Hydroxocobalamin
What it is
A natural, non-synthetic form of vitamin B12 found in foods, with a half-life 3–5× longer than cyanocobalamin and superior tissue retention due to tighter protein binding. Standard for injectable B12 in the UK, EU, Canada, and most countries outside the USA because it sustains blood levels longer with less frequent dosing. Unlike cyanocobalamin, it scavenges cyanide ions (the approved clinical antidote to cyanide poisoning) and binds excess nitric oxide. Oral absorption is limited without intrinsic factor — sublingual, injectable, or intranasal routes achieve far higher bioavailability for those with deficiency or absorption issues.
Dose
Oral/sublingual: 500–1,000 mcg/day for deficiency correction. Maintenance: 250–500 mcg/day. Injection: 1,000 mcg IM (prescription only).
Time of day & tips
For B12 deficiency with neurological symptoms, sublingual or injectable routes are far superior to swallowed tablets. Sublingual hydroxocobalamin bypasses poor intrinsic factor absorption. Urine may turn pink/red — completely harmless. Consider sublingual or nasal spray if consistently low B12 despite oral supplementation.
Cycling
Safe for continuous long-term use indefinitely — no B12 toxicity has ever been established. Monitor blood levels when actively treating deficiency to confirm correction.
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