Injectable vitamin B12, benefits, risks and dosage

Cobalamin is one of the most important micronutrients for the body to perform many of its functions, which are also very important, such as the production of red blood cells, the generation and regeneration of DNA and RNA. In addition, B12 is indispensable in energy production. That is why it is so important to take supplements of this nutrient, in this case we will talk about the injections of vitamin B12, what are its indications, risks, side effects and for whom they are appropriate.

How does the body get vitamin B12? Absorption methods

The process of this micronurient is complex. Let’s take it one step at a time:

Synthesis and absorption

Our best selection

The first step, logically, to provide the body with the necessary vitamin is the absorption of it. Fatty acid plays a key role in releasing this from every food particle we consume. This is why some diseases related to the digestive system prevent its correct absorption, because they prevent the creation of this acid. Thus, peptidases from the stomach and small intestine release B12, which until then remains attached to proteins. Once released, it reattached to the R protein to prevent degradation by the acidic environment of the stomach. Finally, it binds to the protein synthesized by intrinsic factor. It is in the duodenum that the body finally absorbs the nutrient and is completely liberated.


Once absorbed by the body, it is transported to the liver, where it is stored for a period of two to three years. If a person has a certain hereditary defect related to the production of transcobalamines and/or their receptors, he or she is highly likely to suffer from deficiency. In order for this nutrient to be really useful for the body, it binds to a cell receptor; this is what is known as endocytosis. This is a process by which cells allow the introduction of other cells in order to form a gallbladder that is released and added to the fluid that remains inside the cells.

Storage and storage

Most of it is usually stored in the liver, but also in other organs such as the pancreas, kidneys, brain, and so on. However, it is important to remember that these warehouses have a shelf life of between 2 and 3 years. After that time, the vitamin disappears. That’s why it is so important to eat foods rich in this nutrient or supplements regularly. While it is true that storage is considerably more durable than other nutrients, it also has a limited time frame. Its deficiency is a serious disease that must be avoided at all costs. In addition, one of its major disadvantages is that it does not present symptoms until after 2 or 3 years; however, during this period of time it has caused functional damage to the body.


Excretion occurs when the organism has already stored the maximum B12 it needs. It is excreted through the bile. In case of an excess of cobalamin, it is excreted with urine without any kind of problem unless there is any pathology.

Do I really need vitamin B12 injectable?

Injectable vitamin B12, benefits, risks and dosage

There are two population groups at serious risk of B12 deficiency if they do not take supplements.

Vegan and vegetarian people

The explanation is very simple: cobalamin is mostly found in foods of animal origin, such as liver or salmon, to give a couple of examples. Although it is true that there are foods of plant origin such as tempeh or various marine algae that contain it, it is in very small quantities, insufficient to carry out their functions in our body. Therefore, their diet does not cover the amount the body needs.

People with malabsorption diseases

On the other hand, people who have some type of illness such as celiac disease or any other related to the digestive tract and which prevents them from absorbing or synthesizing B12 in a correct way.

Well, it is this second group that needs injectable vitamin B12 supplements because they come into direct contact with the bloodstream and are efficient in the absence of the body to absorb the nutrient.

Vegetarians and vegans, on the other hand, can cover their need for cobalamin with supplements in the form of pills, tablets, capsules or other forms of presentation. They are comfortable to take and do not require any follow-up or prescription as is the case with injections.

What are vitamin B12 injections for? Benefits

As we have pointed out, vitamin B12 injections are used in people with some kind of disease that prevent the correct absorption of the nutrient by the body. Its main benefit is that the nutrient comes into direct contact with the bloodstream after its application; therefore, it does not need absorption by the body, hence they are indicated for this type of patient.

For the rest of the population, however, other supplements such as B12 pills or sublingual supplements are much more convenient. They have the great advantage that they do not need to be prescribed by a doctor. There are also other types of supplements such as sprays or gels, which are very comfortable to apply and some of these are indicated for children.

