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Vitamin B12 Supplement / Cyanide Antidote

Hydroxocobalamin (Vitamin B12)

Brand names: Cobalin-H (IM), Neo-Cytamen (IM), Cyanokit (IV — cyanide antidote)

Used in: Anaemia

Hydroxocobalamin is an injectable form of vitamin B12 used to treat B12 deficiency, including pernicious anaemia and deficiency from malabsorption or dietary causes.

Dosing — being independently re-sourced

ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.

Clinical monograph

How it works

It is converted to the active coenzymes methylcobalamin and adenosylcobalamin, which are required for DNA synthesis and red cell maturation and for normal neurological function.

Prescribing in practice

  • Establish the diagnosis before treating, as folic acid given alone in B12 deficiency can correct the anaemia while allowing irreversible neurological damage to progress.
  • It is given by intramuscular injection because oral absorption is unreliable in pernicious anaemia and other malabsorptive states.
  • Initiate replacement promptly where neurological involvement is present, with more frequent loading before maintenance.

Monitoring

Check a full blood count and reticulocyte response after starting, and monitor potassium during early treatment of severe megaloblastic anaemia.

Counselling the patient

  • Treatment for pernicious anaemia is usually lifelong and given as regular injections.
  • Report any new tingling, numbness or balance problems.
  • Attend for your scheduled maintenance injections to prevent relapse.

Evidence & guidelines

Hydroxocobalamin is recommended in NICE guidance on B12 deficiency as the standard parenteral replacement for pernicious anaemia and malabsorption.

Reference: BSH Guidelines on Cobalamin and Folate Deficiency 2014; NICE CG126; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

Pathways