What can be done if you react to B12 ... - Pernicious Anaemi...

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What can be done if you react to B12 injections?


I was diagnosed with B12 deficiency 2 years ago - my level was 154 ng/L. I was started on a loading dose. After 2 injections my ankles started to swell and the nurse decided to stop the injections. My B12 deficiency was just left and forgotten. My level went up to 395 just after the injections but has been falling ever since. It is now 201 and I am feeling very unwell. I have had peripheral neuropathy for over 5 months and over the last 2 days am experiencing numbness in my face. My GP has refused B12 injections and is referring me to a Haematologist and a Neurologist which is likely to take months. What can be done for people who react to the injection? I have tried sublingual tablets which I purchased myself but they made no difference to my symptoms. I would appreciate any help. Thank you.

8 Replies
clivealiveForum Support

Hi Catleighcat were the injections Hydroxocobamalin?

Do you know the cause of your B12 deficiency?

I'm not a medically trained person but there are others on here who will be able to advise you.

Hi. I dont know why I was/am B12 deficient. The GP never bothered to investigate. All I was told was that the injections were B12. Sorry to sound so vague but thats all I know :(

clivealiveForum Support
in reply to Catleighcat

I think now would be a good time for you to try and find out a bit more about why you are feeling as you do.

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, or infections such as h-pylori 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.

Women with a history of infertility or multiple miscarriages.

I know it's a long list but can you "see yourself" among any of the above people?

Symptoms of B12 deficiency tend to develop slowly and may not be recognised immediately. As the condition worsens, common symptoms include:

Weakness and fatigue

Light-headedness and dizziness

Palpitations and rapid heartbeat

Shortness of breath

A sore tongue that has a red, beefy appearance

Nausea or poor appetite

Weight loss


Yellowish tinge to the skin and eyes

If low levels of B12 remain for a long time, the condition also can lead to irreversible damage to nerve cells, which can cause the following symptoms:

Numbness and tingling in the hands and feet

Difficulty walking

Muscle weakness


Memory loss




Let me know how you get on with the above

I was already diagnosed B12 deficient in 2016. They stopped the injections due to ankle swelling and did nothing further to help me. Im trying to find out what doctors need to do if swelling occurs - there must be something as B12 deficiency cant just be left. I need to know as I feel my GP will use the previous swelling as an excuse not to give me B12 injections again.

clivealiveForum Support
in reply to Catleighcat

I've just looked up side effects of hydroxocobamalin and it would appear from what I have highlighted below your doctor may have been right to withhold further injections if they were hydroxo.

"If possible before you receive hydroxocobalamin, tell your caregivers if you have:

high blood pressure;

heart disease;

congestive heart failure;

liver disease;

kidney disease (or if you are on dialysis); or

if you have ever had a severe allergic reaction to hydroxocobalamin, Vitamin B12, or cyanocobalamin (Nascobal, Cobolin, Cyomin, and others).

Get emergency medical help if you have any of these signs of an allergic reaction: hives; chest tightness, difficulty breathing; swelling of your face, lips, tongue, or throat.

You may develop an acne-like skin rash within 1 to 4 weeks after you are treated with hydroxocobalamin. This rash should go away without treatment. Call your doctor if you have a rash that lasts longer than 4 weeks.

Call your doctor at once if you have a serious side effect such as:

bright red blood in your stools;

chest pain, fast or uneven heart rate;

severe shortness of breath, wheezing, gasping for breath, cough with foamy mucus;

swelling in your feet or ankles;

a light-headed feeling, like you might pass out; or

dangerously high blood pressure (severe headache, blurred vision, buzzing in your ears, anxiety, confusion, chest pain, shortness of breath, uneven heartbeats, seizure).

Common side effects may include:



acne, skin rash or redness;

red coloring of your urine (may last 2 to 5 weeks); or

pain, swelling, or irritation of your skin where the injection was given.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects."

I think you need to go back to your doctor and talk over your future treatment according to your present symptoms.

