Pernicious Anaemia Society
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B12 too low in between injection cycles

I have been getting the B12 injection for over two years now, in the last year I feel I need the injection more often than every three months, after two months I start to get cracks at the corners of my mouth and feel very tired. My GP has said no, she can only give it on three monthly cycles as there is nothing probing if u get it more frequently there is no benefit. She also has refused to give me a blood test at this time as she says this cost a lot of money for blood tests when it's not going to be a true result as I have the injections😕 Can anybody offer advice on this or suggest an extra supplement that is available in UK, I have found in America u can get a b12 jelly type chew as a booster to use with the injection.

5 Replies

I need a B12 top up every 2 months and I need more than 1 but my doctor has agreed every 2 months otherwise my body starts to attack itself. Change doctor if she/he cannot work with your symptoms or get them to refer you to an autoimmune specialist.

Hope this helps?!


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Like Daphne says, try to change to a doctor who isn't an idiot.

Otherwise you can try self-injection, as many of us here do. There's plenty of good advice on this forum.

Otherwise there are several other alternatives....

If your deficiency is not caused by absorption problems (PA, H. pylori, GI surgery) then you can try high-dose (1000 - 5000 ug) tablets.

If you do have absorption problems then you need something that gets absorbed by another route. Sublingual (under the tongue) lozenges or sprays, intranasal sprays or skin patches all have their fans. Pick one and see how you get on.

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I've assumed you're in the UK.

"My GP has said no, she can only give it on three monthly cycles"

She can if you have neurological symptoms.

Do you have any neurological symptoms? See links below.


Symptoms Checklist in here. Other useful documents/articles as well.

Rest of website has lots of useful info. Person who runs it is a B12 deficiency sufferer.

The reason I'm asking is that the treatment for patients with B12 defic and neuro symptoms is more intensive than you are receiving. The info the GP needs is in the BNF (British National Formulary) Chapter 9 Section 1.2 The BNF is copyrighted so can't reproduce info here but this link contains similar info. Scroll down to Management section.

I have rung the PAS on more than one occasion. If you leave a message they will get back to you.


01656 769467

Do you know why you are B12 deficient?

Have you ever had an IFA test (Intrinsic factor Antibodytest) This can help to diagnose PA (Pernicious Anaemia) but is not totally reliable. Some people with PA get negative results.

In 2014 a new set of Guidelines came out. The "BCSH Cobalamin and Folate Guidelines" . Cobalamin is the scientific name for B12.

I was told in my area that the NHS should be following these new guidelines. Some GPs are unaware of these ne w guidelines. I read the whole document and printed out a copy of it for my GP who was unaware of it. The PAS library section on website has a summary of these guidelines. The BCSH Cobalamin Guidelines contain info on treatment and diagnosis which I hope to discuss with my GP.

Do you have recent results for ferritin, folate and fbc (Full blood count) tests. My understanding of what I have read is that a person needs good levels of iron and folate to have good uptake of B12. There can be useful clues on the FBC as to whether you have enough B12. High MCV and high MCH can indicate the possibility of macrocytosis and one cause of macrocytosis is lack of B12.

I learnt through bitter experience to get copies of all my blood tests as sometimes what I was told over the phone was not always what was on the copy.

Are you on any other medication? Some drugs can interfere with B12 uptake. Some are listed below but there are others that interfere that are not in that list.

Have you had any surgery involving nitrous oxide (also used in gas and air for labour pain relief)?

I am not a medic, just a patients who has struggled to get a diagnosis and wants people to have useful information.

Other useful links

My GP was interested in this article.

Martyn Hooper is the chair of the PAS. He has written several books about PA and B12 deficiency.


"Could It Be B12" by Sally Pacholok and JJ. Stuart

Very comprehensive book about B12 deficiency

"What You Should Know About Pernicious Anaemia and Vitamin B12 Deficiency" by Martyn Hooper


Does sound like your GP hasn't really tried looking for evidence one way or the other so easy to conclude that there isn't any evidence that more frequent injections would help.

The NICE guidelines, if I remember correctly, recommend referral to a haematologist if symptoms continue after treatment ... but then you'd be taking pot-luck with finding a haematologist who knew anything about B12.

In reality I don't think anyone has actually come up with a cogent argument for thinking that 3 months really is long enough for most people - just assume it is. In Germany the regime is monthly (also hydroxo). When hydroxo was introduced the regime was 1 month in the UK - it moved to 2 months in the 1960s after some research showed that on average people retained hydroxo twice as long as cyano - but the paper also showed a wide variation that you couldn't say everyone would retain it twice as long. Then in the 1980s it moved to 3 months ... and nobody seems to be able to trot out the support for that.

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I had the same problem, but went with my husband to support me, to ask for a trial of extra injections. My GP agreed, and I went back at the end of the trial period to explain how much better I felt. She has agreed to continue on six weekly injections. I had even offered to pay for the extra injections, but she said no need. I took a list of continuing symptoms to the first visit, and a list of those that had improved after the trial. You can but ask. Good luck. MariLiz

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