How frequently do you get B12 injecti... - Pernicious Anaemi...

Pernicious Anaemia Society

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How frequently do you get B12 injections?


Hi everyone, I've been reading around on here and it got me wondering how often people get their B12 injections? Some folks seem to get them quite frequently. At the moment I am scheduled to have one every 3 months. Does that sound like often enough? Is there individual differences in how much B12 we use up?

I got a blood test in September and my levels were over 2000 (so high I believe that they couldn't read it), but that was not long after an injection. A recent blood test showed levels were 455, and I got my injection after bloods were taken. Is this a normal decrease rate? Roughly every 3 months should do me without having to keep checking levels?

Apologies for the million questions, I don't want to get low again and have to deal with all that comes with it.

10 Replies

Most people try and get the frequency of injections to keep their symptoms away.

This varies from person to person and the sort of b12.

Depends on what your symptoms are.

Neurological symptoms need a different regime. There are many links posted on here that you can find. Bnf guidelines es .

In th Ik it's now 2-3 monthly. After loading doses.

Gp s can prescribe more. As its supposed to be on symptoms.

Once on injections 12 blood tests are not necessary. In fact seem to cause more problems with getting g the right frequency.

I personally seem to need more. I'm not symptom free as healing times vary too. Its getting g the best you can get .

There is no point at all in testing levels if injecting, unless you want to wait six months. That's why the British Committee on Standards in Haematology recommend it not be done.

The correct frequency of injection is that needed to keep symptoms at bay. For some people that is every three months, for others it's every day. The only way to tell is to try.

If you feel that three months isn't enough ask your doc to switch to every two months. The guidelines changes a year ago, but the doc probably doesn't know that (there are dozens of changes each month and it's hard to keep up with them all).


"At the moment I am scheduled to have one every 3 months. Does that sound like often enough?"

If you're in UK, both patterns of recommended treatment allow for B12 injections every 2 months, it's possible your GP does not realise this.

1) UK recommended treatment pattern for B12 deficiency without neuro symptoms is ...

6 B12 loading jabs over 2 weeks followed by a jab every 2 or 3 months

2) UK recommended treatment pattern for B12 deficiency WITH neuro symptoms is ...

A B12 loading jab every other day for as long as symptoms continue to get better then a jab every 2 months

You appear to have been put on the first pattern if you are getting jabs every 3 months.

Do you have any neurological symptoms eg

tingling, numbness, pins and needles, burning sensations, insect crawling sensation, tinnitus, muscle twitches, muscle fasciculations, flickering eyelids, restless legs syndrome RLS, vertigo, clumsiness, migraine, dropping things, bumping into things, strange gait (unusual way of walking), word finding problems, balance issues, brainfog, proprioception problems (problems with awareness of body in space) etc?

Does your GP have a list of all your symptoms, especially any neurological ones?

Symptoms of B12 Deficiency


In relation to B12 deficiency, GPs often look for signs of peripheral neuropathy PN especially signs of sensory neuropathy so worth mentioning signs of PN.

Link about PN

Link about writing letter to GP if under treated for B12 deficiency with neuro symptoms

I feel it is more effective to put queries about treatment in a brief as possible, polite letter to GP. Letters to GPs in UK are ,as far as I know , supposed to be filed with medical notes so harder for GP to ignore them.

Letters could contain symptoms list, test results, relevant personal and family medical history, extracts from UK B12 documents, any other supportive evidence.

Worth mentioning that GP can find treatment info in their BNF book Chapter 9 Section 1.2

although possible that some GPs may be using an out of date BNF book.

You could draw your GPs attention to consequences of under treatment if you have neuro symptoms.

Neurological Consequences of B12 Deficiency

PAS news item


PAS article about SACD, sub acute combined degeneration of the spinal cord, access to PAS members only.

pernicious-anaemia-society.... See Page 2 of articles.

Blog post from Martyn Hooper's blog, mentions SACD


If neuro symptoms present, have you been referred to

1) a neurologist?

If you see a neurologist, ask them to check your proprioception sense. Two tests that help to do this are Romberg test and walking heel to toe with eyes closed. Problems with proprioception are associated with B12 deficiency. Vital that these tests are only done by a doctor due to risk of loss of balance. If no tests are done with patient's eyes closed then unlikely that proprioception has been fully tested.

2) a haematologist?

NICE CKS link (down page)recommends that GPs seek advice from a haematologist for patients with b12 deficiency with neuro symptoms. If GP won't refer you, they could at least contact a local haematologist by letter and ask for advice.

Don't expect better treatment from a specialist although I obviously hope you get a specialist who knows about B12 deficiency; ignorance about B12 deficiency exists among specialists as well as GPs.

