Feeling worse after B12 shots - Pernicious Anaemi...

Pernicious Anaemia Society

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Feeling worse after B12 shots



I’ve started a series of weekly 1mg methyl B12 shots, and none of my symptoms have improved. I just had my 2nd shot this morning. I find I still have issues with stumbling, clumsiness, vision, pins + needles, dry mouth + eyes, tinnitus, muscle pain, and digestive issues. I notice that the tinnitus in particular has gotten worse. My energy has dropped as well, and some shortness of breath has returned. This particularly sucks because I had just started to feel better after about a year of garbage health.

Is this a sign that I shouldn’t be taking the shots, or that they’re somehow bad for me? If not, how long does it take for things to even out?

If anyone else has gone through this I’d love to hear from you. Thanks.

11 Replies
clivealiveForum Support

Hi ilyfunnybunny

It is not uncommon for some symptoms to appear to get worse before they get better as the B12 you are having starts repairing the damage done to your nervous system and your brain starts getting multiple messages from part of the body it had "forgotten about" or lost contact with.

I sometimes liken it to a badly tuned radio on which you have turned the volume up high trying to catch the programme you want when all of a sudden the signal comes in loud and clear and the blast nearly deafens you.

A lot will depend on the severity and longevity of your B12 deficiency as to how long before there is no further improvement or recovery.

Some symptoms will "disappear" quite quickly whereas others may take months or even years. There is no set timescale as we are all different.

It is also important that your Folate level is monitored as this is essential to process the B12.

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.


I am not a medically trained person but I've had Pernicious Anaemia (a form of B12 deficiency) for more than 46 years.

I wish you well.

Hi, thank you for reaching out. I do understand this, but what worries me is that none of my symptoms feel better, not just some. In fact, after my 2nd shot just about everything feels worse. So I'm concerned that I may have made a wrong move here, especially since none of my doctors would actually test for serum B12, despite my explicit request. I'm being given B12 therapy on the basis of high homocysteine.

I just had the same thing, and found this post helpful, too: healthunlocked.com/pasoc/po...

Thanks, that's reassuring. How long did it take for you to feel normal, or even better?

I have had my 5th shot only yesterday, the first 3 made me more miserable than I already was, but I now seem to be starting to feel slightly better. And normal...I hardly remember what normal is, so I am looking forward to that ;-)

Any reason why you’re having methylcobalamin? There’s a lot of rubbish on the interwebs about how this is more ‘natural’ but either hydroxocobalamin or cyanocobalamin is cheaper, more stable and is just as effective, if not more effective.

Some people also have a bad reaction to methylcobalamin.

I've been given methylcobalamin because it is the "active form,” I’m assuming because some people have lower capacity to utilize other kinds of B12, and giving methyl is a way of hedging your bets. The shots also include a B-complex. At this point its hard to tell whether I’m having a bad reaction to it, or this is just my life.

Yes, methylcobalamin is one of the two ‘active’ forms of B12. But that doesn’t mean it’s better than any other form.

When B12 enters the cell the first thing that happens is that the top ligand is removed to form cobal(II)amin. It doesn’t matter if you take hydroxocobalamin, methylcobalamin adenosylcobalamin or cyanocobalamin - they all end up exactly the same.

Elsewhere in the cell the cobal(II)amin binds to the enzyme methionine transferase. A molecule of methylfolate also binds to the enzyme and transfers it’s methyl group to the cobal(II)amin to form methylcobalamin. This then transfers that methyl group to homocysteine, forming methionine.

So if you take methylcobalamin it is broken apart in the cell. Even if it weren’t it wouldn’t be able to bind to the enzyme and, therefore, wouldn’t be able to do its job.

Honestly, this is what I want a doctor for. It's extremely difficult to truly understand body chemistry — none of these systems work in a vacuum, there's always some other substance or system that can determine their outcome — and I don't think I should have to become a biochemist in order to feel well. I've read about MTHFR mutations, and active forms, and micronutrient deficiencies, and I don't really understand it. I'm just desperate to feel well, so I'm jumping at almost anything with a positive anecdote behind it that seems to match my situation. And I'm not supposed to understand these things — my body is supposed to do all of this work naturally, without the involvement of my conscious mind or copious supplementation, and when it fails a physician who's dedicated their life and career to understanding the operations of the human body should be able to jump in to explain and assist. But, as many of us on the forums have found, such people don't really exist. So I understand why patients may turn to the gritty details of medical science — because we're really on our own.

Thank you for your information, but your chemical diagramming just reminds me of how many hours of research I've done over the past two years and how little it's affected the outcome of my health. Knowing how B12 is supposed to behave in the cell tells me very little about how the situation is actually unfolding in my own misbehaving body, and what I can do to make it stop.

Apologies if I use your post as an opportunity to vent a little. Really, thank you, and I appreciate you trying to help.

I fully understand your frustration as it mirrors mine.

I’ve spent a couple of years trying to understand how all of this works, and I start with a degree in chemistry and 33 years working as a biochemist. I know enough to rule out many of the myths but I still don’t know why I feel rough all the time and absolutely terrible if I don’t inject at least once a week.

It’s all convinced me that there’s more going on with B12 than is currently known. If I ever won 5 million on the lottery I’d try to investigate.

kngswim in reply to fbirder

Funny as just today I was thinking maybe I'll go back to school to study B12! I was wondering how there can still be so many unknowns about it & lack of education surrounding it!

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