Treatment for diagnosed B12 deficiency

The B12 Institute specialists work according to the ‘Guidelines for the diagnosis and treatment of Cobalamin and Folate disorders’ by the British Committee for Standards in Haematology’. Look for more information here: 

We also adhere to the procedures set up by the NHG and the Medical Specialists Federation. If neccesary an underpinned decision is made to deviate from those procedures.

Standard treatment

The main treatment consists of i.m. injections, according to the Farmacotherapeutisch Kompas (Pharmatherpeutic Compass) and its information leaflet.


Open this link to find information on the dosage:


Profylaxis and vitamin B12 deficiency treatment: starting dose: intramuscular or deep subcutaneous: 10 injections Hydroxocobalamin of 1000 mcg with an interval of at least three days; maintenance dose of 1000 mcg once every two months or 300 mcg once a month. Supplementation: lifelong, if the underlying cause has not been solved or removed.

Treatment when there is a clear pattern of neurological symptoms.

In case of clear neurological deviations we provide Hydroxocobalamin: 10 injections of 1000 mcg once or twice a week, over two years, e.g.

In our practice and based on numerous signals by patient associations, we have noticed  that standard maintenance dosage often is insufficient. This has also been described in specialist literature. Very often complaints return some time after they disappeared. Moreover, maintenance dosage is sometimes prescribed when symptoms are still present. In view of the seriousness of this disease this is not a suitable option. Overdosage is impossible: the Gezondheidsraad (Dutch Health Council) has not issued an upper limit. Too much hydroxocobalamin will be cleared renally; also, in cases of very serious (neuro-) psychiatric diseases the neccesity of deviating from the standard is always proficienty discussed.

We focus on patient-oriented treatment.

Possible side effects 

  • headache (often: 1 to 10%)
  • acne, acneiform dermatitis
  • allergic skin reactions, such as eczema and exanthem, caused by cobalt
  • allergic reactions, such as itching, urticaria (sometimes)
  • anafylactic shock (very seldom: < 0,01%)

 Early treatment decline

Both practical experience and literature on the subject show that sometimes symptoms and complaints get worse after starting the suppletion intake (cf the side effects described above), disappearing after a few days or weeks. This phenomenon cannot be explained entirely from a chemical perspective, but we should certainly refrain from concluding that  in these cases B12 deficiency was an incorrect diagnosis. Therefore this phenomenon should not lead to stop treatment after having been diagnosed with symptomatic B12 deficiency. Consulting the treating physician is necessary.

Attention 1

We sometimes see people becoming impatient because of the slow recuperation process, which is perfectly understandable, but we advise strongly against the use of methylcobalamin or adenosylcobalamin / methylfolate (orally or by means of injections) without prescription, because there is a chance of moderate or serious side effects. B12 deficiency, especially with complaints that began long before treatment started, is a serious illness, with a slow recovery process.

Attention 2

B12 deficiency treatment leads to the production of new erytrocytes. In case of anemia and/or decreased erytrocytes, this may cause an increased intracellular use of potassium, possibly resulting in serious potassium deficiency (hypokalemia).  This usually takes place at the start of the injection treatment. Adequate treatment and monitoring are necessary.

Using hydroxocobalamin cannot lead to intoxication

All scientists in this specialist field of study agree that neither hydroxocobalamin i.m / i.v. nor Cobalamin can be overdosed. This has also been underpinned by the Dutch Health Council, which has indicated no upper intake limits for these substances (2003) and by the Dutch Tuchtraad ( Disciplinary Board) in 2011, when a GP was sued for having prescribed B12 injections (once a month)  for a diagnosed B12 deficiency after gastric bypass surgery. During the treatment the patient experienced prickling, but it was not made clear whether this was the result of early treatment decline or undertreatment. Since then it has become known that for some patients, especially those with decreased IP because of gastric bypass surgery,  one injection a month is insufficient.

It is, however, possible that patients show (pseudo-) allergic to injections. Here, too, the same rule is applied: we offer patient-oriented, customised treatment. 

Can potassium levels be increased by hydroxocobalamin injections? One of our patients, who also visited another hospital, showed an increase of potassium values after being examined  by doctors there. They concluded that the increase was caused by the B12 injections; they found that the patient had possibly been overdosed because of the injections. However, a potassium atom cannot be released into the body by the hydroxycobalamin molecule. The laboratory nor the hospital realised that the potassium measurements also measured the potassium chemically linked with the hydroxo molecule.

Free potassium measurements have so far not taken place in the Netherlandsm yet. Therefore there will always be increased results, appearing to be the rsult of intoxication.

Attention 3: Oral suppletion

We prefer the use of injections for treatment of diagnosed symptomatic B12 deficiency, in particular if that goes along with neurological disorders. Hydroxocobalamin is the only approved medication for this disease, included in basic health insurance by provided by the Dutch Zorg Instituut Nederland (National Health Care Institute Netherlands). However, over the years more and more publications have appeared apparently proving that injections might be replaced by oral suppletion, because ‘they may be equally effective’.

Sometimes we are asked for scientific literature proving that injections are more effective than oral suppletion. That should be the other way round, of course: injections are the Gold standard in treating symptomatic B12 deficiency, oral medication is not.

That injections are the Gold standard stands to reason, since they avoid the entire absorption problem: the path through the body meat,  fish, butter, cheese and eggs take Patients show a B12 level of more than 1475 pmo/L within a minute after being injected.

In view of the progressive nature and seriousness of the disease, and the irreversibility of some of the clinical symptoms, we are convinced that in case of doubt treatment should be by injections. ‘Wait and see’ is not a proven option. Whenever there are clear neurological symptoms, the choice of adequate treatment should be the most effective one, particularly when other diseases have been ruled out.


Treatment of neurological or serious B12 related symptoms by injections is also a good and efficient option for children. Many publications show that people are deeply concerned about the effects of B12 deficiency for children in the long term. Therefore we should choose the most effective option.

If a child reacts negatively to an injection, the medication can be adjusted or oral suppletion can be given.

The same rule applies here: patient-oriented treatment. All patients are different, and they all receive customised treatment. 

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