This is my first time posting I was diagnosed with Pernicious Anemia and B12 Deficiency in 2010, which up until January of this year I was having the injection every 12 weeks. My recent blood test for B12 showed I was overdosed so GP has now prescribed it at 6 monthly intervals .
I have never been given any advice or information other than you have been diagnosed and will need injections for the rest of my life. Does this mean I no longer have Pernicious Anemia or B12 Deficiency?
Thank-you for reading
Written by
Miler1969
To view profiles and participate in discussions please or .
No , you cannot overdose on vitamin B12. Your doctor is obviously very badly informed about Pernicious Anaemia, which is an autoimmune condition which cannot be cured , and needs B12 injections LIFE -LONG . . You have a formal diagnosis , so you must be treated . This means you need injections often enough to keep all symptoms at bay .
Once you have started B12 injections for Pernicious Anaemia , blood testing is not required . You will have PA for the rest of your life . But you will not suffer from B12 deficiency if you have your injections often enough to keep the symptoms of B12 deficiency at bay . Symptoms vary from patient to patient . The most common are exhaustion , breathlessness , palpitations , brain fog , anxiety , and “ pins and needles “ in hands and feet ( which can progress to numbness ) - there are many more symptoms.
You doctor needs to read the latest guidelines on B12 deficiency and Pernicious Anaemia which NICE ( National Institute for Health and Excellence) now calls Autoimmune Gastritis . These guidelines were published in March 2024.
Some PA patients seem to be able to manage on very high daily doses of B12 in tablet form , but many cannot . I for example need a weekly injection to keep well. Which means I have to self inject, as NHS will not prescribe that . Patients on this forum get their B12 ampoules from excellent German online pharmacies, ( no prescription needed for B12 ampoules in Germany .
Have you any return of symptoms ? If so , you must get your old regime of 3 monthly injections reinstated asap . ( if they were adequate, otherwise you need them more regularly)
Let us know how you get on . Just take care how you tell your doctor how ignorant he/ she is . Your doctor is totally at sea when it comes to Pernicious Anaemia . Your B12 level must be high and stay high . It’s the one vitamin that you cannot overdose on !
There are several books on Pernicious Anaemia written by the founder of PAS , Martyn Hooper ( Amazon )
I have just had another look on the result of my blood test for Serum Vitamin B12 level. It says it’s 1324ng/l (180-0 - 915.0). Above high reference limit so I’m assuming as it’s above 915 is the reason he has cut it back. I do worry about PA as years ago you died from it. I also suffer from Anxiety and only can describe it as brain fog. Any advice appreciated thanx
That range does not apply to Pernicious Anaemia patients . If he read the guidelines published by NICE , he would know that it’s a waste of time to test B12,when you are having injections . Your doctor is totally ignorant on Pernicious Anaemia. My B12 is right off the range -over 2000 . and has been for 10 years You must have more regular injections which he will not provide if you read the contributions on this forum you will see that we all self inject . Your anxiety is a symptom of B12 deficiency. I will send you information that you need to self inject. You cannot overdose on B-12 . Some patients need to inject daily . . Doctors don’t want to employ t nurses -the cost comes out of the sum paid to the surgery to run the practice . and will affect their salary . ( for goodness sake don’t mention this !) All of us on this forum are self injecting. I will send you the information that you need later today .
Must add that self injecting is easy and cheap ( about £2.00 everything included )
I urge you to do this .I know it sounds drastic but it is important . I was so very nervous at first , but it’s routine now . Because of delaying in jections , I have irreversible problems with my feet . Don’t want you to have that .
Please note that the PAS who sponsor this forum do not encourage self-injection with B12 without the support of a medical practitioner, though they do recognise that many patients feel forced to go down this route because they are unable to get more frequent treatment from their GPs. As a result the PAS allows this forum to share information on safe sources etc for patients who do feel that they need to self inject.
It is certainly not the case that everyone on this forum self-injects.
Miler, like you I was also given no information about B12 deficiency when I was diagnosed and wasn't even told at that point that injections would be for life. It is very difficult to find good quality information.
PA as used in this forum is an autoimmune disorder that attacks the mechanism by which we normally absorb B12 leading to deficiency. The symptoms associated with PA are the symptoms of the B12 deficiency this autoimmune disorder causes. These symptoms - which can include macrocytic anaemia (which gives the condition the anaemia part of its name) are treated by correcting the B12 deficiency. The most efficient way of doing this is injections, which replaces the liver as a store of B12 with the blood as a store of B12. This is one reason why testing of B12 levels once injections have started isn't recommended because it the serum B12 test results become meaningless. The normal range doesn't apply. After an injection your B12 levels will be really high and then they will gradually reduce over time, mainly as excess B12 is removed eg by the kidneys.
Many medical professionals are hopelessly confused by the condition because they will be aware that B12 is stored in large quantities in the liver and released as needed. They haven't realised that the mechanism for releasing these stores no longer works because it relies on the same mechanism used to absorb B12 from your diet, so they are still thinking that the liver is involved in storage so you should be okay.
