According to the prescribing information for cyanocobalamin injection, the product is a sterile solution of cyanocobalamin for intramuscular or subcutaneous injection. The same label states that it is indicated for vitamin B12 deficiencies due to malabsorption that may be associated with a list of named conditions. This guide reports those label statements and what the label says about oral supplementation.
What cyanocobalamin injection is
The label cited here is one repackager's label of an approved cyanocobalamin injection product. It describes Cyanocobalamin Injection, USP as a sterile solution of cyanocobalamin for intramuscular or subcutaneous injection.
The clinical pharmacology section states that vitamin B12 is essential to growth, cell reproduction, hematopoiesis, and nucleoprotein and myelin synthesis. It also states that cyanocobalamin is quantitatively and rapidly absorbed from intramuscular and subcutaneous sites of injection, and that the plasma level of the compound reaches its peak within 1 hour after intramuscular injection. That sentence concerns the level of the compound in plasma. It gives the time to the peak only. It says nothing about how long a level lasts, and it does not measure any symptom.
MedlinePlus, a patient information page from the National Library of Medicine, states that your body cannot make vitamin B12 on its own, so you have to get it from the foods you eat.
What the label lists as indications
The indications section is built around deficiency caused by malabsorption. These entries are statements about people with a vitamin B12 deficiency, not about people without one. The lead-in says the deficiencies "may be associated with" the listed conditions. That wording links the deficiencies to the conditions. It does not say that everyone with one of the conditions has a deficiency.
| Label entry | What the source says |
|---|---|
| Lead-in wording | Cyanocobalamin is indicated for vitamin B12 deficiencies due to malabsorption which may be associated with the following conditions. |
| Addisonian (pernicious) anemia | Listed in the indications section. |
| Gastrointestinal pathology, dysfunction, or surgery | Listed in the indications section, including gluten enteropathy or sprue, small bowel bacteria overgrowth, total or partial gastrectomy. |
| Fish tapeworm infestation | Also listed in the indications section. |
| Malignancy of pancreas or bowel | Also listed in the indications section. |
| Folic acid deficiency | Also listed in the indications section. |
| Vitamin B12 absorption test (Schilling test) | The label states the product is also suitable for this test. |
What the label says about oral vitamin B12
The label makes two statements about the oral route, and they concern different groups.
First, it states that requirements of vitamin B12 in excess of normal (due to pregnancy, thyrotoxicosis, hemolytic anemia, hemorrhage, malignancy, hepatic and renal disease) can usually be met with oral supplementation. That statement is about requirements above normal, not about a diagnosed deficiency.
Second, the clinical pharmacology section states that oral absorption is considered too undependable to rely on in patients with pernicious anemia or other conditions resulting in malabsorption of vitamin B12. That statement is about people with malabsorption.
Which groups the label statements concern
Three groups appear in the label text quoted above. The indications concern people with a vitamin B12 deficiency due to malabsorption. The oral supplementation statement concerns people whose requirements are in excess of normal. The statement on oral absorption concerns patients with pernicious anemia or other conditions resulting in malabsorption.
None of the quoted statements is about people who fit none of these three groups. This guide therefore does not carry the label's wording over to them. The label gives no dose or schedule in the wording quoted here, and this guide does not supply one.
What this does not tell you
These are label statements, not trial results. The label statements quoted here do not report how any group of people felt or functioned, so this guide makes no claim that an injection changes energy, mood, memory or weight. This guide also reproduces only the sections quoted above, not the whole label, and the label cited is a repackager's copy of an approved product's label.
None of the statements quoted here is a trial comparing oral vitamin B12 with injection. No source used in this guide describes a compounded vial. Whether any product fits a person is a decision for a licensed provider.