UK B12 documents

BSH Cobalamin and Folate Guidelines

Flowchart from BSH Cobalamin and Folate Guidelines

Flowchart outlines process for diagnosing PA and Antibody Negative PA in UK

BMJ B12 article

Emphasises need to treat patients who are symptomatic even if their B12 level is within range.


BNF guidance on treating b12 deficiency changed recently.


BNF Children


Unhappy with Treatment (UK info)?

Letters to GPs about B12 deficiency

CAB NHS Complaints

HDA patient care trust

UK charity that offers free second opinions on medical diagnoses and medical treatment.

Some forum members need far more B12 than the NHS guidelines allow for, so many resort to self treatment.

There is more B12 info in long replies I wrote on another forum thread. See link below.

I am not medically trained.

P.A. /B12 deficiency patients need differing numbers of B12 injections to keep symptoms at bay.It’s not understood exactly why .Maybe to do with the length of time it’s taken to be diagnosed. Which is difficult to know . More research needed . Someone on this forum described it as if we had a dam inside us , and only when that dam was full , did B12 overflow into our cells . Not a scientific answer , but it’s a useful analogy ! And that varies enormously from person to person.

This is not acknowledged by the medical authorities . That’s why when the B12 readings are high , doctors will often stop the injections , even though guide lines state that B12 testing is not required once injections have started .

You get to know how often you need an injection by injecting before you know that the symptoms will return . The hard and fast ruling of every 3 -2 months serves patients badly . I need an injection every week , so have had to resort to self - injections .Disapproved of strongly by my GP ( toxic he said - perhaps confusing it with B6- I don’t know .) But after 4 years of weekly injections , the horrible symptoms of P.A. have disappeared ,and I’m only left with burning feet ( instead of completely numb ones )

Take Methylcobalamin ('active' B12) which bypasses the enzymatic processes required to activate the synthetic form, and may, therefore, produce more significant results than the cheap B12 supplements. Additionally, genetic differences have been identified regarding the activity of these enzymes with some individuals unable to process and utilize non-active forms of B vitamins.

They work out cheaper too in fact, as you need much less of them.

Other 'activated' B-vitamins available are Riboflavin 5'-Phosphate ('active' B2 or Riboflavin), Pyridoxal 5'-Phosphate ('active' B6 or Pyridoxine) and L-5-MTHF (L-5-Methyltetrahydrofolate, 'active' Folic acid), another commonly deficient B-vitamin.

It may also be that some side effects, like numbness of the extremities (caused by excessive B6 supplementation as Pyridoxine Hydrochloride), could be avoided with the active forms. In fact, excessive B6 is most likely an actual deficiency as the body cannot make use of the excess due to poor enzyme activity. Just look at the typical symptoms of B6 deficiency - with numbness of the extremities being top of the list!

Similar thing with Folic Acid. It can worsen allergies in susceptible individuals. But early studies have shown that L-5-MTHF ('active' Folic acid) may help avoid the issue.

Has to be better than monthly injections? Which, no doubt, Big Pharma has a Monopoly on!

Certainly no harm in trying them.

helvella in reply to MaskedNinja

You wrote:

Take Methylcobalamin ('active' B12) which bypasses the enzymatic processes required to activate the synthetic form, and may, therefore, produce more significant results than the cheap B12 supplements.

I am surely not alone in finding it confusing to see reference to Methylcobalamin as "active B12" when that name has already been widely accepted for holotranscobalamin? (As in Active B12 blood tests.)

All purchaseable B12 supplements are synthetic. Yes, you can get B12 from some foods, but it is simply not available in quantity for manufacturers to make B12 supplements from foods rather than microbes.

What is wrong with hydroxocobalamin as a supplement?

MaskedNinja in reply to helvella

I don't know, you tell me.

I actually copy and pasted that from here:


Admittedly no references to be seen. I'll look for some.

MaskedNinja in reply to helvella

Then this research suggests that oral supplementation of B12 (no specific form) can be as effective as injections, at least as maintenance:


Oral vitamin B12 replacement at 1000 μg daily is an adequate alternative to IM B12 injections. Close monitoring with clinical review and repeat vitamin B12 levels are required on a monthly basis to review symptoms and ensure normalization of B12 deficiency. Elevated serum Hcy and MMA levels should be included in future assessments of pernicious anaemia and corrected with normal levels in patients with pernicious anaemia."

Better than nothing.

helvella in reply to MaskedNinja

There are people here who would strongly disagree with some of the things said.

I've had Pernicious anemia for years. I started having the injections every 12 weeks but as I'm getting older I struggle to wait that long so I now have mine every 10 weeks.

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