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Pernicious Anaemia Society
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Post-injection exhaustion, symptoms

Hi there,

I was recently diagnosed with PA, and have had two injections (every 3 months) since my initial booster series of several injections.

With the booster series, I ended up feeling brilliant, energetic, the pins and needles went away, all was well. With the two injections since then, however, I have felt lethargic for about a week afterwards, and my energy levels haven't really improved. I also notice occasional slight chest pain, which I don't normally have (subsides after a few days). I'm noticing pins and needles again in my left foot, just a week after my last injection. A few things to note:

- I keep my B12 in the fridge - it is a dosage of 1mg Hydroxocobalamin every 3 months.

- I self-inject into shoulder muscle (I practised this with the nurse at my GP, and she said I was doing it right).

- I have a very busy lifestyle - I work in several different places over the course of the week, have commitments most evenings, cycle a lot, don't have a lot of downtime (however, I've arranged to do my injections on days when I can just crash afterwards).

Any thoughts / similar experiences?


4 Replies
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Hi Nataliak. Hello and welcome.

I agree with Hidden, you are being under treated for your B12 deficency: that is why your symtpoms are returning so soon after your three monthly injections and, incidentally, why you felt so much better when you were having the loading dose (more frequent) injections.

There has been a vital 'missed-step' in your treatment. People with B12 deficiency who have neurological symptoms need a much more intensive course of B12 injections in order for the nerves to repair properly.

Following the six loading doses given on alternative days, those with neurological symptoms should continue to have every other day injections until there is no further improvement. (For some people, this can take many months - up to two years). After this stage, injections are then given every eight weeks - though this is not enough for some people to remain symtpoms free and well - but that another story). Many GPs are not aware of this regime of treatment and fail to prescribe it when neurological symptoms are present.

I think it would be a good idea to revisit your GP, explain about your neurological symptoms and the fact that they return so soon after your three monthly injection, and ask to be put on the alternate-day regime of injections for those with neurological symptoms.

Your GP can find details of this treatment in a book called the BNF: there will be a copy on his/her desk. It's the second item down in the section for hydroxocobalamin so your GP will have to read further then they usually do. πŸ˜‰

At the end of this reply I'm going to insert some links to information about pernicious anaemia and12 deficiency. The links include information and guidelines about the treatment of B12 deficiency (especially the importance of treating with frequent injections when neurological symptoms are present), and also information about the common misconceptions that many GPs have about pernicious anaemia and B12 deficiency. Hopefully this information will help you approach your GP with a request for more frequent injections. It would be useful print the documents, identify anything that is a pertinent to your case, highlight the relevant sections and take the information along to share with your GP.

Also - people with PA (and the B12 deficiency it causes) often have other absorption problems which can result in other deficiencies - which can make you feel very unwell.

One of the most important is folate. B12 and folate work together so if you are deficient or have low levels of folate the body cannot utilise B12 properly. If your GP hasn't checked your folate levels it would be a good idea to ask for that to be done.

Iron deficiency anaemia is also common in people with PA. Has your GP checked your ferritin levels (one of the markers for iron deficiency anaemia). Again a good idea for this to be checked if it hasn't been already.

Low levels of vitamin D can also be a problem, so worth having this checked as well.

It's worth mentioning that GP's often say blood test results are normal when they're not. For people with B12 deficiency being at the lower end of the 'normal' reference range is often not good enough. Most people here ask for copies of their blood test results (you at legally entitled to these) so that they can check for themselves (unfortunately it's not unusual to find that abnormal results reported as normal). If you get any test results and you're not sure what they mean you can post them on the forum, together with the reference ranges, and people will be able to help with interpretation πŸ˜‰.

Finally, please do go back to your GP and ask for more frequent B12 injections, as per the British Committee for Standards in Haematology (BCSH) Cobalamin Deficiency Guidelines (included in the links below).

Please do post again if you have any more questions or problems getting your GP to treat you appropriately. Lots of lovely folks here to pop along and offer help and support.