Many medical practitioners are also unaware of how many processes that go on in your cells use B12 and think that B12 deficiency is just about anaemia - it is a lot more complicated than that, but this can lead to them noticing that the anaemia is cured and thinking that means everything is okay. It can also lead to them thinking that you can't be B12 deficient unless you have anaemia - though many of the symptoms are neurological in origin and can develop well in advance of anaemia.
To talk about overdosing on B12 is a non-sense. Hydroxocobalamin is used to treat cyanide poisoning. For this it is given intravenously in doses 5000 -10000 times the does you have received over half hour intervals. It is the preferred treatment because of its lack of toxicity. Also, after an injection your B12 levels will be off the measurable scale and then fall over time as mentioned above most of the B12 is generally lost in the first 48 hours because the rate of removal is higher when the amount in your blood is higher.
Levels in blood do not measure how effectively B12 is being transferred to and used in your cells. For some patients the effect of very high levels of B12 in serum seems to make the process that transfers the B12 to their cells less efficient meaning the B12 seems to stay in their blood longer but their symptoms don't reduce - or they come back when levels are really high - because not enough B12 is actually getting into the cells for all the processes that need it to work properly. Symptoms are a much better guide to frequency of treatment than blood tests.
Another possible treatment route for patients is high dose oral/nasal treatment which relies on a secondary absorption method - passive absorption. Although absorption in this way amounts on average to 1% of the dose taken there is considerable variation in how effective it is in individuals and for somewhere around 30-40% of people this method is much less efficient so this delivery method doesn't work for them. In the case of a severe B12 deficiency it would also be a slow way of reversing the deficiency and given that there seems to be a 6 month window on reversing nerve damage it can't be used as an alternative to injections in these cases.
Please note that some neurological symptoms seem to be down to the role B12 plays in facilitating neurotransmitters rather than damage caused by not having B12 to maintain the insulating layer around nerve cells - which is nerve damage that has the window for reversal.
PA as a cause of B12 deficiency has other consequences on the health of the gut which really need monitoring if PA is identified as the cause of deficiency - though the usual tests for PA don't currently include one that is really sensitive enough to rule out PA if it comes back negative - though there is a test involving gastrin which seems to fill this gap but is not yet available widely enough.
a) GPs tend to work of averages - but live human's don't work in that way and we are all different.
b) for some metabolites (eg insulin) normal ranges match with levels most people need for processes to function properly. This isn't really the case for B12 because individuals tend to maintain levels at a specific point in that range (use of the liver store), so even if a specific individual has a result in that range it doesn't guarantee that they are at the point that is right for them. Serum B12 is a difficult test to interpret anyway so symptoms are important. In diagnosing deficiency due to an absorption problems significant falls over time are probably more effective than single point test.
c) High B12 and symptoms of B12 deficiency can be an indicator of liver and kidney disorders. In these instances it is the liver and kidney disorders that are causing the high B12 levels rahter than the other way round but I suspect that medics are sometimes confused about the direction of causality which leads some to think that high B12 can cause the liver and kidney problems, giving rise to the notion of 'overdosing.
" My recent blood test for B12 showed I was overdosed so GP has now prescribed it at 6 monthly intervals ."
I am very concerned on your behalf that your GP is giving you injections only twice a year.
I'm not medically trained but I don't think it's possible to overdose on B12 as the excess would pass out of the body in urine.
The BNF (British National Formulary) suggests that patients with neurological symptoms should have maintenance injections every 2 months. For those without neurological symptoms, it suggests injections every 2 - 3 months.
Do you have or did you have neuro symptoms?
Some links I post may have details that could be upsetting to read so you may want to have a supportive person read through it with you.
I don't know why your GP tested your B12 levels.
PAS (Pernicious Anaemia Society) article - Testing B12 During Treatment.
Might be helpful to keep a daily or weekly symptoms diary. Maybe pick up to ten symptoms to track. Score severity daily or weekly. Note any new symptoms that appear. Note dates/amount of any treatment given. This could be useful evidence of deterioration or improvement of symptoms to show GP.
Link about writing letters about B12 deficiency to GP if unhappy with treatment.
Thankyou so much for taking the time to reply to my post.
I appreciate any information as I have never been given any other than what I have found through searching the internet and other sufferers.
I must admit I am worried about the GP only recommending the B12 injection every 6 months and I am gong to go back and get a second opinion especially as I have PA as well.
I am currently sat at our local urgent treatment centre for something else and mentioned to the GP there about having the injections dropped and he said are you sure you did not mishear what he said b cause as a GP I would never reduce them especially with PA.
These were published some years ago so some bits may need updating. I know UK guidance on treatment for B12 deficiency has changed since Martyn Hooper wrote his book but it still has lots of useful info.
"What You Need to Know About Pernicious Anaemia and B12 Deficiency" by Martyn Hooper
Martyn Hooper is the former chair of PAS (Pernicious Anaemia Society).
