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Pernicious Anaemia Society
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Sublingual b12 versus b12 injections?


Came across this article/website (use the read only functions) saying you don’t need injections and benefits of methylcobalmon vs CYANOCOBALAMIN

(Apparently in uk they use methylcolbalamin only- think this is a USA site)

I’m aware the site is selling the vitamins too but what do people think? I’ve seen sublingual b12 vitamins mentioned on here.

Also says injections online are usually CYANOCOBALAMIN because they are cheaper...

Any thoughts?

9 Replies

It hydroxocobalamin that is most often given as injections in the UK. Cyanocobalamin is the form most common in the US. Methylcobalamin is a form that is touted as superior although there isn't proof that it is any better than the other forms. Trying the different types is really the only way to figure out if one version works better for you personally than another version.

Injections definitely work. Sublinguals work for some people but not for others. The same is true for the skin patches. It's really up to you to decide what things you are willing to try out to see how well they work for you.


a) NHS in the UK uses Hydroxocobalamin

b) hydroxocobalamin has two potential advantages over cyanocobalamin

i) can be used by those rare individuals who have lebers syndrome

ii) on average it is retained 2x as long as cyanocobalamin - but there is a lot of variation from individual and it certainly isn't true that everyone retains hydroxocobalamin longer than cyanocobalamin.

c) whilst it is true that high dose oral can be very effective and may be preferable for some individuals, it is not a particularly efficient way of getting B12 into someone who has an absorption problem. It relies upon using passive absorption - outside the gut - which averages at around 1% in patients with PA - some will have more and others will have less - so it means using really high doses very regualrly.

d) although most B12 from a shot is lost in the first 24-48 hours - filtered out by the kidneys and passing out of the body in urine - it still remains the most efficient way of raising B12 levels quickly - important if someone is experiencing neurological problems.

e) there is an awful lot of hype out there over methylcobalamin - claims that it is more natural - which are based on flawed logic

i) B12 is bound to various proteins as it goes through the body - the form that actually passes into a cell is not the same as the molecule that is ingested in the gut or injected into the blood

ii) all B12 used in medicine is manufactured

iii) there are 2 forms of B12 used by different processes in the body - methylcobalamin and adenosylcobalamin. There aren't any reported cases of people who can't convert both cyano and hydroxo to both types (though they the process may not run as efficiently), but there are reported cases of people who cannot convert methyl to adenosyl.

f) there appears to be at least one genetic variant that doesn't respond well to methylcobalamin - with the result that the process that recycles neuro-transmitters goes into hyperdrive.

g) getting B12 into your blood isn't quite the same as getting it in to your cells - sometimes raising B12 levels in bloods results in a reaction that actually shuts down the process that allows the B12 to pass into cells - though keeping levels in blood really high does seem to result in enough getting through - possible that starting with high level oral rather than with injections might avoid this reaction but there haven't been any studies to look into functional B12 deficiency, how to treat it, identifying when it is likely to be an issue, and what might be the best way of treating an absorption problem when there is a likelihood of functional B12 deficiency.

Basically treating B12 deficiency is a long way from being a one size fits all condition. As such I would be very wary of any sight claiming that one type of B12 or one method of delivery is much better than any other. It is the experience of the individual that actually matters.

Personally I use a mixture of injections, sublinguals and nasal sprays and use all 4 types of B12 as they help me with different symptoms.

In terms of absorption: oral is on average 1%, sublinguals slightly better - but only just over 1%, nasal averages about 3%, injection will be 100% ... but that is only about the amount that gets into you - one small part of the process of getting it to your cells and using it in the cells.


Thanks everyone- that’s cleared up a lot of issues for me. So much info can be overwhelming to read online sometimes.

Much less confused now ☺️👌🏻

1 like

I live in the U'K and was started on cyanocobamalin B12 injections in 1972 as it was the only type available at the time.

It was either that or eating raw liver three times a day.

When Hydroxocobamalin was introduced in the mid 1980s I had an allergic reaction to it and so have continued with the cyano ever since and I'm still "clivealive" and over 75 :)

Are you monitoring your Folate level?

I wish you well.


Lol clivealive and kicking 😊

I’ve been taking folic acid on and off for a year as we’re trying to conceive. Interestingly enough I read that folic acid Tx can mask an Underlying b12 deficiency- and I don’t know if it’s coincidence but for two weeks I’ve run out of folic acid and my symptoms seem so much worse! I thought it was psychosomatic until I read that.


It is important that your Folate level is monitored as this is essential to process the B12.

There is a complex interaction between folic acid, vitamin B12 and iron. A deficiency of one may be "masked" by excess of another so the three must always be in balance.

Symptoms of a folate deficiency can include:

symptoms related to anaemia

reduced sense of taste


numbness and tingling in the feet and hands

muscle weakness


Folic acid works closely with vitamin B12 in making red blood cells and helps iron function properly in the body

I am not a medically trained person and I wish you well and goodnight.

1 like

Thanks- sorry I meant to say I had folate and iron tested too which were in range, but I’ve had supplementation generally for those so not surprising. B12 was only one out of range. Some of others were in low end.

Thank you again for your advice.

Happy holidays


The latest BMJ research indicates that neurological symptoms should be treated with injections every other day until no further improvement to avoid permanent damage:

This is part of a letter from Dr Wilhelmina Rietsema in 'Rapid responses' to the BMJ research document that explains the different forms of B12:


" There are two active forms of the B12 enzyme in the human cell. First, Methylcobalamin acts as a co-enzyme for the conversion of homocysteine to methionine. Methionine then acts as a methyl-donor to a great number of reactions that need a methyl group, including the synthesis of myelin, serotonin, dopamine, noradrenalin, DNA and phospholipids.

Second, Adenosylcobalamin is a co-enzyme for the conversion of L-methylmalonyl-CoA into succinyl-CoA which feeds into the citric acid cycle.

"Is it important which form is used in treatment? In most people, it does not matter. They can convert cyano- and hydroxo-cobalamin into the active forms needed. However, I have recently reported a case in which it did matter. The severe vitamin B12 deficiency, including dementia and psychosis, responded to treatment with high dose oral methylcobalamin, but not to equally high dose oral hydroxocobalamin. [1]

1. Rietsema WJ. Unexpected Recovery of Moderate Cognitive Impairment on Treatment with Oral Methylcobalamin. Journal of the American Geriatrics Society 2014;62(8):1611-12 doi: 10.1111/jgs.12966[published Online First: Epub Date]|. "

PS Sally Pacholok ("Could it be B12 deficiency?"), recommends supplementing injections with B12 supplements.


It’s Hydroxocobalamin not cyannacobalamin in uk.

Hydroxocobalamin is very good injection form.

I’ve read if you take high dose B12 (5000) sublingual in oral form it still works even if you have absorption problems...may take much longer to work as injections are quick to work.

Cyannacobalamin injections may still work but as Hydroxocobalamin is used in uk and is tried and tested and works great you don’t need to go out of your way to purchase cyannacobalamin.

Hydroxocobalamin is also most stable form of B12....that is what I use.

Very good.


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