Oral vitamin B12 – what are the prescribing considerations and what formulations are available?

This Medicines Q&A outlines what oral vitamin B12 (cyanocobalamin) preparations are available and associated prescribing considerations.

  • Hydroxocobalamin 1mg administered intramuscularly (IM) is the preferred method of treatment for non-diet-related vitamin B12 deficiency (e.g. pernicious anaemia) as it is retained in the body longer than cyanocobalamin.
  • Oral cyanocobalamin 50-150micrograms daily is used to treat diet-related vitamin B12 deficiency.
  • Where administration of IM hydroxocobalamin is not possible (e.g. during a pandemic) or not tolerated, oral cyanocobalamin may be considered as an alternative, provided sufficient doses are taken (at least 1mg for non-diet-related deficiency) and there is good compliance with treatment.
  • Cyanocobalamin 1mg tablets are available as a food supplement (immediate-release, modified-release or sublingual tablets) or as a prescription-only medicine that is unlicensed in the UK but can be imported; they can be obtained through community pharmacies (some stock is classified as a wholesaler ‘special’).
  • A licensed cyanocobalamin 1mg tablet (Orobalin) is due to be launched in the UK in July 2020.
  • Cyanocobalamin 50microgram tablets are available as Pharmacy only medicines or as food supplements.
  • Cyanocobalamin tablets must be prescribed as “cyanocobalamin tablets” and should not be written as “vitamin B12 tablets”.
  • In Wales, cyanocobalamin tablets can be prescribed for patients who are vegan or with a proven diet-related vitamin B12 deficiency only for the purpose of treating or preventing vitamin B12 deficiency, and the prescription must be endorsed ‘SLS’; this does not apply in England, Northern Ireland or Scotland, or when prescribing for patients with non-diet-related vitamin B12 deficiency in any of the countries.