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B12 Treatment



  • Hydroxocobalamin injections are used to treat B12 deficiency by the NHS in the UK. It is a very stable form of B12 and is converted to methylcobalamin and adenosylcobalamin in the body.

    In the UK injectable B12 is only available on prescription. You CANNOT overdose! It is used in huge quantities as a treatment for cyanide poisoning. It is also used in the treatment of Leber's optic atrophy.

    If B12 deficiency is due to malabsorption, injections will be required for life. Once diagnosed, correct treatment is a loading dose; intramuscular B12 injections of hydroxocobalamin every other day for two weeks. This frequency should continue for patients with neurological involvement, until all symptoms stop improving, followed by lifelong maintenance doses of hydroxocobalamin at two-monthly intervals.

    This is stated in NICE and BNF Guidelines but is unfortunately very often ignored and many patients are restricted to a maintenance regime of 3 monthly injections. This is not nearly enough for many patients and is not based on clinical evidence but came about as a result of cost saving exercises! For help with tackling this please read more here.

  • Oral cyanocobalamin is suitable only for the small number of people with proven dietary deficiency of vitamin B12. See this BMJ article. 

  • Injectable cyanocobalamin is commonly used in the US and Canada and some European countries. This form converts to hydroxocobalamin and then to methylcobalamin and adenosylcobalamin in the body. It is a very stable form but is considered inferior to hydroxocobalamin and it can worsen Leber's optic atrophy. It is also advised that smokers do not use cyanocobalamin.
    Please note: American patients may be able to access hydroxocobalamin via prescription from both CVS and Walgreens pharmacies.

  • Methylcobalamin (active B12) - It is available in injection form in the UK from private doctors or available over the counter in the form of; sublingual lozenges, capsules, sublingual sprays, nasal sprays and patches. It's important to note that these supplements do not help everyone.

  • Adenosylcobalamin - another form of active B12 this can also be used in injection form but more commonly as a sublingual lozenges, liquid drops or powder.

  • Please note: we are all different and we may respond differently to the individual forms of B12. Some patients require a combination of forms.

Click here for NICE Guidelines on treatment of B12 deficiency.


It is wise to take a good vitamin B complex in addition to your B12 injection as all B vitamins need each other to work properly, supplementing one in isolation will cause an imbalance in others.

  • If you are B12 deficient it is essential to have your folate (vitamin B9) and ferritin levels (iron storage) monitored in order to make sure you optimise your healing. Your doctor may not be aware of this!

  • During early intensive B12 treatment potassium levels may fall, causing hypokalemia, so please increase your intake of potassium rich foods.

  • It is advisable to obtain copies of all your blood test results and to learn how to read them.

  • Many with this condition are both folate and iron deficient and if you feel no improvement with B12 treatment alone please investigate further.

  • Your MCV level (mean corpuscular volume) which is tested as part of full blood count will also be key in determining macrocytosis - (large red blood cells). Please note macrocytosis may not be present in B12 deficiency.

  • Please click here to read the in depth key information on results, written and compiled by Pat Kornic.

    You can view a 90 minute broadcast on B12 deficiency with me, from the Academy of Physical Medicine here. There is a small charge. See a small clip here

    If you have a smart phone you may be interested in the apps we have developed, our monitor app will help to chart your journey on treatment and keep vital information in one place. We have also developed an app to help determine your risk of B12 deficiency.
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