Pernicious Anaemia Society
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B12 Injections - Loading Dose - Advice Please

Apologies for the length of this post but I just want to make sure I cover everythng!

I've finally bitten the bullet. The ampoules arrived yesterday so I dutifully trotted off to my local needle exchange and obtained the necessarily paraphernalia and came home, shaking like a leaf and feeling a bit like a junkie if the truth be told.

I prepared everything (I would give an account of the mistakes I made and make you laugh but this post is long enough already!) I braced myself, the needle hovered for about three hours (well that's how long it felt anyway!) and I eventually did the deed.

It was such a relief to discover the pain in my right leg disappearing and the numbness in my left leg starting to recede. I actually walked up my stairs normally within 10 minutes of having the injection.

By the evening the bits that had un-numbered had started to throb a little (a bit like when a dental anaesthetic wears off) and I was so relieved I nearly cried. I slept for nine good hours last night without any pain waking me up in the middle of the night and woke up feeling refreshed for a change.

My plan was to follow what I've read and do an injection every other day until everything is back to normal but by late morning, the throbbing in my right leg was back and I'm now a bit worried.

My original B12 level was 376 back in the middle of August and I started supplementing with 1000ug MethylCB every day on 25 August which helped with the brain fog and mental clarity really quickly. On 11 September I added oral spray MethylCB which cleared my bursitis within a couple of days and everything progressed for a little while. I changed the oral MethylCB to Jarrow sublingual on 9 October as I'd developed a throbbing pain which felt like it was in the bones of my right leg and keeping that company was a side order of pins and needles in my left thigh, both of which would wake me up at 3am and have a party. My thought was that I wasn't absorbing the tablets properly (I had been on PPIs for 25 year but not taken them for 18 months).

My last blood test on 19 Oct showed B12 at 1476 (I asked the lab about discontinuing supplements and they advised I'd need to discontinue for 3-4 weeks before the test - not really a palatable an option for me). By this point the patch on my left thigh was permanently numb and I'd experienced a "ripping" sensation as well as cascades of pins and needles around the area which seemed to be spreading so I was quite surprised by the test result which was when I ordered the injections. I haven't yet had the Active B12, homocysteine or MMA tests (funds are a little limited by thyroid tests and other supplements and timing). I am due to see my GP again on Monday but am not hopeful that he'll take any notice as he wouldn't accept the results of my own Blue Horizon tests and wants to refer me to a neurologist if the results of B12 test he wanted to do come out normal (which they will)

My worry is that every time I change/increase treatment or dosage, everything is fine for a while - it's like I take three steps forward and then one backwards. I know something like this takes time to heal and I may be worrying unnecessarily (in which case please feel free to deliver a slap) but if anyone has any advice or insights, I'd be more than happy to read them.

6 Replies

Please don't worry! It's early days yet. Just keep on injectingand remember to get 1)folate 2) Potassium Very important. I have after 1 1/2 years of injecting--reached my optimum result I think. Numbness gone, just burning left. Everyone is different.and has different experiences. You are now on the right road I'm sure. and I wish you all the best! Someone else will give you a better answer than mine. Best of luck 1


Wedgewood, Are you suggesting Folate and Potassium testing, or supplements? Probably testing, but just want to warn folks about taking potassium on their own without physician's monitoring...very risky in many ways, but especially to heart function.

Best, Leilani

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I am really suggesting that peope plenty of folate in its NATURAL FORM Green leafy vegs peas etc, and the same for potassium -Bananas etc. I'm sure it's best to tale vitamins in their natural form where possible


However, tetrahydrofolic acid (the NATURAL form) isn't as good as synthetic folis acid. One needs half the amount -

"If chemically pure folic acid (pteroyl monoglutamate) is used to provide part of the RNI, by way of fortification or supplementation, the total dietary folate, which contains conjugated forms (pteroyl polyglutamates), could be reduced by an appropriate amount. On average the conjugated folate in natural foods is considered to be only half as available as synthetic folic acid. For example, the recommendation of usual mixed forms of folate in the diet is 400 µg/day, but 100 µg of this given as pure folic acid would be considered to be equivalent to 200 µg of dietary mixed folate. Hence, only an additional 200 µg of dietary folate would be needed.

The FAO/WHO expert group agreed with the findings of the Food and Nutrition Board of the US National Academy of Sciences (22):

Since folic acid taken with food is 85 percent bio-available but food folate is only about 50 percent bio-available, folic acid taken with food is 85/50 (i.e., 1.7) times more available. Thus, if a mixture of synthetic folic acid plus food folate has been fed, dietary folate equivalents (DFEs) are calculated as follows to determine the EAR:

µg of DFE provided = [µg of food folate + (1.7 x µg of synthetic folic acid)]

To be comparable to food folate, only half as much folic acid is needed if taken on an empty stomach, i.e., 1 µg of DFE = 1 µg of food folate = 0.5 µg of folic acid taken on an empty stomach = 0.6 µg of folic acid with meals (22)."


Once you start supplementing with B12, serum blood tests for B12 levels are pointless. Your serum level can be high, but you can have B12 deficiency at cellular level. Having an active B12 test is also pointless once you start supplementing. I started self-injecting about 3 weeks ago and have gradually increased them to almost daily. If I try any less than this, symptoms return. We are all different and I think the best thing to do is to go by how you feel and inject accordingly. You can't harm yourself as B12 is non-toxic even in high doses. All the best!

1 like

Thanks LadyNZ. I wasn't sure whether the Active B12 would be pointless as well once I was supplementing. I guess then I'll just have to go on symptoms, which is what I've been doing up until now and hope that it won't take too long before the pain and pins and needles recede (although I am trying to be realistic about it). I just really hate having to do all this by myself because my GP is an arse. Thank goodness for everyone on here - I'd probably have gone completely mad otherwise.


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