Hydroxocobalamin at a glance
Medicine class
Vitamin B12 replacement; Cyanokit is also a cyanide antidote.
How it is given
Vitamin B12 products are injected into a muscle. Cyanokit is given by intravenous infusion in an emergency.
Food and drink
Food does not affect hydroxocobalamin injections.
What is Hydroxocobalamin used for?
Selected UK products are licensed for:
Pernicious anaemia and other macrocytic anaemias caused by vitamin B12 deficiency.
Prevention of vitamin B12-deficiency macrocytic anaemia following gastrointestinal surgery or with malabsorption or a restrictive diet.
Tobacco amblyopia and Leber’s optic atrophy.
Cyanokit: emergency treatment of known or suspected cyanide poisoning in any age group, alongside decontamination and supportive care.
How does Hydroxocobalamin work?
For deficiency, hydroxocobalamin replaces vitamin B12 needed for DNA synthesis, normal red-cell formation and neurological function. In cyanide poisoning, it binds cyanide to form cyanocobalamin, which can be eliminated in urine.
Hydroxocobalamin preparations and strengths
Solution for infusion
Route: Intravenous
Strengths: 5 g
Injection
Route: Parenteral
Strengths: 1000 micrograms/mL
How to take Hydroxocobalamin
A healthcare professional administers hydroxocobalamin. Cobalin-H and Neo-Cytamen are injected into a muscle; Cyanokit is prepared and infused intravenously in an emergency.
Attend arranged injection and monitoring appointments.
Tell the clinician about previous reactions to hydroxocobalamin, vitamin B12 or cobalt.
After Cyanokit, tell healthcare staff and laboratories that it was given because its deep-red colour can affect some test results.
Hydroxocobalamin side effects
Common or expected effects
- Pain, swelling or itching at the injection site
- Nausea or vomiting
- Diarrhoea
- Headache or dizziness
- Hot flushes
- With Cyanokit, temporary red discolouration of skin, mucous membranes or urine
Get urgent medical advice
- Anaphylaxis or another severe hypersensitivity reaction
- Palpitations or an abnormal heart rhythm, including arrhythmia associated with low potassium during initial deficiency correction
- Severe or blistering skin reaction
- After Cyanokit, acute kidney injury or marked blood-pressure changes
Hydroxocobalamin in pregnancy
Hydroxocobalamin may be used for confirmed vitamin B12 deficiency during pregnancy. Specialist input is appropriate for vitamin B12-deficiency anaemia. Cyanokit may be used for suspected cyanide poisoning when the emergency benefit outweighs uncertain fetal risk.
Hydroxocobalamin while breastfeeding
Hydroxocobalamin used for vitamin B12 replacement passes into breast milk in small amounts and can generally be used while breastfeeding. A deficient infant needs separate assessment and treatment. Cyanokit is not withheld in a life-threatening emergency, but interruption of breastfeeding afterwards should be discussed because infant data are limited.
Hydroxocobalamin interactions
Hydroxocobalamin has few established medicine interactions. Tell clinicians about all medicines, supplements and herbal remedies.
Chloramphenicol
The blood-cell response to hydroxocobalamin may be reduced.
Oral contraceptives
Blood hydroxocobalamin concentrations may be lower, but treatment effectiveness is not expected to fall. Vomiting or severe diarrhoea can separately reduce pill protection.
Antimetabolites and many antibiotics
They may interfere with microbiological vitamin B12 assays, affecting interpretation rather than hydroxocobalamin’s action.
Common questions about Hydroxocobalamin
Answers are fully visible for fast scanning and source review.
How quickly does hydroxocobalamin start working?
It starts replacing vitamin B12 straight away, but symptom improvement may take days or weeks.
Can hydroxocobalamin be used for pernicious anaemia?
Yes. Cobalin-H and Neo-Cytamen are licensed for pernicious anaemia, in which vitamin B12 absorption is impaired.
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.