable B-12 include diarrhea, muscle cramps, headaches and dizziness, reports MedlinePlus. Patients should report any symptoms that develop after beginning a course of injectable B-12 therapy to the prescribing physician.