B12 Injections don't feel like they work - Pernicious Anaemi...

Pernicious Anaemia Society
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B12 Injections don't feel like they work


I constantly feel exhausted even straight after having the b12 injections. I have been on 3 monthly injections now for around 2-3 years and have recently felt like the injections no longer do anything for me.

I spend most of my time when I'm not in work asleep because I feel constantly exhausted. I have an awful memory and get pins and needles around my shoulder blades and in my hands too.

I have spoken to many doctors who have done blood test and say that my levels come back normal and say they have no idea what's making me have these symptoms and there is nothing more they can do.

I'm only 27 and feel like I have no life as it revolves around work and sleeping.

Any suggestions?

14 Replies
clivealiveForum Support

Hi Saraha90

Was your Folate level checked?

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

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.

Sadly the "one size fits all" syndrome doesn't work for everyone and it may be you need more frequent B12 injections than the twelve weeks you are on now,

Your doctor should be treating your symptoms not just looking at the computer screen.

The British Society for Haematology guidelines say on the Diagnosis of B12 and Folate Deficiency "In the presence of discordance between the test result and strong clinical features of deficiency, treatment should not be delayed to avoid neurological impairment".


Make a list of your symptoms and present this to your doctor and ask him to treat you according to your symptoms and (perhaps) even re-start you on loading doses "until there is no further improvement" according to the N.I.C.E guidelines below. Click on the link, then on "Scenario: Management" and scroll down to "Treatment for B12 deficiency"


If possible take someone with you who can validate your neurological symptoms as the doctor is less likely to pooh pooh you in front of a witness.

I am not saying that this is an easy thing to do but try to stay calm, write out what you want to say and keep to the script and be confident that you are "in the right" and your facts are correct.

Have you any idea why you became B12 deficient in the first place?

I am not a medically trained person but I've had P.A. (a form of B12 deficiency) for more than 45 years.

I wish you well

in reply to clivealive

The blood tests they did apparently checked all my levels and I was told they were all as they should be. They didn't go through the levels individually with me. I just get told that everything is fine with the results and nothing more they can do. It's like they know that tiredness is part of b12 deficiency so they just brush it off.

I have been taking some vitamins as well which contain folate, iron and b12 as my iron levels were low and thought it wouldnt do any harm to top up folate and b12 as well but doesn't seem to make a difference, like everything else I have tried. I get made to feel like I'm complaining over nothing and that I'm wasting time as they just try get rid of me each time.

I don't think even increasing my injections would do anything as I still come home after the injection and fall asleep.

Again I didn't get told why the b12 decency happened I had 2 different blood tests done. After the first one they asked if I was a vegetarian/vegan as they said my B12 had come back low as well as my iron level. I've never been vegetarian as I like my food too much so they did another blood test then got told I was going to be put on b12 injections for the rest of my life.

clivealiveForum Support
in reply to Saraha90

You are entitled to have copies of your blood tests. They may charge a few pennies.

If you post them here I'm sure there are people more knowledgeable than I who will be able to translate them..

Anyone at any age, can become B12 deficient. However, certain people are at an elevated risk. They include the following:

Vegetarians, vegans and people eating macrobiotic diets.

People aged sixty and over

People who’ve undergone any gastric and/or intestinal surgery, including bariatric surgery for weight loss purposes (Gastric bypass).

People who regularly use proton-pump- inhibitors. H2 blockers, antacids, Metformin, and related diabetes drugs, or other medications that can interfere with B12 absorption.

People who undergo surgeries or dental procedures involving nitrous oxide, or who use the drug recreationally.

People with a history of eating disorders (anorexia or bulimia).

People with a history of alcoholism.

People with a family history of pernicious anaemia.

People diagnosed with anaemia (including iron deficiency anaemia, sickle cell anaemia and thalassaemia).

People with Crohn’s disease, irritable bowel syndrome, gluten enteropathy (celiac disease), or any other disease that cause malabsorption of nutrients.

People with autoimmune disorders (especially thyroid disorders such as Hashimoto’s thyroiditis and Grave’s disease) Type 1 diabetes, vitiligo, lupus, Addison’s disease, ulcerative colitis, infertility, acquired agammaglobulinemia, or a family history of these disorders.

Can you "see yourself" among any of the above people?

Does an "Intrinsic Factor Antibodies" test sound familiar?


Unfortunately GPs and even many medical specialists tend not to understand a lot about how B12 works - especially how it works after loading doses.

Do you notice any improvement after the loading doses - even if it is very short lived?

On average people who are being treated with B12 shots report that they need to keep their levels above the top of the normal range to feel well - for some of us that means keeping our levels off the top of the measurable range. This is probably because the initial loading shots raise B12 serum levels and in some people that kicks of a reaction that tries to trap the B12 in your blood and doesn't allow it to pass through into your cells. If you have really high levels then enough trickles through but as the levels drop less and less trickles through until eventually very little or none gets through leaving you deficient at the cell level. This effect is common enough for it to be recognised that all the symptoms of B12 deficiency with high serum B12 levels can be a symptom of conditions - liver and kidney problems - that can lead to levels of B12 in serum rising


It may be worth asking the doctors if they could check homocysteine and MMA levels - which may show that you have a functional B12 deficiency if they come back high. Treatment with more frequent B12 shots is an effective way of treating this. However, it may be very difficult to get your GP to recognise this unless they are willing to do reading around the subject.