"Could it Be B12?: An Epidemic of Misdiagnoses" by Sally Pacholok and JJ. Stuart (US authors)
Very comprehensive with lots of case studies.
Sally Pacholok is a US campaigner on B12 deficiency issues. She has some online articles and videos about B12 deficiency.
PAS website has Personal Stories from PAS members.
They are always keen to hear other stories from PAS members.
If you join PAS maybe you could submit your story.
I haven't posted links to some of my detailed replies yet as didn't want to add to your anxiety.
Anxiety is a symptom of B12 deficiency. I can relate to at least some of what you are saying as I suffered both mental health problems and many neurological symptoms.
Mental health and neurological symptoms may get worse if your treatment is delayed/inadequate.
In my opinion, six months is a very long time to be without B12 injections for someone with B12 deficiency from PA.
Many UK forum members turn to treating themselves when NHS treatment is not enough for them. Some get B12 injections privately, some try high dose oral B12 (1000mcg or higher) but this doesn't work for everyone (didn't for me and many others on this forum).
There are moves across UK to put more people onto high dose oral B12 tablets as an alternative to B12 injections.
My personal opinion after reading many articles is that there is very little peer reviewed research with large samples of patients showing that high dose oral B12 tablets are as effective in managing symptoms of PA and B12 deficiency from other non dietary causes.
There are forum members who turn to self injection...I feel this is a last resort.
If you search online for "UK Survey self injection B12 deficiency" it will show a study where UK patients who self injected B12 were interviewed. Some of them were doing it because they couldn't get the treatment they needed.
Please think about joining PAS and calling their helpline.
At the very least, I hope they can point you to some useful info to pass to your GP.
Search for "Wolffenbuttel B12 deficiency" to find other articles he's written, including one for Mayo Clinic in US and one for BMJ (British Medical Journal).
His most recent article is an overview of treatment/diagnosis.
Search for "Wolffenbuttel B12 deficiency overview 2024" to find it.
In my personal opinion he's one of the few doctors who really understands B12 deficiency.
I posted recently about a Nature.com article, published 2025 about the NICE B12 deficiency guideline which might be a good one to pass to GP.
Search for "Nature 2024 NICE diagnosis management B12" to find it.
If your GP surgery is adamant that you can only have an injection every 6 months and your symptoms are returning/getting worse/new symptoms appearing then might be worth ringing NHS 111.
If you have increasing neuro symptoms eg tingling, pins and needles, numbness, gait issues (meaning a strange way of walking), balance problems etc especially if they start to affect spinal area then I really think that counts as an urgent medical issue.
Maybe you could also push to see a neurologist if you have neuro symptoms.
There is no guarantee that seeing a specialist means better treatment and better understanding of B12 deficiency.
Talking to local pharmacist might also be useful as they should have a good understanding of medicines/drugs including hydroxocobalamin.
If you were diagnosed with PA then you've got it for life.
If you were found to be B12 deficient for a different reason [that's not the same as PA] then that could be cured.
'PA' has been used misleadingly as shorthand for 'B12 deficiency anaemia' but it's certainly not the same thing. PA is an autoimmune condition, and the anaemia is a symptom of this. Some folks with 'PA' are not anaemic. However, without treatment, the outlook is 'pernicious' as in 'deadly, fatal', etc.
Measuring B12 levels when someone is getting injections is pointless, wasteful and misleading. It's akin to noticing through the window that it's raining outside, but then stepping out just to make sure it's wet.
If you are desperate, and needing a B12 injection , you can get them easily from beauty salons and where I live , some hairdressers . They are allowed to do this as long as the injections are offered for “ anti-ageing” purposes etc , and not offered for medical purposes . Crazy , isn’t it ? The cost is from about £30.00
Some B12 deficiency patients require B12 injections as frequently as daily. I am one. I recently tried injecting every other day and did poorly.
One of the best authors of medical journal articles on B12 diagnosis and treatment is Bruce Wolffenbuttel. This is a link to a recent one of them. To get it in a better format, scroll down and click the "PDF" tab.
Your doctor is out to lunch. They should not have tested your B12 when you are getting injections. You will have PA for the rest of your life. You are not going to overdose on it, even if you have injections of the amount you are getting several times per day. Some people on this forum need it that often. You are in danger of getting symptoms like fatigue and nerve damage if you are not getting injections often enough. Most people with PA need it more often than every 3 months. I get my husband to give me an injection once per week as I get symptoms back in 3 weeks. Best wishes!
Content on HealthUnlocked does not replace the relationship between you and doctors or other healthcare professionals nor the advice you receive from them.
Never delay seeking advice or dialling emergency services because of something that you have read on HealthUnlocked.
Possible Pernicious Anemia
Pernicious Anemia Information 
Pernicious anemia at twenty two!!!!!
Can anyone tell me how to manage pernicious anemia as my eyes are failing and my GP will not help.
Pernicious anemia, muscle spasms and aching bones
