Are there any contraindications or side effects from taking vitamin B12?

Cobalamin is a vitamin B complex vitamin that plays a key role in making the body function properly, both physically and mentally. Its deficiency is a disease that can become quite serious; therefore, there are many people who supplement themselves to ensure the necessary dose of the body. However, there is also concern about taking these supplements and the question of whether or not they are harmful to health and whether there are contraindications or side effects of taking vitamin B12. Let’s talk about it all below.

Why do we sometimes have to take B12 supplements?

All those people who eat food of animal origin consume B12 daily, because it is found in large quantities in these. However, there are certain population groups that need to take supplements so that their bodies do not suffer from a deficiency of this nutrient.

  • This is the case for people who follow a vegan or vegetarian diet. As we have pointed out, vitamin B12 is found in foods of animal origin, so it is necessary to cover this deficiency with supplements.
  • It is also the case that people over 50 years of age need an extra contribution, since their body stops absorbing this micronutrient in an appropriate manner as a result of age.
  • And, of course, there are people with some kind of disease in the digestive tract that does not allow them to absorb the vitamin they consume from food and, therefore, they have no other choice but to get it artificially.

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Well, in all these cases, supplementation becomes a necessity. Because this micronutrient has really important functions for our body, it is necessary to take it. In particular, cobalamin is responsible for the following functions:

  • Creating red blood cells: It is the most well-known function of this vitamin B12, which plays a leading role in the production of red blood cells, which transport oxygen to the cells through the blood.
  • Form DNA and RNA: It has a strong presence in the creation of DNA and RNA strands.
  • Improvement of the nervous system: It forms the sheath of the nerve fibers and helps the formation and regeneration of these.
  • Caring for the cardiovascular system: Vitamin B12 also takes care of homocysteine metabolism, thus protecting the cardiovascular system, largely avoiding certain diseases and pathologies associated with this amino acid.
  • Generate energy: Another of the most important functions is the transformation of fatty acids into energy.

Side effects from taking vitamin B12 supplements

Side effects from taking vitamin B12 supplements

Cobalamin, even taken in large doses, is not toxic, which is great news. However, it is true that some people have had side effects, although this is rare. In general, when supplements are taken in pill or pill form in cyanocobalamin form, the chances of side effects are virtually nil.

As explained in the previous point, there are people with some type of disease in their digestive tract who need to take vitamin B12 supplements. However, they cannot do it by mouth because their stomach would not absorb the pills either. They must be supplemented in such a way that the nutrient comes into direct contact with your bloodstream, which does not need to be absorbed by the body, such as B12 injections. Well, it is in this case that the side effects occur.

Some of the most common symptoms are:

  • Insomnia
  • Panic
  • Hives
  • Itching skin
  • Palpitations
  • Skin rash
  • Diarrhea
  • Anxiety
  • Breathing problems

However, in the vast majority of cases, people suffer these side effects from taking vitamin B12, not so much from cobalamin itself, but from the other preservatives present in the injection formula. Sometimes, even the contraindication is given by the format or presentation of the counter-indication. For example, hypersensitivity to punctures or in the mucous membranes when using nasal gels.

In certain cases, there are contraindications for people who may have allergies or sensitivity to cobalamin and cobalt. It is not advisable to take pure cobalamin supplements and it is only recommended to take them with foods rich in it.

Therefore, it is important to keep in mind that vitamin B12 has absolutely nothing wrong or contraindications, except for very specific cases, and must always be diagnosed by medical examination to rule out other types of allergies or intolerance. All those who follow a diet rich in animal and vegetable foods consume it daily and do not suffer from any symptoms due too much B12.

Side effects from not getting enough vitamin B12

The real problem comes when we don’t take enough cobalamine as we need, giving ourselves a lack of this micronutrient in the medium or long term. Vitamin B12 deficiency is a pathology with very negative consequences for health.

  • On the one hand, low cobalamin levels can cause cells to stop working. As we have pointed out, this nutrient plays a key role in the formation of red blood cells, which carry oxygen to the cells. If they don’t get enough, they don’t perform well, even to the point of not working.
  • Another of the most common consequences of having low levels of this vitamin is a nervous system failure, resulting in symptoms such as numbness and tingling of limbs.
  • The cardiovascular system can also suffer dire consequences; if homocysteine levels soar, certain diseases such as heart attacks or arrhythmias can appear.
  • Also, when we don’t have enough B12 we feel fatigue. We get tired earlier and it is also harder for us to do any physical activity.

As you can see, the health consequences of having low levels of vitamin B12 in your blood are disastrous. In addition, they are given not only for not consuming the vitamin but also for not taking a sufficient dose. Obviously, in this case the effects are much more subtle but they can get worse as we spend more B12 than we get.

Symptoms of vitamin b12 supplement poisoning


It is clear that taking vitamin B12 is essential for good health in the medium and long term. When consumed, either through food or supplements, it is stored in the liver, where it has a shelf life of two to three years. This is why it takes a long time for symptoms to appear, although the damage is taking place without us noticing it.

The likelihood of side effects from taking vitamin B12 as a supplement is minimal. These are most often given when people need to be treated with injections, prescribed by their doctor.

However, considering the health consequences of vitamin B12 deficiency, we strongly recommend taking this micronutrient supplement; the possible contraindications for taking it are minimal and much milder than the consequences of not having sufficient levels.

In addition, it is very important to lead a healthy and balanced lifestyle, with the consumption of food of both plant and animal origin, as well as the practice of exercise frequently. In this way, the organism works and functions better, both physically and psychically.

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Have you ever had any symptoms from taking B12 supplements? Comment it, I’m sure your experience will help more people!

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

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【Side Effects of VITAMIN B12】Symptoms & Treatment
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Comments 2

  1. Gali 14 November, 2017
    • Vitamina B12 14 November, 2017

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