Good luck… and here come the links (looks like a lot of reading but most of them are only one page long… and they're all very interesting πŸ˜€πŸ˜€.

b12researchgroup.wordpress.... (Serious Caution Note about the use of Oral and Sublingual B12 Supplements)

evidence.nhs.uk/formulary/b... (BNF B12 Deficiency: Hydroxocobalamin Treatment Regimes)

pernicious-anaemia-society.... (PAS Symptom Checklist)

stichtingb12tekort.nl/weten... (BSH B12 Deficiency / PA Diagnostic Flowchart)

onlinelibrary.wiley.com/doi... (British Committee for Standards in Haematology (BCSH) Guidelines: Treatment of B12 Deficiency and Folate Disorders)

bloodjournal.org/content/bl... (Haematologist B12 Treatment Review March 2017 – Includes Advice No Reason to Advise Against Self-Injection/More Frequent B12 Injections)

cks.nice.org.uk/anaemia-b12... (NICE Guidelines Treatment of B12 / Folate Deficiencies)

onlinelibrary.wiley.com/doi... (UKNEQAS B12 Treatment Alert, Neurological Symptoms and Risk of Subacute Combined Degeneration of the Spinal Cord – Immediate Treatment with B12 Injections)

stichtingb12tekort.nl/weten... (Problems with Serum B12 Test)

stichtingb12tekort.nl/weten... (Testing B12 During Treatment)

stichtingb12tekort.nl/weten... (Misconceptions About B12 Deficiency – Good to Know Before Seeing GP)

stichtingb12tekort.nl/weten... (B12 Treatment Safety / Long Term Treatment for neurological symptoms)

stichtingb12tekort.nl/weten... (B12 Deficiency: Neurological Symptoms Can Present Even When B12 is β€˜In-Range’ and Without Macrocytosis (large red blood cells) or confirmed PA Diagnosis)

stichtingb12tekort.nl/weten... (B12 Deficiency and Intrinsic Factor – Can Be Negative and Still Have PA)

stichtingb12tekort.nl/weten... (B12 Deficiency and Neuropsychiatric Symptoms)



Thanks so much for all the information and support. I'm going to try to see my GP on Tuesday, and it will no doubt be helpful to come armed with this information. :-) Last time my blood was checked, I requested a copy of the results, and everything was within the "normal" range, but this may have changed. I'm not surprised to hear, though, that neurological symptoms take a bit longer than the usual 6 top-up doses to deal with... Will post to update on the results! Thanks again. X

1 like

πŸ‘ good luck with your GP...look forward to the update πŸ˜€



I've assumed you're in UK.

Might be worth contacting PAS (Pernicious Anaemia Society) before appt.


PAS tel no +44 (0)1656 769 717 answerphone so messages can be left.

The PAS can sometimes intervene on behalf of PAS members by writing letters.


There are stories on Martyn hooper's blog about how PAS has helped people.


UK B12 treatment info

This next link gives info on regime for people with B12 deficiency neuro symptoms


If GP looks in their copy of BNF (British National Formulary) details of UK b12 treatment is in Chapter 9 Section 1.2

All UK GPs will have access to BNF, probably a copy sitting on desk or bookshelf. It's also possible to get own copy too.

UK b12 treatment info is also in "BSH Cobalamin and Folate guidelines", about a quarter through document.


My experience has led me to believe that not all UK GPs are aware of the BSH Cobalamin and Folate Guidelines. I gave my GPs a copy, plus a copy of Martyn Hooper's book

"What You Need to Know About Pernicious Anaemia and Vitamin B12 Deficiency"

Martyn Hooper is the chair of PAS (Pernicious Anaemia Society). I found another of his books useful "Living with pernicious anaemia and Vitamin b12 deficiency" becuase I could recognise aspects of my experience in the case studies.

Another B12 book

"Could it Be b12" by Sally Pacholok and JJ. Stuart (USA authors)

Very comprehensive book about B12 deficiency with lots of case studies

I am not a medic just someone who has spent years trying to find out what's wrong.


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