Please remember I'm not a medically trained person but I suggest you make a list of your symptoms to give to him also mentioning any of the "people" you can identify with in the list above.

I've already been through all this with my GP last Friday. Even if a person reacts to the B12 injection, they cant just leave and ignore a B12 deficiency surely? This is what I am trying to get to the bottom of.

clivealiveForum Support
in reply to Catleighcat

A lot will depend on the cause of your deficiency,

For example if it is dietary - eat more meat, fish, seafood. poultry, dairy produce etc., or check what medications you take that may affect absorption of B12 such as Metformin (for diabetes) or antacids etc.

Many on here self inject with Methylcobamalin that can only be bought from abroad. Should you decide to do that I suggest you post a new question on sourcing B12 and needles to get that information.

Personally I use a methylcobamalin "Boost" spray between my scheduled injections which can be bought over the counter at health stores or online.

You could ask help from the Pernicious Anaemia Society. It costs £29.00 for a year's membership.

To join the Pernicious Anaemia Society click on the link below and scroll down


I wish you well


Hi Catleighcat. You're right...you're GP cannot simply not treat your B12 Deficiency but must try to find a way to get B12 into your body. This is especially important as you are now experiencing neurolgical symtpoms.

It's possible that you may be allergic to some of the additives (excipients) in the b12, rather than the B12 itself, so perhaps your GP could try a different brand (checking for different additives first).

Some people who react to Hydroxocobalamin can tolerate cyanacobalamin (a different form of B12)...perhaps your GP could try you with this. Suggest this as a first step, since if you can tolerate cyanocobalamin it's then easy to continue B12 therapy.

Methylcobalamin is another option....though this is not licensed for use in the UK, injectable methylcobalamin can be purchased from some foreign pharmacies (though it's not always easy to source and does tend to be more expensive than either of the two other forms).

Some people who are allergic to B12 have to have injections done in hospital where an injection of antihistamines (and sometimes steroids for those badly effected) can be given at the same time to lessen any allergic reaction. This may sound extreme but those who are B12 deficient must receive treatment in order to prevent potentially irreversible neurolgical damage.

Also - the Pernicious Anaemia Society have identified two consultants in London who can offer advice about desensitising those who are allergic to B12, so that they can safely receive B12 injections.

If you are a member of the PAS, I suggest you telephone the helpline and discuss this with Martyn Hooper. He will be able to offer advice, give you information about the two specialists in London, or can discuss this with your GP, on your behalf, in order to progress this quickly. Or your GP would be most welcome to telephone Martyn for advice about this, perhaps the quickest route if your GP is willing - and they should be (no membership needed for this).

Here's a link to the PAS website where you'll find contact details:


It's quite shocking that your GP thinks it's acceptable to simply stop your injections...and then do nothing.

The most important thing is to first get (and continue) treatment for your B12 Deficiency...and then perhaps your GP can try to determine why you have it (we can advise further about that, if required).

Good luck with getting help with this. Please let us know how you get on and post again if you need further help.


P.s here are the diagnostic and treatment guidelines your GP should be following:

onlinelibrary.wiley.com/doi... (British Committee for Standards in Haematology (BCSH) Guidelines for the Disgnosis and Treatment of Cobalamin and Folate Disorders)

Suggest you share/discuss these with them since they seem to be unaware of the neurolgical (and other) havoc that untreated B12 Deficiency can wreak on the body.

Another p.s. worth nothing that because you have neurolgical symtpoms, you should be on an int save regime of B12 injections. 6 x loading doses over two weeks and the injections every other day, until no further improvement.

Here's the BNF guidelines for treatment (what your GP should follow - second or third paragraph down - many don't read that far:


Note: guidelines refer to Hydroxocobalamin but also relevant to other forms of B12. They also refer to treatment for pernicious anaemia and your GP May Day 'but you don't have pernicious anaemia' (you may well have, but that’s another story). The point here is that the treatment for pernicious anaemia is treatment for the B12 Deficiency it causes. So the treatment for B12 Deficiency is the same, whatever the cause (and there are many).


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