There are options around treating yourself - I actually find that frequent use of a nasal spray worked for me. Sublinguals/high dose oral also works for other people ... and it is possible to source injectable B12 from outside the UK and inject yourself. B12 isn't toxic.

"The blood tests they did apparently checked all my levels and I was told they were all as they should be."

As others have said get print outs of your blood results and post them here. Some GP's idea of 'Normal' is odd, very odd.

Thank you for everyone's advice! I will try and get a copy of my blood test results. I'm sure the last lot of blood tests were done straight after I had the B12 injection because they realised I was due a blood test after they had already given the injection. Surely this would show my levels higher than they usually are?

clivealiveForum Support
in reply to Saraha90

It was pointless testing so soon after a B12 injection unless it comes back LOW - it will probably be sky high.


"The blood tests they did apparently checked all my levels and I was told they were all as they should be"

Bitter experience taught me to always get copies of all my blood test results after being told everything was fine/normal and then finding abnormal and borderline results on copies.

Access to Medical Records (England)



Are you in UK? I'm asking because patterns of b12 treatment vary from country to country.

Do you have any neurological symptoms eg tingling, pins and needles, tinnitus, tremors, memory problems, balance issues?




b12d.org/admin/healthcheck/... (may need to be B12d.org member)

In UK, people who are symptomatic for B12 deficiency with neuro symptoms are supposed to get the following pattern of treatment...

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

"I have been on 3 monthly injections now for around 2-3 years"

You appear to be on the standard UK B12 treatment which is

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

If you're in UK, I'd suggest reading all the following documents/articles

BSH Cobalamin and Folate Guidelines


Flowchart from BSH Cobalamin and Folate Guidelines


BMJ B12 article






B12 websites

PAS website


PAS tel no +44 (0)1656 769717 answerphone

B12 deficiency Info website


UK B12 blogs

Martyn Hooper's blog


B12 Deficiency Info blog


B12 books I found useful

"What You Need to Know About Pernicious Anaemia and B12 Deficiency" by Martyn Hooper

Martyn Hooper is the chair of PAS (Pernicious Anaemia Society). Book is up to date with UK b12 guidelines.

"Living with Pernicious Anaemia and Vitamin B12 Deficiency" by Martyn Hooper

Has several case studies.

"Could it Be B12?: An Epidemic of Misdiagnoses" by Sally Pacholok and JJ. Stuart (USA authors)

Very comprehensive with lots of case studies.

I am not medically trained.

Yes I'm in the UK and I do get pins and needles feeling and have rubbish memory too. I had injections every other day for 2 weeks and then been on 3 monthly injections.


Have you asked your GP why you are not on Neurological treatment regime?

GP can find details in BNF Chapter 9 Section 1.2 (See BNF link in above post) and also in BSH Cobalamin and Folate Guidelines (link in above post).

Is GP aware of potential neuro consequences if b12 deficiency is under treated?


PAS article on SACD, (sub acute combined degeneration of the spinal cord) available to PAS members.

pernicious-anaemia-society.... See page 2

Link about writing letters to GP about B12 deficiency.

Point 1 is about under treatment of b12 deficiency with neuro symptoms.


Have you seen a haematologist?

NICE CKS link in above post suggests that GPs should contact haematologist if patient with b12 deficiency has neuro symptoms.

"I do get pins and needles feeling and have rubbish memory too"

Have you seen a neurologist?

There can be many possible causes of neuro symptoms so may be worth excluding other possible causes.

It's your right to ask for referrals although GP does not have to agree to referrals.

PAS (Pernicious Anaemia Society)

Do you have a PA diagnosis or do you suspect PA is a possibility? If yes, may be worth joining and talking to PAS.


Your case is common and many people need more B12 and supporting supplements than we are given.

I managed to get another course of loading doses and found I was better again but the positive effects soon wore off again so I followed the examples of many others and started to self inject every day and take a broad spectrum multivitamin and mineral supplement plus extra folate, potassium, magnesium and iron.

I am now mostly well and my neurological symptoms that you describe are OK.

Good luck with getting the treatment you need.

My mum has B12 injections and didn't think they were working after moving to a new GP. She now has them done in a community clinic and feels much better. She suspects the nurse at the GP's surgery wasn't injecting into the muscle as it wasn't painful. It could also be that it's a different brand of B12. Her blood tests came back ok too.

I hope you get to the bottom of it and feel better soon.

Some people do not have the correct biochemistry to utilise B12 - possibly due to a SNP such as MTHFR. So "decent" levels of B12 are useless if your body can't metabolise same. Ask your doctor if he/she is administering a Methyl-B12 injection. The "methyl" form of the vitamin is pricier but more "bio-available".

I haven’t read every post here but agree with what I have read. I too have non specific B12 deficiency. I get injections every 2 months but presume that my liver and kidneys regulate active B12 to what was previously the right level for my needs. That paradigm changes when you become deficient. Injections by themselves just restores liver stores and may not give you sufficient active B12 in the blood. I take a daily supplement of 2000 microgrammes as oral sublingual every morning before eating and definitely before drinking tea, whilst taking a multivitamin and mineral. So far this has worked so might be worth a try. This is not a temporary solution, in my experience but likely to be life long, as the injections will be.

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