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Pernicious Anaemia Society
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Vit B12 issue please respond

I have vit b 12 injections every 3 month the Dr wants me to take the same orally dose 1.000 up daily in between! I am stable at present having had non Hodgkin's lymphoma. However in May I had a new air tic valve and two stents. I am permanently tired and haveb IVIG PREMARIN INFUSION EVERY 28 days.. Ou consider more oral vit b 12 appropriate and safe when I am still so lethargic? What are the side affects I'd with the three monthly injections could this be too much medication? Sorry I have lost confidence having been so I'll.. I look forward to your response. Thank you very much..

4 Replies

Hi vlfreer sorry to read that you are feeling so unwell.

Please make sure that you have a healthy level of Folate as this is essential to process the B12.

It is thought that one cannot overdose on B12 as any excess is excreted via the urine.

I am not a medically qualified person but there are others on here who will be able to give you good advice.

I wish you well


The tablets could help - You are having injections because your ability to absorb B12 in from your diet is impaired. 99% of B12 is absorbed in the ileum and if this mechanism is broken - that's why you need the injection, but that still leaves 1% being absorbed outside the ileum.

That means, that in theory you will be absorbing about 10mcg - which is about 4x RDA for B12 from each of the tablets. This wouldn't be enough to correct a deficiency but could be enough to keep your B12 levels where you need them to be after the injections and that could help you.

There certainly isn't a problem with toxicity from B12 - the treatment for cyanide poisoning is 5000x the amount you would be taking orally administered intravenously - and that is the treatment of choice because of the lack of toxicity.

You could talk through with your GP based on how your symptoms return after you have had a B12 shot - if you notice a difference from the shots and it lasts a while ... and you don't have neurological symptoms ... then it is worth giving it a try to see if it does help to keep your B12 levels where they need to be for you - but you need to monitor symptoms carefully.

If you have neurological symptoms then the treatment regime recommended by BCSH and NICE (assuming you are in UK) is 3xweek loading shots until symptoms stop improving (review at 3 weeks) followed by maintenance every 2 months ... though even that may not be enough.

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to reiterate

1000mcg a day orally isn't going to be harmful. It may do nothing or it could be helpful.

If you get on fine with the injections then the tablets should be no different.

Although there are no large scale studies of use of high dose oral there are many smaller scale studies that have shown it to be effective for some people - including one study that looked at effects over a longer period of time - ie 18 months mentioned in this review


Your post implies that your GP is proposing this as an addition rather than a replacement to your maintenance shots. If your GP is proposing this as an alternative to shots then that would be a different matter altogether. I personally would go with trying it but keeping a diary and monitoring symptoms and if it doesn't work then ask if for an alternative experiment with more frequent shots.

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I receive monthly B12 injections and take 1000 µg of B12 orally every day. At present, my B12 levels seem to be where the neurologist would like them to be. I was diagnosed with low B 12 in August and had loading doses, but since starting monthly injections, I have been supplementing with daily oral B12 as well. As mentioned above, I'm not sure it helps, but it doesn't seem to hurt and I have had no noticeable adverse effects .


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