Although people with cobalamin absorption problems and people following a diet without food of animal origin are those who must take mandatory vitamin supplements, although they are also highly recommended for the general population.

Are there any side effects from taking vitamin B12 injectable?

The main benefits of injectable ampoules of vitamin B12 are that they ensure proper absorption of this micronutrient, so that the body makes use of it and benefits from its properties completely. In addition, it provides immediate effects when applied by muscle.

For the side effects of vitamin B12 injectable supplements, if they are injected incorrectly, there may be pain, swelling, and even skin rashes. In addition, although they occur very rarely, adverse effects such as headaches, dizziness and vomiting can occur.

Cobalamin injection is always presented as a solution for intramuscular or subcutaneous injection. It is applied by nurses or qualified medical personnel for this task.

Is it possible to buy inexpensive vitamin B12 injections?

Vitamin B12 injections should be prescribed by a doctor. Therefore, it is essential to carry out an exhaustive study prior to the patient, which includes a blood test in order to determine the levels of cobalamin in the real body.

Once you have started treatment of injectable supplements, it is mandatory to keep a continuous eye on progress and this will always be continued under medical supervision so you will not find injectables available there and if you find them, they are illegal if sold without a prescription. In addition, they are not recommended at all because the origin and composition of these injectables is usually unknown, so the risks increase considerably.

Are there incompatibilities between B12 and some drugs?

Vitamin B12 Medications and Injections

It is very important to note that cobalamin is closely related to many medications. This is very important to know because there may be people who are taking a certain drug that is causing difficulties in absorbing this nutrient, and are not aware of it.

Medications that can interfere with injectable B12 are:

  • Chloramphenicol
  • Proton Pump Inhibitors
  • H2 histamine receptor antagonists
  • Metaformin

That’s just a few of the many drugs that can cause vitamin A deficiency in the medium to long term. For this reason, it is essential to consult with the medical staff before starting to apply injectables of cobalamin because many of these drugs interfere with the correct absorption of B12.

What are the appropriate doses of vitamin B12 injectable?

Depending on the case and the pathology suffered by each patient who has been prescribed this type of injections, the dose will be different. For people with neurological disorders and other nutritional deficiencies, a daily dose of 1-2 milligrams is usually recommended. There are different protocols of action and application of these injections, a typical protocol is to inject an ampoule of 1 mg per dose every 2 days, although as we have said this will depend on the individual situation of each patient and their vitamin B12 deficiency.

To continue with good blood levels of cobalamin, a maintenance dose of 1 mg per month is recommended. For children, this will vary depending on age, height and weight, so the most conscious thing is to consult the pediatrician to guide us in their supplementation intravenous B12. A standard of 0.4 to 1.8 mg doses is adopted.


In conclusion, cobalamin injectable ampoules are as safe and effective as any other supplement. Of course, they have their risks, but there is no need for any side effects if the injections are given correctly and at the right dose, and above all, they are first prescribed by the doctor.

In many cases, this type of supplement becomes indispensable as there are several diseases and pathologies that prevent the body from correctly absorbing and synthesizing B12. For this population group, injectable supplements are the best alternative to maintain adequate levels of this and, with it, have no health problems in the medium and long term.

Finally, we would like to stress how important it is to have adequate levels of vitamin B12 in the body. And, of course, whenever necessary, use supplements, whether injectable or otherwise.

Our best selection

Have you ever tried B12 injectable ampoules? If you have any questions, advice or experience to tell do not hesitate to do so in the comments.

If you found it helpful or have any questions, please comment and share, thank you! 😉

Fecha de revisión:
Artículo revisado:
[Total: 1 Media: 5]

Comment and Participate

   Acepto los términos de privacidad

  1. Responsable:
  2. Finalidad: Envío por email de noticias y novedades
  3. Legitimación: Tu consentimiento expreso
  4. Destinatario: Lista de suscriptores alojada en Wordpress
  5. Derechos: Acceso, rectificación, supresión, anonimato, portabilidad y olvido de sus datos