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Moderate evidenceVitamins & minerals

Hydroxocobalamin

The B12 form used for injections in much of Europe, because it stays in the body longer than cyanocobalamin. As an oral supplement it corrects deficiency like any other form, with no proven edge.

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What the science says

  • Corrects vitamin B12 deficiency Moderate evidence

    A Cochrane review of 3 randomized trials (153 people) found that oral B12 around 1000 µg/day normalised serum B12 concentrations as well as intramuscular injection — the route hydroxocobalamin is normally given by — at lower cost. The evidence was rated low quality due to small trial size.

  • No superiority over the other B12 forms Moderate evidence

    A review of cobalamin metabolism found no basis for ranking hydroxocobalamin above cyanocobalamin for prevention or treatment of deficiency; its advantage is pharmacokinetic (slower clearance after injection), which matters for injection intervals rather than for daily tablets.

Dosage & safety

Studied doseOral supplements typically supply 1000 µg/day. Medical injections are usually 1000 µg on a schedule set by a doctor. The cyanide-antidote use (5 g intravenously in smoke inhalation) is a hospital emergency treatment with no relation to supplements.
SafetyWell tolerated; high doses can tint urine pink or red. As with any B12, treating symptoms without establishing the cause of a deficiency can delay diagnosis. Hydroxocobalamin is preferred over cyanocobalamin in people with Leber's hereditary optic neuropathy and in renal impairment, where the cyanide moiety is a theoretical concern.

How to take it

TimingTiming does not matter.
With food?With or without food.
Worth knowingIt can tint urine pink or red for a day, which is harmless but alarming if nobody warned you.

Interactions

With medications

  • metformin

    Long-term metformin lowers B12 absorption. have B12 checked periodically

  • proton-pump inhibitors and H2 blockers

    Reduced stomach acid impairs B12 release from food. have B12 checked if you take them long term

With other supplements

  • high-dose folic acid or folate

    Folate can correct B12-deficiency anemia while nerve damage continues. check B12 status before taking high-dose folate

Well-established interactions only — this is not a complete list. Always tell your doctor and pharmacist what you take.

Frequently asked questions

Is hydroxocobalamin better than cyanocobalamin?

Not as a daily tablet: a review found no basis for ranking hydroxocobalamin above cyanocobalamin for preventing or treating deficiency, a moderate-grade conclusion. Its advantage is slower clearance after injection, which matters for injection intervals.

Can oral hydroxocobalamin work as well as B12 injections?

A Cochrane review of 3 trials found oral B12 around 1000 mcg/day normalised blood B12 as well as injections, at lower cost. The trials were small, so the evidence was rated low quality.

Why does hydroxocobalamin turn urine red?

High doses of hydroxocobalamin can tint urine pink or red for a day, which is harmless. It is otherwise well tolerated.

Who should take hydroxocobalamin instead of cyanocobalamin?

Hydroxocobalamin is preferred over cyanocobalamin in people with Leber's hereditary optic neuropathy and in kidney impairment, where cyanide in the cyano form is a theoretical concern. Oral supplements typically supply 1000 mcg/day.

Scientific references

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